Minggu3 biomechanics telkom university
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Transcript of Minggu3 biomechanics telkom university
BIOMECHANICS
1
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
DEFINITION
Biomechanics uses the laws of physics and engineering mechanics as well as biological and physiological principles to describe the motions of various body segments (kinematics) and understand the effects of forces and moment (kinetics) acting on the body
Occupational Biomechanics is a sub-discipline within the general field of biomechanics that studies the physical interaction of workers with their tools machines and materials to enhance worker performance while minimizing the risk of musculoskeletal injury
WHYbull Prevent problems that can cause injury to workers ie
Musculoskeletal Disorders (MSDs)
bull Improvement of (manual) working conditions
bull Improving organizational performance (efficiency
quality worker satisfaction)
bull EASNEP
COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE
1 less production output
2 increased lost time
3 higher medical costs
4 increased absenteeism
5 higher material costs
6 low-quality work
7 injuries sprains strains
8 increased probability of accidents and errors
9 increased labor turnover
10 less spare capacity to deal with emergencies
Source Total Cost ($) Notes
In-plant medicalvisits and treatments
14050 $50 per visit
Employee absences 127905 Each 1-week absencerequired 1 replacement worker
Work restrictions 16192 12 of the work restrictions required replacement workers
Job changes initiated by employee
13984 Each job change required retraining for 2 workers
Total Biaya 172131
Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)
CASE SHOULDER DISORDERS
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DEFINITION
Biomechanics uses the laws of physics and engineering mechanics as well as biological and physiological principles to describe the motions of various body segments (kinematics) and understand the effects of forces and moment (kinetics) acting on the body
Occupational Biomechanics is a sub-discipline within the general field of biomechanics that studies the physical interaction of workers with their tools machines and materials to enhance worker performance while minimizing the risk of musculoskeletal injury
WHYbull Prevent problems that can cause injury to workers ie
Musculoskeletal Disorders (MSDs)
bull Improvement of (manual) working conditions
bull Improving organizational performance (efficiency
quality worker satisfaction)
bull EASNEP
COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE
1 less production output
2 increased lost time
3 higher medical costs
4 increased absenteeism
5 higher material costs
6 low-quality work
7 injuries sprains strains
8 increased probability of accidents and errors
9 increased labor turnover
10 less spare capacity to deal with emergencies
Source Total Cost ($) Notes
In-plant medicalvisits and treatments
14050 $50 per visit
Employee absences 127905 Each 1-week absencerequired 1 replacement worker
Work restrictions 16192 12 of the work restrictions required replacement workers
Job changes initiated by employee
13984 Each job change required retraining for 2 workers
Total Biaya 172131
Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)
CASE SHOULDER DISORDERS
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
WHYbull Prevent problems that can cause injury to workers ie
Musculoskeletal Disorders (MSDs)
bull Improvement of (manual) working conditions
bull Improving organizational performance (efficiency
quality worker satisfaction)
bull EASNEP
COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE
1 less production output
2 increased lost time
3 higher medical costs
4 increased absenteeism
5 higher material costs
6 low-quality work
7 injuries sprains strains
8 increased probability of accidents and errors
9 increased labor turnover
10 less spare capacity to deal with emergencies
Source Total Cost ($) Notes
In-plant medicalvisits and treatments
14050 $50 per visit
Employee absences 127905 Each 1-week absencerequired 1 replacement worker
Work restrictions 16192 12 of the work restrictions required replacement workers
Job changes initiated by employee
13984 Each job change required retraining for 2 workers
Total Biaya 172131
Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)
CASE SHOULDER DISORDERS
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
COSTS OF IGNORING ERGONOMICS IN THE WORKPLACE
1 less production output
2 increased lost time
3 higher medical costs
4 increased absenteeism
5 higher material costs
6 low-quality work
