Basic Conveyor Design & Maintenance

8/7/2019 Basic Conveyor Design & Maintenance

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T - SU552 Conveyor Maintena

Technical Paper T - SU552

BASIC CONVEYOR DESIGN & MAINTENANCEBy Neil Schmidgall



CONTENTS

ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

DESIGNING FOR MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

MATERIAL CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

BELT WIDTH, SPEED, AND CAPACITIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

SELECTING THE BELT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

IDLER SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

PULLEY AND SHAFT SELECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

BELT CLEANERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

TAKE-UPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

TRANSFER POINTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

SKIRTBOARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

IMPACT ABSORBING SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

EMERGENCY STOP SWITCHES AND CONVEYOR GUARDING . . . . . . . . .14

CONVEYOR MAINTENANCE SAFETY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

GENERAL SAFETY GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

GENERAL CONVEYOR MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17IDLER MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

INSTALLING A CONVEYOR BELT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

CONVEYOR BELT TRAINING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

LOADING THE BELT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

BELT TIGHTENING AND REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

CONCLUSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24



ABSTRACT

Maintenance is an important part of the life span of any piece of equipment.The harsh operating conditions experienced by aggregate conveyor systemsnot only increase the need for proper maintenance but also create a need fordesign considerations that facilitate proper maintenance. In many cases,proper design considerations may reduce the cost and time involved with con-veyor maintenance. Design considerations are not able to eradicate mainte-nance altogether however, in order to achieve longevity of the equipmentmaintenance must be performed correctly and according to the recommend-

ed maintenance schedule.

DESIGNING FOR MAINTENANCE

Producers and bulk material handlersspend millions of dollars every yearmaintaining conveyor systems.Oftentimes conveyor design does notprovide the means for ease of mainte-nance, and as a result, maintenance

may not be performed correctly, ontime, or at all.This eventually leads to agreater risk of component failure and aresulting loss of production.

Designing a conveyor to be mainte-nance friendly means providing ade-quate provisions for necessary servicefrom the onset. This means eliminatingproblems such as inadequate spacing,inaccessible positions, and other non-repairable configurations. The followingsections will illustrate some of the

design considerations that may deter oraid in conveyor maintenance.

MATERIAL CHARACTERISTICSWhen designing a conveyor, the type

of material to be conveyed is the firstitem to be taken into consideration.Theflowability of a material affects the sizeof the cross-section of material loadthat can be carried on a given beltwidth. Flowability is affected by materi-al characteristics such as: size andshape of the fine particles and lumps,roughness or smoothness of the mate-rial particle surface, the proportion offines and lumps present, and materialmoisture content. Considerationsshould also be given to the weight percubic foot of material, abrasiveness,

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and temperature. (Table 1)gives the weight per cubic foot,surcharge angle (Figure 1),and maximum conveying angle(Figure 2) of some commonlyconveyed materials.

BELT WIDTH, SPEED, ANDCAPACITY

For a given speed and materi-al density, the wider the con-veyor belt the higher the capac-ity of the conveyor. A belt mustbe wide enough so that thecombination of fines and lumpsdo not push the lumps too closeto the edge of the belt. (Table 2)shows the belt width necessaryfor a specific lump size, various

proportions of lumps and fines,and various surcharge angles.

Conveyor belt speeds dependupon the material characteris-tics, the capacity desired, andbelt tensions. Heavy materialwith sharp edges should beconveyed at moderate speeds.The sharp edges will causewear to the belt, particularly ifthe loading velocity of thematerial in the direction of belt

travel is lower than the beltspeed. Light, powdery materi-als must also be conveyed atlower speeds to reduce dustparticles, especially at loadingand discharge points on theconveyor. Fragile materials maydegrade at loading and dis-charge points, as well as whenmoved over idlers. Therefore,these types of materials shouldalso be conveyed at lowerspeeds. (Table 3) recommends

maximum belt speeds for com-monly conveyed materials.

As stated previously, beltcapacity increases with theincrease of belt width. It isimportant to know the tons perhour of material an end user



expects to move with a convey-or. If there is uniform feed to theconveyor, a cross section of thematerial loaded on the belt isused in calculating the capacityof a conveyor. The cross sectionof material must meet the follow-ing two conditions.

First that the material does notextend beyond to the belt edgeor the distance recommendedby CEMA, and secondly that thetop of the load does not exceedthe surcharge angle of loading

(Figure 1).

