dyn.pptx

Train Dynamics

BYSyed Khaja Hussain B.Tech., M.B.A

Instructor/Rng/DTTC/GTL

DRIVING OF TRAIN

Easy• No steering is required

Complex• Hauling of an elastic mass

connected with a series of springs and couplers

• Reaction from the trailing stock are neither instantaneous nor fully controllable

3

Comparison between Driving a Road Vehicle and a Train

Concentration

Road Vehicle Train Normal concentration Sustained concentration

Road knowledge Not required Essential

Steering Essential Not required

Freedom to move/ stop Without restriction Vigil and alertness/ guided by signal

Braking Distance Short Long and variable

Responsibility Limited to self/ few persons Of hundreds of passengers and goods worth millions

Control Essential but easy Essential and complex due to trailing elastic mass

Engneering Mechanics

Statics

Syed Khaja Hussain Instructor/Rng/DTTC/GTL

Dynamics

KineticsKinematics

Fashion of motion Cause & Result of Motion

JerksSpeed

BouncingLurchingPitchingNosing

General Terms Used In Train Dynamics

• Tractive Effort• Adhesion• Friction• Draw Bar Pull• Vehicle Behavior • Slack• Run-in and Run-out• Train resistance

6

What is Tractive Effort ?

RAIL

Tractive Effort

Motion

The sum of forces at the rims of the driving wheels, which overcome the resistance, offered by the train, and cause it to move (or accelerate or maintained the speed, as the case may be)

8

What is Adhesion?

Adhesion

Tractive Effort

Motion

Adhesion can be defined by the following locomotive formula: % Adhesion = Tractive Effort (kg) X 100/ Locomotive Weight

126

5442%

10

Friction

When two moving surfaces, came in contact.

Resistance to motion, is called as FRICTION.

12

Draw Bar Pull

• Draw bar pull is the difference between the tractive effort and sum of the total rolling and the wind resistance of the locomotive at any operating speed.

• It is the useful force exerted by the entire locomotive in hauling trains

• Draw Bar Pull = Tractive Effort – Train Resistance

14

Linear and Rotational Motion of Vehicle in Three different Axes Vehicle Behaviour


Axis

Mode of Oscillation

Linear Rotational

X Shuttling Rolling

Y Lurching Pitching

Z Bouncing Nosing (also call as Yaw)

SHUTTLING ABOUT THE LONGITUDINAL AXIS

Compressive forces along the length of the train

ROLLING ABOUT THE LONGITUDINAL AXIS

Reduction in instantaneous wheel load

BOUNCING ABOUT THE VERTICAL AXIS


NOSING ABOUT THE VERTICAL AXIS

Increase in flange force

LURCHING ABOUT THE LATERAL AXIS

Increase in flange force

PITCHING ABOUT THE LATERAL AXIS


90


91

Different Parasitic Motion Generation due to the Effect of Track Defect

TRACK DEFECTS PARASITIC MOTION

X- level Rolling

Loose Packing Bouncing Rolling

Low Jt Pitching

Incorrect Alignment Nosing, Lurch

Slack Gauge Nosing, Lurch,

Variation in versine Nosing, Hunting

92

VEHICLE DEFECTS PARASITIC MOTION

Coupling Shuttling Nosing

Thin Flange WornWheel Hunting Nosing Lurching

Broken, Ineffective Spring Bouncing Pitching, Rolling

Side Bearers Clearance Rolling Nosing

Ineffective Pivot Nosing

Different Parasitic Motion Generation due to the Effect of Vehicle Defect

Concept of Slack :

Slack is inherent in any chain of vehicle.

Tightening connections can reduce it but it cannot be eliminated altogether.

Vehicles start moving at different time intervals because of slack.

Slack causes severe shock loads unless driving is properly adjusted.

95

Etc.

Free Slack

Slack is of Two Types

1. Free Slack 2. Spring Slack

It is the free relative movement of vehicles without change in the draft gear spring. It could be 1” to 2”.

Free Slack :

COUPLER FREE SLACK

It is distance a coupler can move if pulled manually by a bar.

In crude term it is “free travel” of couple. Free Slack

Free Slack

OPERATIONS OF A COUPLING SYSTEM

98

Etc.

Spring Slack : It is the additional slack caused due to spring compression and/ or elongation. It could be 4” to 6”.

Combined slack per vehicle could be 6”. Relative movement between loco and the last vehicle could be 30 ft for a train of 60 vehicles.

Free Slack Spring Slack

A good driver caters to all the slacks to avoid shock loading and consequent damage to components and/ or accidents.

100

Run-in and Run-out

When length and load of a train is more.

The stress and strain on draft gear will also be more.

Such train experience Run-in & Run-out.

When Run-in & Run-out occur ?

101

Run-in and Run-out

It may occur due to

- sudden application of brakes.

- change in gradient.

- sudden change in speed.

- in-built gap between locked knuckles.

Why Run-in & Run-out occur ?