7 injuries sprains strains
8 increased probability of accidents and errors
9 increased labor turnover
10 less spare capacity to deal with emergencies
Source Total Cost ($) Notes
In-plant medicalvisits and treatments
14050 $50 per visit
Employee absences 127905 Each 1-week absencerequired 1 replacement worker
Work restrictions 16192 12 of the work restrictions required replacement workers
Job changes initiated by employee
13984 Each job change required retraining for 2 workers
Total Biaya 172131
Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)
CASE SHOULDER DISORDERS
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
Source Total Cost ($) Notes
In-plant medicalvisits and treatments
14050 $50 per visit
Employee absences 127905 Each 1-week absencerequired 1 replacement worker
Work restrictions 16192 12 of the work restrictions required replacement workers
Job changes initiated by employee
13984 Each job change required retraining for 2 workers
Total Biaya 172131
Tabel 1 Total Biaya dari 93 kasus dari sebuah pabrik perakitan mobil(Punnett L et al (2000) Scand J Work Environ Health)
CASE SHOULDER DISORDERS
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
HUMAN SYSTEMS
bull In order to create EASNEP we need to know human limitation capability and function
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
HUMAN SYSTEM
sometimes overlapping set of subsystems people can use their fingers to read Braille (as sensors) and type (as effectors)
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MUSCULOSKELETAL
1 Tulang (Bones)
2 Jaringan penghubung (Connective Tissue)
3 Sendi (Joints)
4 Otot (Muscle)
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
1 BONES YOU NEED TO KNOW
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
EXTREMITIESAnalyses normally focus on the extremities (peoplersquos arms wrists hands legs and feet) and the lower back (spinal)
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
2 JARINGAN PENGHUBUNG (CONNECTIVE TISSUE)
Ligaments
ndash connect bones to bones
ndash eg lateral collateral in knee
Tendons
ndash connect muscles to bones
- eg rotator cuff multiple tendons within
carpal tunnel
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CONNECTIVE TISSUE AND BONES FUNCTIONS
1 Force transmission and movement
2 Posture support
3 Metabolism (blood cell manufacture)
4 Protection
5 StorageBuffer (calcium and phosphorus)
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
JOINTSbull Interface between two bones
bull Provides motion and pulleys for tendons
bull Synovial Joint
bull most common typebull no tissue synovial fluid forms
interfacebull Examples wrist elbow knee
shoulder
bull Cartilaginous
bull some motion but high load bearingbull Example spine
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MUSCLE Muscle Functions
ndash skeletal motion
ndash skeletal stability
ndash force production
Muscle mass (untrained) = 30-50 of total body mass
Muscle Composition
ndash 75 water
ndash 20 proteins
ndash 5 other (carbohydrates fats enzymes salts hellip)
Type Control
Smooth Autonomic (involuntary) NS
Skeletal Somatic (voluntary) NS
Cardiac Autonomic NS
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MUSCLE CONTRACTION
1048708 Muscle contraction is fundamentally caused by the bindingunbinding of two protein molecules actin and myosin
1048708 Membrane depolarization causes release of Ca2+
1048708 Ca2+ reacts with protein on actin molecule to expose binding sites
1048708 Myosin binds to actin and ratchets up (sliding)
1048708 Each event yields ~50-100Aring displacement
1048708 Energy required for unbinding
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
BIOMECHANICS ANALYSIS (1)
Analisis
sum Moment = 0
(LR) -(Fr)-(Wr2) = 0
F = (LR)- (Wr2) r
sum Gaya = 0
J+W = F + LJ
Wr2 J= F + L - W
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
BIOMECHANICS ANALYSIS (2)
Analisis
sum Moment = 0
Fr = (L(R+r))+(Wr2)
F = (L(R+r))+(Wr2)) r
sum Gaya = 0
J = F ndash L - W
J
W
r2
(Fr)-(L(R+r))+(Wr2)=0
Wr2
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
SIGN CONVENTIONS FOR CALCULATIONS
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
LATIHAN
Suatu benda kerja seberat 2 kg diangkat dengan satu lengan berat lengan tersebut 25 N Di ketahui jarak pusat beban lengan terhadap pusat beban benda sejauh 30 cm r = 5 cm R = 13 cm
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum)
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
JAWAB
a) Gaya kerja Otot Triceps
sum Moment = 0(F(005))-(25013)-((210)03)=0F=((25013)+((210)03))005F=(325+6)005F=185 N
b)Beban pada tumpuan sendi siku