SELECTINGTHE BELT

The three elements of a con-veyor belt are the carcass, topcover, and bottom cover. Thecarcass of the belt must havethe tensile strength to withstandthe load on the belt, and it mustalso have the strength to with-stand the impact of materials inloading areas. Most carcasses

consist of multi-ply woven fab-rics (Figure 3 & 4). Heavierduty belt carcasses may containsteel cables for reinforcement.The yarns of a belt carcass thatrun parallel to the conveyor arecalled wrap yarns. These bear

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the tension of the belt. Thecross yarns of the belt carcassare called weft yarns and aid inimpact resistance and fabricstability.

There are four types of belt car-

casses. They are: multi-ply beltcarcasses, reduced-ply belting,steel-cable belting, and solid-woven belts. The multi-ply car-cass is usually made up ofthree or more plies cementedtogether by a rubber com-pound. Strength and load sup-port depend on the number oflayers, which is usually limitedto eight at the most. Reducedply belting may be used inplace of multi-ply belting. It

consists usually of fewer lay-ers than the multi-ply, but thelayers are made of syntheticfabrics of higher unit strength.A steel-cable belting carcassconsists of a single layer ofsteel cables imbedded in rub-ber. The all-gum type has onlycables and cable rubber, whilethe fabric-reinforced type hasone or more layers of fabricabove or below the steelcables (Figure 5). This type ofcarcass is best used for appli-cations where the tensionsrequired go beyond ply car-casses, and where take-uptravel is not long enough tocompensate for the high elas-ticity of ply carcasses. Solid-woven belts consist of a singleply of solid woven fabric usual-ly covered with a top and bot-tom cover made of PVC material. This type of carcass aids in abrasion resist-ance.

The main purpose of the top and bottom cover is to protect the carcass fromwear and impact damage. They also provide a friction surface to aid in thedriving of the belt. (Table 4) provides a guide to the required thickness of thetop and bottom belt cover.



The required length of a beltcan be computed by multiplyingthe conveyor length by 2 andadding the length needed towrap around the head and tailpulleys (Table 5). A gravitytake-up on a channel frameconveyor will require an addi-tional 6 feet of belt, while agravity take-up on a truss frameconveyor will require an addi-tional 10 feet of belt.

The ends of a conveyor beltmust be joined together(spliced) to create a continuousbelt. The two most commonways of splicing a belt are vul-canizing and using mechanicalfasteners. There are two types

of vulcanization: hot and cold.Using the hot method, the lay-ers of the belt are stripped in astair-step manner and over-lapped with glue and rubber. Aheated press is then used tovulcanize the belt, creating anendless loop (Figure 6). Thecold method laps the belt's lay-ers with glue that cures at roomtemperature.

The advantages to vulcanizing

belt ends are an improvementin splice strength, longer beltlife, and a lack of interferencewith belt cleaners, idler rolls, orskirting. The vulcanized splicewill eliminate material siftingthrough the splice as happenswith mechanical fasteners.

The vulcanized splice also hassome disadvantages, includinginitial cost and time required tocreate the splice. A vulcanizedsplice takes longer than usingmechanical fasteners andtherefore increases the con-veyor down time.

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Although vulcanized splices aremore expensive and time-con-suming, for permanent splicingof a conveyor belt vulcanizing isthe best choice.

The most important step in

using mechanical fasteners tosplice a belt is to recess the topand bottom splice pieces. Thetop and bottom covers areremoved down to the carcass.This does not endanger the beltstrength or integrity. The recessis needed to keep the fastenersfrom interfering with potentialcatch points.

Mechanical fasteners (Figure 7)are less expensive than vulcan-

ization and more easily applied.They are also the preferredmethod for making repairs to thebelt in the field, such as addingbelt length and patching holes ortears. Material leakage throughmechanical fasteners isinevitable. Over time, this maycause clean up problems andwill create the potential for dam-age to other conveyor compo-nents.

IDLER SELECTIONAll belt conveyor idlers have the

same purpose. They provideshape and support for the beltand minimize the power neededto transport material. Idler spac-ing affects both the shape andsupport of the conveyor belt. Idlers placed too far apart will not properly supportthe belt or enable it to maintain the desired profile. Idlers that are placed tooclose together will provide the necessary support and profile, but may add aprodigal expense to the conveyor. The main influences in idler selection are beltweight, material weight, idler load rating, belt sag, idler life, belt rating, and belttension. (Table 6) cites suggested idler spacing recommendations under rela-tively normal operating conditions when the amount of belt sag is not specifical-ly limited. This table also shows the recommended spacing for return idlers.