102

Run-in and Run-out

The intensity of Run-in & Run-out is the major

cause for sudden JERK.

It results into breakage of coupling component.

What will be effect ?

103

Run-in and Run-out

When restarting the train, stopped on an up-gradient.

While restarting a train, after sudden application of brakes.

While accelerating a train, on up-gradient or plain, after a down gradient.

While accelerating a train, after releasing dynamic brake.

While applying sudden brake from rear brake van.

Practically, when it occur ?


• Tractive Effort• Adhesion• Friction• Draw Bar Pull• Vehicle Behavior • Slack• Run-in and Run-out• Train Resistance

105

Train Resistance

Train resistance contains : 1. Resistance on straight – level track

2. Journal Resistance :

i) Highest at starting. ii) Goes lower at 5 to 10 KMPH.iii) Remain constant at higher speed.

3. Air Resistance :

At high speed it consumes large portion of draw bar pull.

4. Flange Resistance :

Losses due to oscillation and vibration of the vehicle.

106

Train Resistance

5. Gradient Resistance :

Effort required to lift a train up on a gradient.

6. Curve Resistance :

Effort required to negotiate curve.

7. Acceleration Resistance :

Sum of the above three resistances subtracted from tractive effort available at the speed is the tractive effort available for acceleration.

107

Braking Distance

Braking Distance of Locomotive is the distance covered by the train after application of brakes, and is the sum of free running distance and retardation distance.

108

Automatic Brake (A-9) SSM and Throttle Handle (Slack Stretched Method)

Dynamic Brake Only SBM (Slack Bunched Method)

Dynamic Brake & SBM Automatic Brake (Slack Bunched Method)

Automatic Brake Only Modified SBM (Modified Slack Bunched Method)

Method of Braking

109

Speed Time CurveSpeed time curve of a train running on main line.

Starting up period or notching up period (o-t1)Acceleration Period (t1to t2 )Free Running Period or Negotiating (t2 to t3): Braking Period or Stopping

There are five distinct period :

110

Train Dynamics

Slack of trainTrack condition and geometry Train marshalling Driving technique

Depends on :-

Ensure safety PunctualityEconomy of operation Customer satisfaction

Resources to be mobilized :-

Hazards of Poor Enginemanship

Loss of Punctuality. Excess fuel consumption. Jerks/Rough riding. Train Stalling. Passing Signal at Danger. Brake Binding. Train Parting. Loco Failures. Damage to the Rolling Stock. Traffic dislocation Accidents.

Forces acting on a running train

FULLY UNDER DRIVER’SCONTROL

PARTIALLY UNDER DRIVER’S

CONTROL

NOT UNDER DRIVER’SCONTROL


FULLY UNDER DRIVER’SCONTROL

TRACTIVE EFFORT

BRAKING FORCE


PARTIALLY UNDER DRIVER’S

CONTROLMOMENTUM

TOTAL SLACKNESS


NOT UNDER DRIVER’SCONTROL

TRAIN RESISTANCES

Rolling friction

Journal Resistance

Flange Resistance

Wind Resistance

Gradient Resistance

Curve Resistance.

OPERATIONAL FEATURES;

WHAT ARE THE OPERATIONS

DONE BY THE DRIVER OF

A LOCOMOTIVE ?

APPLICATION AND REDUCTION OF

TRACTIVE EFFORT

APPLICATION AND REDUCTION OF

BRAKING EFFORT

(Apply/Release the Brake) (Open/Close theThrottle)

Parasitic Oscillation generated due to Operational features

LINEAR IN X- AXIS

Which is experienced as

JERK !!

What is a Jerk ?

INSTANTANEOUS CHANGE IN

SPEED

The intensity of a jerk is directly proportional to the mass and the square of the velocity (mv2)

DRIVER SHOULD BE ABLE TO OPERATE WITHOUT

JERK AND OVERSPEEDING

To avoid parasitic oscillations due to operational features

Slackness in Train

Free Slackness:– Gap between Couplings

Spring Slackness:– Due to Compression of Draft gear.

Total Slackness = Free slackness + Spring Slackness (2 + 4) = 6 Inches/Vehicle

Gradual Stretching of the slackness

Gradual Bunching of the slackness NO JERKS (Smooth RUN-IN & RUN-OUT)

121

Train

Handling

Methods.

Train Handling

1.THROTTLE

2. SELECTOR HANDLE ( Dynamic Brake)

3. A9 (AUTOMATIC BRAKE)

4. SA9 (INDEPENDENT BRAKE)

THROTTLE

THROTTLE

Rapid Notching Up To Higher Notches

Rapid Notching Down From Higher Notches To Idle.

Picking Up of 2nd Transition in WDM3A & Ist Transition in WDG 3A

at 7 th & 8th Notch

Notching Up Immediately After Releasing A9 By Watching The BP Gauge


EFFECT :• Due to which head-on portion Will get movement and rear portion

will not move thereby a chance of developing high tensile force and chance of train parting.