sum Force= 0F-J-W- (P10) = 0J = F-W-(P10)J = 185 ndash 25 ndash 20 J = 140 N
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
LATIHAN
J
W = 25N13cm
5cm 28cm
= 400 N
Hitung a) Kekuatan otot yang diperlukan utk
mengangkat bebanb) Gaya yang diterima oleh sendi siku
(fulcrum) c) Berapa massa beban jika diketahui
keuntungan mekanis menggunakan katrol adalah 1
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
A SUCCESS STORYhellipAbbott had developed a new product the A-drug delivery pump The A-drug pump was very similar to the X-drug delivery pump a product that had been manufactured for the last several years but requiring manually intensive tasks including product lifting and transfer awkward posturing close visual inspection and repetitive motions
Compensation costs (2000)
Reaching pump from top of the cart $800
Lifting pump from line $57000
Repetitive lifting of pump $55000
Repetitive assembly work $10000
Abbott spent an additional $20000 on ergonomic improvements including portable lifting tables product handling turntables single shelf product carts conveyor systems foot rests ergonomic chairs automated presses tool fixturing and grip enhancements Implemented in 2002 there have been no OSHA recordables
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
BIOMECHANICS
MANUAL MATERIALS HANDLING
25
Yusuf Nugroho Doyo Yekti (YFN)
doyoyektiyahoocom
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
LESSON OVERVIEWWhat is MMH
MMH Activities
MMH Effect on Health
Recommended Weight Limit (RWL)
Case 1 Effect of Frequency Factor on RWL
Case 2 Effect of Horizontal Distance on RWL
Case 3 Effect of Vertical Distance on RWL
26
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
WHAT IS MANUAL MATERIALS HANDLING
Manual Materials Handling (MMH)
bull important application of ergonomic principlesbull particularly addresses back injury preventionbull that almost every worker performs MMH tasks
bull Either one-time (infrequent) dutybull or as part of regular work
MMH involves five types of activities
1 LiftingLowering
2 PushingPulling
3 Twisting
4 Carrying
5 Holding
27
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH ACTIVITIESLiftingLowering
bull Lifting to raise from a lower to a higher levelbull Range of a lift from the ground to as high as you can reach your
handsbull Lowering is the opposite activity of lifting
PushingPulling
bull Pushing to press against an object with force in order to move the object
bull The opposite is to pull
Twisting
bull (MMH Defn) act of moving upper body to one side or the other while the lower body remains in a relatively fixed position
bull Twisting can take place while the entire body is in a state of motion
28
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH ACTIVITIES (CONT)
Carrying
bull Having an object in onersquos grasp or attached while in the act of moving
bull Weight of object becomes a part of the total weight of the person doing the work
Holding
bull Having an object in onersquos grasp while in a static body position
29
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH EFFECT ON HEALTHMMH most common cause of occupational fatigue and low back pain
About frac34 workers whose job includes MMH suffer pain due to back injury at some time
Such back injuries account for 13 of all lost work + 40 of all congcompensation costs
More important than financial cost human suffering
rArrprevention of back injuriescrucial challenging problem for occupational health and safety
30
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Most common causes of back injuries
bull Tasks involving MMH gt workers physical capacitybull Poor workplace layout
Weight of the load lifted
bull For most workers lifting loads over 20 kilograms increased rArrnumber and severity of back injuries
Range of the lift
bull Preferred range for lifting isbetween knee and waist height
bull Lifting abovebelow this range is more hazardous
Location of load in relation to the body
bull Load lifted far from the body more stress on the back than the rArrsame load lifted close to the body
31
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Size and shape of load
bull Bulky object is harder to lift than a compact one of the same weight because it (or its centre of gravity) cannot be brought close to the body
bull Lifting a bulky object also forces a worker into an awkward and potentially unbalanced position
Number and frequency of lifts performed
bull How often the worker performs MMH tasks and for how long are extremely important factors
bull Frequently repeated long-lasting tasks most tiring the most rArrlikely to cause back injury