Proper idler roll diameter and size of bearing and shaft selection is based onload carried, belt speed, and operating conditions. To aid in the selection ofidlers, various designs have been assigned classifications illustrated in (Table 7).



PULLEY AND SHAFTSELECTIONThe standardization of pulleys

lends itself to the ease ofchoosing the correct pulley fora given application. The most

commonly used pulley is thestandard steel pulley shown in(Figure 8). Plain steel drumpulleys are best used in dryclean environments where trac-tion is not critical, and when noforeign material is present onthe return belt.

Conveyor pulleys may also becovered with rubber, fabric, orother material. This is referredto as lagging. Lagging on a

drive pulley provides anincrease in the friction betweenthe belt and the pulley. Laggingis also used to reduce abrasivewear to the face of the pulleyand to create a self-cleaningaction on the surface of the pul-ley. (Figure 9) illustrates a vul-canized lagged drum pulley.Typical grooving patternsinclude Herringbone, Chevron,and Diamond.

Plain rubber lagging on drumpulleys is typically used in snubapplications where traction isnot critical (Figure 10).Replaceable lagging is alsoavailable. The lagging strips arewelded to the face of the pulley,and can easily be replaced inthe field (Figure 11).

Wing pulleys are typically usedin tail pulley applications toreduce the build up of materialbetween the belt and pulley(Figure 12). Trapped materialsfall through the paddle-like for-mations of the pulley. Laggedwinged pulleys (Figure 13) areused in applications with abra-sive material present on thereturn side of the belt. It is natu-

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ral under these conditions forthe wing tips to wear premature-ly. The rubber lagging will addlife to the pulley.

Shafting is commonly consid-ered to be a part of the pulley

assembly since the strengthand rigidity of the assemblydepends on both of these com-ponents. When choosing shaftdiameter, it is important to con-sider both the shaft diameterrequired for strength and shaftdiameter required for deflection.Depending on the pulleyassembly, either strength ordeflection may be the decidingfactor of shaft diameter.

BELT CLEANERSCarry back is the fugitive

material that sticks to the beltafter the belt passes over thehead pulley and subsequentlycreates fugitive material pilesalong the underside of the con-veyor. Fugitive material is acostly problem, consideringthat many man-hours are spentcleaning fugitive material piles.In order to correct carry back, a

belt cleaner is used. This isusually a form of wiper orscraper device mounted nearthe discharge (head) pulley.A common type of belt cleaner

is the pre-cleaner. This is oftenreferred to as the primarycleaner and functions by scrap-ing off most of the carry backleaving only a thin layer of fineson the belt. The pre-cleaner ismounted on the face of the headpulley just below the discharge

trajectory. This allows the mate-rial scraped from the belt to fallwith the discharge materials.(Figure 14) shows a typical pre-cleaner.



Multiple cleaner systems arethe preferred method for elimi-nating carry back. The multiplesystems consist of a pre-clean-er and one or more secondarycleaners. In addition to theimprovement in belt cleaning,multiple belt cleaner systemsincrease the time intervalbetween scheduled mainte-nance times. Belt cleanersshould be positioned as closeto the head end as possible(Figure 15).

Secondary cleaners aredesigned to remove the thinlayer of fines left by the pre-cleaner. It's best to place thesecondary cleaner in contact

with the belt while it is stillagainst the head pulley. Thisenables the cleaner to scrapeagainst a firm surface.

There are several types of beltcleaners available to eliminatecarry back. The brush type canbe driven by the pulley motionor motorized (Figure 16). Thistype is effective on dry materi-als, as the bristles of the brushsweep the belt clean. The dis-

advantage to brush type clean-ers is the potential for build upon the brush's bristles.

Pneumatic type belt cleanerssend a stream of air across theface of the pulley to blow off thecarry back materials. They arebest utilized when moving drymaterials.The disadvantages ofthe pneumatic cleaners are theexpense of the continual airstream, and the creation of air-borne dust as the carry back isnot deposited in the dischargepile (Figure 17).

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There are two styles of wash-type cleaners that use water toclean the belt (Figure 18). Thefirst is a system that spays amisting of water on the belt inorder to make the scrapingprocess easier. The second typeuses a high-pressure wash tocompletely remove carry back.Problems occur with these typesof cleaning systems with theremoval of the sludge that is cre-ated. However, in some cases,the water-material mixture canbe returned to the material load.These systems also have thepotential for trouble under coldoperating conditions.