REMEDY :1. Apply SA9, open throttle to 1st notch allow the complete train to

stretch then open 2nd notch gradually release the SA9 allow the train to move at least 25 feet.

2. Give a gap of 30 seconds.3. While notching up to avoid wheel slip.4. While notching up from 4th to 5th maintain minimum 5 KMPH of

speed, 5th to 6th Notch 7 KMPH, 6th to 7th 11 KMPH, 7th to 8th 15 KMPH.

5. Feel the load on the loco by experience.

THROTTLE

THROTTLE




at 7 th & 8th Notch


Rapid Notching Down From Higher Notches To Idle

EFFECT :

• Due to which BUFF OR COMPRESSIVE FORCE will develop which may cause derailment and damage to the consignment.

REMEDY :

• Notch down slowly pausing between notch to notch and allow the train to bunch slowly thereby minimizing the development of compressive force.

THROTTLE

THROTTLE




at 7 th & 8th Notch


Picking Up of 2nd Transition in WDM3A & WDG 3A in 7 th & 8th Notch

• EFFECT :

• Due to which train will be bunched and immediately stretched due to dropping and picking up of GF contactor.

• REMEDY :

• Allow the transition to pick up on lower notches. Notch down immediately when transition picks up.

THROTTLE

THROTTLE




at 7 th & 8th Notch



• EFFECT :

• Since the loco is the 1st vehicle and the rear portion will have to get prescribed B.P pressure. Hence high tensile force will develop due to non realeasing of brakes.

• REMEDY :

• Notch up by watching Air flow indicator white needle to co-inside with the red needle or wait for minimum releasing time based on the application of A9.

Train Handling

1.THROTTLE




Dynamic Brake

• ADVANTAGES:

• Keeps the brakes block wear and wheel life more.

• It is more economical than A9 if you tally with the fuel consumed and brake wear.

• It is time saving because after using DB you have to wait for only 10 seconds to switch over to motoring, but for A9 you have to wait 90 to 120 seconds minimum based on A9 application.

• EFFECTIVE USAGE OF DB IS BETWEEN • 20-45 KMPH FOR GOODS AND • 20-60 KMPH FOR COACHING. • BELOW 20 KMPH THE EFFECT OF DB WILL BE FADING OUT.

Dynamic Brake

Selector

Rapidly Bringing from Motoring To Braking In Full Range

Rapidly Bringing from Braking To Motoring and immediately Notching UP


EFFECT :

Due to which BUFF OR COMPRESSIVE FORCE will develop as you are controlling head-on portion and the tail-end portion will come and bunch on the head-on portion. which may cause derailment and damage to the consignment.

REMEDY :

1. After closing the throttle, wait for 4 seconds, for the magnetic fields developed in the traction motors to decay.

2. Move the selector handle to big D, keep it for 6 to 30 seconds based on the type of load and grade, and allow the complete train to bunch.

3. Advance it slowly 4Ds at once move it to maximum duly watching load ammeter if it permits.

Dynamic Brake

Selector




EFFECT :

As the head-on portion suddenly gains the momentum and the tail-end portion is on controlling sudden stretching of train will take place thereby development of high tensile force which in turn causes parting.

The D.C traction motor will have high starting torque. If you notch up immediately after bringing the selector handle from braking to motoring, there is every chance of 4th notch out put on 1st notch due to the availability of 4th notch RPM (DB RPM) thereby high tensile force will develop which may cause train parting.

REMEDY :

• Move the selector handle slowly D by D to Big D.• Allow the train to stretch slowly then bring the selector to motoring.• Give minimum of 10 seconds after bringing the selector handle to motoring before

opening the throttle to the RPM to settle down.

Train Handling

1.THROTTLE




Automatic Brake -- A9

A9

Low Brake Pipe Pressure

Heavy Application

Applied Brake Too Fast

Running Release

Cyclic Braking

Short Brake Application

Low Brake pipe pressure• Low Brake pipe pressure:• In normal working condition if the Driver drops the BP more than 1.5

kg/cm2 it is called as Low Brake Pipe Pressure.

• If you drop B.P through A9 the pressure applied on brake cylinder is as follows.

B.P.Droppedin KG/cm2

Pressure applied on Brake Cylinder KG/cm2

4.5----0.5 1.24.0----1.0 33.4----1.6 3.8 + or – 0.1

0 3.8 + or – 0.1

Low Brake pipe pressure

EFFECT :

1. If the you drop the B.P more than 1.5 kg/cm2 which will have maximum effect on brake cylinder.

2. In normal working condition, if you drop more than 1.5 kg/cm2 the valuable compressed air is wasted.

3. Due to which the compressors are required to work more time thereby excessive fuel consumption will take place.

4. To recharge time (realeasing time )taken will be more thereby loss of running time.

5. Wear in the brake blocks will be more thereby life of brake blocks and wheel tyre will go down.

6. Causes brakes binding thereby flat tyre will occur.

REMEDY :

7. Try to control the speed by manipulating throttle and selector. Use A9 only when it is extremely required as per the procedure.