bull Highly repetitive MMH tasks also make the worker bored and less alert safety hazardrArr
32
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MMH EFFECT ON HEALTH (CONT)Work factors causing back injury during MMH
Excessive bending and twisting
bull Poor layout of the workplace risk for injury uarrrArrbull eg shelving that is too deep too high or too low unnecessary rArr
bending or stretchingbull eg lack of space to move freely increases the need for twisting rArr
and bendingbull eg unsuitable dimensions of benches tables and other furniture
force worker to perform MMH tasks in awkward positionsrArr add stress to the musculoskeletal systemrArr
bull eg work areas overcrowded with people or equipment stressful rArrbody movements
33
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
ESTABLISHING IF A LIFT IS TOO HEAVYNIOSH National Institute for Occupational Safety and Health (United States)
following recommendations are based on Revised NIOSH equation for the design and evaluation of manual lifting tasksrdquo
NIOSH lifting equation takes into account weight other variables in lifting tasks that contribute to the risk of injury
34
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
ESTABLISHING IF A LIFT IS TOO HEAVY (CONT)eg situation requires frequent lifts or lifting loads far away from the body
bull rArr there is an increased risk of injurybull Under these conditions reduce weight limit
bull from a baseline weight or load constant (LC)bull to a recommended weight limit (RWL)
A load constant (LC)
bull 23 kg (about 51 lb)bull established by NIOSH load that under ideal conditions is safe for
bull 75 of femalesbull 90 of males
The recommended weight limit (RWL)
bull Calculated using the NIOSH lifting equation
35
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CALCULATING THE RWLSTEP 1 measureassess variables related to the lifting task
Six variables considered in determining RWL
1 horizontal distance (H) the load is lifted ie = distance of hands from midpoint between ankles
2 starting height of the hands from the ground (vertical location V)
3 vertical distance of lifting (D)
4 frequency of lifting or time between lifts (F)
5 angle of the load in relation to the body (A)(eg straight in front of you = 0ordm or off to side)
6 quality of grasp or handhold based on the type of handles available (hand-to-load coupling C)
36
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CALCULATING THE RWL (CONT)Each of these variables assigned a numerical value (multiplier factor) from look-up charts
STEP 2 Calculate RWL using NIOSH equation(includes six multiplier factors)
RWL = LC x HM x VM x DM x FM x AM x CM
bull where LC is the load constant other factors arebull HM the Horizontal Multiplier factorbull VM the Vertical Multiplier factorbull DM the Distance Multiplier factorbull FM the Frequency Multiplier factorbull AM the Asymmetric Multiplierldquo factorbull CM the Coupling Multiplier factor
37
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CALCULATING THE RWL (CONT)
38
(AM)
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CALCULATING THE RWL (CONT)STEP 3 analyze RWL
If all multiplier factors are all in best range weight limit for lifting rArror lowering 23 kg (51 pounds)
If multiplier factors are not in best ranges weight limit must be rArrreduced accordingly
39
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DETERMINING THE MULTIPLIER VALUEFigure out the horizontal multiplierrdquo (HM)
bull Measure the distance the object is from the body measure (in cm) the distance from in-between the persons ankles to their hands when holding the object
bull Write down this numberbull Look up the number on the horizontal distance chart and find the
matching multiplier factorrdquobull Use this factor in the lifting equation
Repeat this process for the other 5 factors
40
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DETERMINING THE MULTIPLIER VALUE (CONT)Vertical Multiplier (VM)
bull Thisrsquos vertical distance of the hands from the ground at the start of the lift
bull Measure this distance (cm)bull Determine corresponding VM value on the chart
Distance Multiplier
bull Thisrsquos distance (cm) load travels updown from the starting positionbull Measure this distancebull Determine corresponding VM value on the chart
41
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DETERMINING THE MULTIPLIER VALUE (CONT)Frequency Multiplier (FM)
bull Thisrsquos how often lift is repeated in a time periodbull Determine
bull if the lift is done while standing or stooping for more or less than one hour (in total time for the shift)
bull how much time there is for rest between lifts