Return belt cleaner systems,

also known as v-plows, are usedto prevent large objects andtramp iron on top of the returnbelt from damaging conveyorcomponents. A low pressuremechanical scraping is used toremove the material from the belt(Figure 19).

TAKE- UPS

All conveyors need some formof take-up device in order to

ensure proper belt tension at thetail to prevent spillage of materi-als due to belt sag between theidlers, and to provide enoughtension to prevent slippagebetween the belt and the drivepulley. They also compensate forbelt shrinkage or stretch, andallow for extra belt length storagefor making replacement splicesin the belt.

The required take-up movementlength is determined by the typeof mechanism being used tostart and stop the conveyor, thefrequency of starts and stopswith a loaded belt, stretch char-acteristics of the belt, and run-ning tensions.



There are two types of take-upsystems, manual and automat-ic. The manual systems arepreferred when an automatictake-up is impractical. They arealso preferred for use on short,light conveyors where take-upsare not as critical.

The take-ups shown here aremost commonly found on beltconveyors. Window style take-ups (Figure 20) are best uti-lized on conveyors less than150 feet in length. The travellength of the take-up can be upto 36 inches.

Telescoping Tube type take-ups(Figure 21) can be used on

conveyors up to 150 feet inlength where headroom may bea concern. The travel length ofthe take-up can be up to 36inches. The Scissors type verti-cal gravity take-up (Figure 22)is also used when headroom isa concern. The travel length onthis take-up can be up to 8 feet.Gravity take-ups (Figure 23)are used on stationary convey-ors over 150 feet long andwhere vertical headroom is of

no concern.

TRANSFER POINTS

A transfer point is any point onthe conveyor where material isloaded onto or unloaded fromthe conveyor belt. The idealtransfer point would bedesigned to load the belt in thecenter and at a uniform rate.They should also reduce theimpact of the material falling onthe belt and maintain a mini-mum angle of inclination of thebelt at the loading point. Thedesign of discharge chutes andother loading equipment shouldtake these topics into consider-ation. Other factors such as

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capacity, size, characteristics ofmaterial handled, speed, andinclination of the belt should alsobe considered.

SKIRTBOARDS

Skirtboards are used to keeptransfer material on the belt afterit leaves the loading chute until itreaches belt speed. They areusually an extension of the load-ing chute and extend for somedistance along the conveyor(Figure 24). The distancebetween the skirtboard and theconveyor belt is critical.Skirtboards need to be placedhigh enough so that they nevercome into contact with the belt.

The gap between the belt andskirtboards should be as smallas allowable. The closer they aretogether the easier it is to main-tain a seal between them. Thegap between the bottom edge ofthe skirtboard and the belt isusually sealed by a flexible rub-ber strip attached or clamped tothe exterior of the skirtboard.

Skirtboard length can be basedon a rule-of-thumb of 2 to 3 feet

per 100 feet per minute of belttravel. The material should betraveling the same speed as thebelt when it leaves the loadarea.

IMPACT ABSORBINGSYSTEMSTransfer point structures can rapidly deteriorate due to loading zone impact

from heavy objects or material with sharp edges. Loading zone impacts alsocause wear and damage to the conveyor belt, weakening the belt carcass. Toaid in the prevention of this damage, transfer points should be designed to

lessen the height of the material drop. There are also devices made to reduceimpact at transfer points. Impact idlers may be used at the transfer point; theseare troughing idlers that have rubber-cushioned rollers to absorb impact.Impact cradles can also be positioned under the conveyor belt to absorbimpact at loading areas.



EMERGENCY STOPSWITCHES AND CONVEYOR GUARDINGEmergency stop switches consist of a pull-cable that

runs along the side of the conveyor and is connectedto a switch approximately every 100 feet of the con-veyor's length (Figure 25). The emergency stop

switch either shuts down the conveyor system orsounds an alarm if the cord is pulled, providing anextra safety device for operators and conveyor main-tenance workers.

Another safety device important in conveyor design isguarding. Machine guarding provides a safer workingenvironment. Some examples are shown below. Driveguards are used to cover v-belt drives, rotatingshafts, and jackshafts (Figure 26).

Return roll guards (Figure 27) are used to guardreturn idlers that are less than 7 feet from the groundor accessible by operators or maintenance personnel.Side guards (Figure 28) are used on transfer pointsto prevent access to pinch points and rotating compo-nents.