Asymmetric Multiplier (AM)
bull This measures if body must twist or turn during liftbull Measurement is done in degrees (360 being one complete circle)
42
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DETERMINING THE MULTIPLIER VALUE (CONT)Coupling Multiplier (CM)
bull This finds ldquocouplingrdquo ie type of grasp person has on the containerbull It rates the type of handles as
bull goodbull fair (makeshift cut outs in cardboard boxes)bull or poor
bull You also need to know if the lift is done in a standing or stooping position
43
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
DETERMINING THE MULTIPLIER VALUE (CONT)Once you have all these values use rArrRevised lifting equation to determine the RWL
Compare RWL to actual weight of the object
If the RWL lt lower than actual object weight
bull rArr determine which factor(s) contribute to the highest riskbull factors that are contributing the highest risk have the lowest
multiplier valuesbull modify the lift accordingly
44
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does not apply when liftinglowering
bull with one hand bull for over 8 hours bull while seated or kneeling bull in a restricted work spacebull unstable objects (eg buckets liquids containers)bull while pushing or pulling bull with wheelbarrows or shovels bull with high speed motion
(faster than about 30 inchessecond)bull extremely hot or cold objects or in extreme temperaturesbull with poor footfloor coupling
(high risk of a slip or fall)
45
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
APPLICABILITY OF NIOSH LIFTING EQUATIONIt does apply (mostly) with
bull two-handed lifting bull comfortable lifting postures and bull comfortable environments and non-slip floorings
Calculation of RWL using the formula
bull Indicates which of the six components of the task contribute most to the risk
bull The lower the factor it contributes more to riskrArrWhy is equation is called ldquorevisedrdquo
bull NIOSH published their first lifting equation in 1981bull In 1993 new revised equation was publishedbull It took into account new research findings and other variables that
not used in the first equationbull ldquorevisedrdquo equation can be used in a wider range of lifting situations
than the first equation
46
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESHorizontal Multiplier (HM)
bull Find horizontal distance (H in cm) from the midpoint between the ankles to the hands while holding the object
bull Determine HM from chart below
47
H = Horizontal Distance (cm)
HM Factor
25 or less 100
30 083
40 063
50 050
60 042
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESVertical Multiplier (VM)
bull Find the vertical distance (V in cm) of the hands from the ground at the start of the lift
bull Determine VM
from chart below
48
V = Starting Height (cm)
VM Factor
0 078
30 087
50 093
70 099
100 093
150 078
175 070
gt175 000
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESDistance Multiplier (DM)
bull Find the vertical distance (D in cm) that the load travelsbull Determine DM
from chart below
49
D = LiftingDistance (cm)
DM Factor
25 or less 100
40 097
55 090
100 087
145 085
175 085
gt175 000
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESAsymmetric Multiplier (AM)
bull Find the twisting angle (A) of the body while lifting in degrees (ordm)bull Determine AM from chart below
50
A = Angle (ordm)
AM Factor
90deg 071
60deg 081
45deg 086
30deg 090
0deg 100
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESFrequency Multiplier (FM)
bull Find the frequency of lifts (F) and the duration of lifting (in minutes or seconds) over a work shift
bull Determine FM from chart below
51
F=Time Between Lifts
FM Factor
Lifting While Standing
Lifting While Stooping
One Hour or Less
Over One Hour One Hour or Less
Over One Hour
5 min 100 085 100 085
1 min 094 075 094 075
30 sec 091 065 091 065
15 sec 084 045 084 045
10 sec 075 027 075 027
6 sec 045 013 045 -
5 sec 037 - 037 -
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
MULTIPLIER VALUESCoupling Multiplier (CM)
bull Find the quality of grasp (or coupling C) classified as good fair or poor
bull This depends on the body position (either standing or stooping)bull Determine CM from chart below
52
C = GraspCM Factor
Standing Stooping
Good (handles) 100 100
Fair 100 095
Poor 090 090
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
REVISED NIOSH LIFTING EQUATIONRevised NIOSH Lifting Equation
RWL = 23 Kg HM VM DM AM FM CM
Summary of steps
bull find out the values for the different multipliers for the MMH in question
bull solve for the RWLbull If RWL ge weight of the object handled rArr
bull task is safe
bull If the RWL lt weight of the object handled rArrbull task is dangerousbull task must be redesigned
53
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLProblem Statement Analyze the following work task A worker lifts 10 kg boxes from the conveyor to the cart ten times every minute for two-hours
54
6 sec
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWLSolution First calculate the recommended weight limit (RWL) for the task
1 Determine the weight of the loadWeight = 10 kg
2 Assess the six components of lifting task
55
H (Horizontal Distance) 20 cm
V (Vertical Distance) 75 cm
D (Lifting carrying Distance) 0 cm
A (Angle) 90deg
F (Frequency) 6 sec
C (Couplingquality of grip) fair
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL3 Select appropriate multiplier factors for each lifting
component from the appropriate tables
56
H (Horizontal Distance) 20 cm HM 1
V (Vertical Distance) 75 cm VM 1
D (Lifting carrying Distance)
0 cm DM 1
A (Angle) 90deg AM 071
F (Frequency) 6 sec FM 013
C (Couplingquality of grip) fair CM 1
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL4 Determine the Recommended Weight Limit for the task
RWL = 23 kg 1 99 1 071 013 1
= 2 1 kg
5 Compare weight of the load against determined weight limit for the task
weight of load (10 kg) gt RWL (21 kg)
6 Conclusion Task is Dangerous
57
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations
Assess which component(s) contribute(s) most to the risk
bull the critical factor is FM it is required to rethink the frequency rArrof lifting andor duration of task
Shorten the frequency of lifting by
a reducing the frequency of incoming boxes(ie increasing F) andor
b assigning additional workers to task andor
c shortening the time of the task to 1 hour
58
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL7 Recommendations (Cont)
59
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 1 EFFECT OF FREQUENCY FACTOR ON RWL8 Redesign the Task
Assess the six components in the redesigned task
Determine new RWL
RWL = 23 kg 1 99 1 071 075 1
= 121 kg
Compare weight of the box against determined weight limit for redesigned task
weight of load (10 kg) now lt RWL (121 kg)
Conclusionmost workers can perform the task safely (why most)
60
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 2 EFFECT OF HORIZONTAL DIST ON RWLProblem Statement
Analyze the following work task
A worker lifts 15 kg boxes from the table to the shelf five times an hour
Notice that there is a barrier between the worker and the box
61
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-
CASE 3 EFFECT OF VERTICAL DISTANCE ON RWLProblem Statement
Analyze the following work task
A worker lifts a 15 kg load of loosely-piled pieces of metal from the floor to the table five times an hour
62
- Biomechanics
- definition
- WHY
- Costs of Ignoring Ergonomics in the Workplace
- Case Shoulder Disorders
- Slide 6
- Human Systems
- Human SYSTEm
- Musculoskeletal
- 1 BONES you need to know
- extremities
- 2 Jaringan penghubung (Connective Tissue)
- Connective Tissue and Bones Functions
- Joints
- Muscle
- Slide 16
- Muscle Contraction
- BIOmechanics analysis (1)
- BIOmechanics analysis (2)
- Sign Conventions for Calculations
- latihan
- jawab
- LAtihan
- A Success Storyhellip
- Biomechanics (2)
- Lesson Overview
- What is Manual Materials Handling
- MMH Activities
- MMH Activities (cont)
- MMH Effect on Health
- MMH Effect on Health (cont)
- MMH Effect on Health (cont) (2)
- MMH Effect on Health (cont) (3)
- Establishing if a Lift is too Heavy
- Establishing if a Lift is too Heavy (cont)
- Calculating the RWL
- Calculating the RWL (cont)
- Calculating the RWL (cont) (2)
- Calculating the RWL (cont) (3)
- Determining the Multiplier Value
- Determining the Multiplier Value (cont)
- Determining the Multiplier Value (cont) (2)
- Determining the Multiplier Value (cont) (3)
- Determining the Multiplier Value (cont) (4)
- Applicability of NIOSH Lifting Equation
- Applicability of NIOSH Lifting Equation (2)
- Multiplier Values
- Multiplier Values (2)
- Multiplier Values (3)
- Multiplier Values (4)
- Multiplier Values (5)
- Multiplier Values (6)
- Revised NIOSH Lifting Equation
- Case 1 Effect of Frequency Factor on RWL
- Case 1 Effect of Frequency Factor on RWL (2)
- Case 1 Effect of Frequency Factor on RWL (3)
- Case 1 Effect of Frequency Factor on RWL (4)
- Case 1 Effect of Frequency Factor on RWL (5)
- Case 1 Effect of Frequency Factor on RWL (6)
- Case 1 Effect of Frequency Factor on RWL (7)
- Case 2 Effect of Horizontal Dist on RWL
- Case 3 Effect of Vertical Distance on RWL
-