CONVEYOR MAINTENANCESAFETYBefore performing maintenance

on a conveyor, it is important to

be aware of general safetyguidelines that will help protectoperators and maintenance per-sonnel from injury. The first stepis to read the conveyor manufac-turer's operations manual.Manuals have instructions spe-cific to each conveyor on mainte-nance schedules, procedures,and requirements. The followingsections discuss safety proce-dures that should be followedbefore and during conveyormaintenance.

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GENERAL SAFETYGUIDELINESDo not allow anyone to operate

or perform maintenance on aconveyor until they have readthe manufacturer's operations

manual and are completelyfamiliar with all safety precau-tions.

Do not allow the followingpeople to operate or maintainthe conveyor...

- Children- Persons unfamiliar with the

equipment, or unfamiliar withsafe operating andmaintenance procedures forthe equipment.

- Persons under the influenceof alcohol, medications, orother drugs that canimpair judgment or causedrowsiness.

• Make sure everyone is clearof the conveyor before start-ing the belt, duringoperation, or maintenance.Never allow anyone to ride onthe conveyor.

• Do not leave conveyor unat-

tended while in operation.• Do not wear loose hanging

clothes, neckties, or jewelry.Long hair is to be placedunder a cap or hat. Theseprecautions will help preventyou from becoming caught inthe moving parts of theconveyor.

• Wear safety glasses, ear protection, respirators, gloves, hard hats, safetyshoes, and other protective clothing when required. Requirements for per-sonal protective equipment will vary depending upon conveyor placement

and material to be conveyed. It is the responsibility of conveyor operators tobe certain they make use of all necessary personal protective equipment.

• Buildup of materials on pulleys or idlers will lead to belt misalignment ordamage. When removing such materials, the conveyor must be stopped



and power controls must be locked out or tagged out.• The conveyor should not be used to handle materials other than those

specified as part of its design and manufacture. It is the operator'sresponsibility to be aware of the conveyor system capacities and operatethe conveyor accordingly.

• Make sure the operator's area is clear of any distracting objects. Keep work

areas clean, and free of grease and oil to avoid slipping or falling.• Periodically check all guards, shields, and structural members. Replace or

repair anything that could cause a potential hazard.

• When the belt is moving, the material travels at a speed sufficient to causeinjury. Do not start the conveyor until you are certain no one is exposedto the moving parts or to the material being discharged from the end of theconveyor.

• When doing maintenance work on structural parts or repairing any movingparts:

- Disconnect and lockout or tagout all power sources. Know OSHA require-ments.

- When welding is required, disconnect all power sources and connectground to point closest to welding area.

- Block all wheels to prevent the conveyor from moving, and block anyextended hydraulic cylinders to prevent them from moving or retracting.

• If any safety devices are not functioning properly, do not use the conveyor.Remove it from service until it has been properly repaired.

• Do not replace components or parts with other than factory-recommendedservice parts. To do so may decrease the effectiveness of the unit.

• Do not lubricate parts while the conveyor is running.

• Before starting engines within enclosed areas, be certain ventilation is

sufficient to avoid buildup of exhaust fumes.• Relieve any and all pressure before opening, repairing, or removing any air

pressure lines, hydraulic lines, valves, fittings, or seals. In the event of ahydraulic line rupture, stay clear of the area until pressure has beenrelieved. Clean up any spilled fluid before performing repairs in the area.

• It is the operator's responsibility to be aware of equipment operation andwork area hazards at all times.

• Operators are responsible to know the location and function of all controlsand indicators, including electrical power panels, hydraulic controls, motorcontrols, incline indicators, fuel and oil level indicators, belt scale controls,etc.

• Operators are responsible to know the location and function of all guardsand shields including but not limited to drive guards, pulley guards, and nipguards; and are responsible to make certain that all guards are in placewhen operating the conveyor.

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• Operators are responsible to be aware of safety hazard areas and followinstructions on warning, caution, or danger decals applied to the conveyor.

Safety hazard areas may include but are not limited to:- Pinch points at fold hinge areas- Pinch points at fold support areas- Pinch points where locking pins are used- Electrical control panels- Moving parts hazards on drives- Moving parts hazards where contact with belts and idlers is possible

GENERAL CONVEYOR MAINTENANCE• Carefully read through all safety instructions in the owner's manual.

• Return and trough idlers are either greaseable or non-greaseable. Checkgreaseable idlers to be sure they are filled with grease.

• Check to be sure the reducer is filled to the proper oil level.

• Check all other fluid levels.

• Check to be sure that skirtboards at loading points are installed and adjust-

ed.• Check equipment wiring-any and all wiring must be done by a qualified

electrician.

• Loosen and remove the v-belts by adjusting the torque arm reducer ormotor mount tension bolts.Turn the driven sheave by hand to determine thedirection of rotation. Run the drive motor or use a phase rotation indicatorto determine the drive sheave direction of rotation. If both sheaves are notrotating in the same direction, the unit must be rewired by a qualified elec-trician. Adjust the torque arm reducer or motor mount tension bolts to set v-belts at proper tension.

• If conveyor has multiple motors, steps should be taken to ensure the con-veyor load is shared equally between the motors. Use amperage meters to

measure the current drawn by the motors. Adjust the tension of the v-beltson the drives until the readings from the motors are equal. Be certain not toover tighten the v-belts. The drives should be checked periodically to see ifthe motor load is still balanced.

• When a belt scraper is used, be sure that it is properly installed, tensioned,and working.

• Be certain all guards and safety devices are in place and in working order.

• Visually inspect all hoses, lines, and belts for leaks, wear, and damage.

• Check and remove all tools and any foreign objects from the belt, particu-larly on the return run side where they may get between the pulleys andbelt. Grease on the belt should be removed immediately as it will

deteriorate the belt.

• Make certain no parts of the conveyor power, hydraulics, or moving partshave been locked out or tagged out. If they have, determine who placedthe lockouts, and have them remove the lockouts or tagouts beforestarting the conveyor.

• Walk completely around the conveyor, making certain no other personnelare under, on top of, or next to the conveyor. Warn anyone nearby that youare starting up the conveyor.



• After starting the conveyor, check all controls and indicators or gauges tobe certain they are in working order.

• Check the operation of safety stop lines and switches, if applicable, afterstarting the conveyor.

IDLER MAINTENANCE

All regreaseable idler series use the same principle: One shot-greasethrough, with a standard alemite 1627-B on one end and a bushing-pressurerelief fitting combination on the other end. If a change in the greasing side ofthe idler is needed after the idler is installed, the fittings are interchangeable.

• The idler rolls are filled with grease at the factory.Idlers that have been stored for longer periods of time need to be purgedand re-filled with grease.

• Idlers should be re-lubricated every 800 - 1000hours unless running in extremely dirty or wet conditions where more fre-quent greasing would be required.

• Do not over-grease! More idlers fail from over-greasing than from lack of

grease. Make sure all fittings are cleaned before and after greasing.• Re-lubrication should not be done when outside temperature is below freez

ing. Grease is sluggish and stiff at these temperatures and may cause internal damage.

• Roller grease seals are designed to hold in grease while there is pressurein the idler lubrication system. When grease passes through all three rolls,the pressure relief fit restricts the flow, causing internal pressure thatresults in grease being purged through the bearings. At a maximumpressure of 25 lbs., the relief fitting releases; thus protecting seals fromexcessive pressure. Leakage may occur around the outside ring of theseals. This is known as star burst or starring. This will flush thecontaminants away from the bearing.

General guidelines for greasing idlers:

Mild Conditions: Inside, protected from weather, dry material being con-veyed.Grease every 1000 hours.

Normal Conditions: Exposed to weather, but only dry material beingconveyed.Grease every 800 - 1000 hours.

Severe Conditions: Exposed to weather with water in material beingconveyed.Grease every 100 - 200 hours.

Extreme Conditions: Grease after every 40 hours of operation or more oftenif necessary.

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INSTALLING A CONVEYORBELTBelts are customarily pack-

aged in crates that can berolled from place to place.Crates and rolls are usually

marked with an arrow thatshows the direction in whichthey should be rolled.

When hoisting the belt roll, abar should be passed throughthe hole in the center of the roll.Fasten chain or cable to theends of the bar for lifting, anduse a spreader bar above theroll to prevent damage to theedge of the belt.

Always store the belt roll sus-pended on a tube or bar, orresting on the face width of thebelt. Storing the belt roll withweight on one edge maystretch the belt, making it diffi-cult to square at assembly andtrain during the initial operation.Belts should be stored in a dry,cool building. Never drop thebelt or store it on its edges.

Installation of the belt beginswith building a suitable stand

behind the conveyor and thenaligning the belting roll with theconveyor frame (Figure 29). Ifthe area behind the conveyorwill not permit this method ofthreading, the roll of belting canbe suspended above the con-veyor frame for threading.

Next, check the position of the side take-up bearings to make sure they arepositioned all the way to the retracted position. This will give you maximumtake-up ability after belt installation.Then check the belt to make sure the loadside (side with the thickest rubber covering) is facing up.

Most belting is shipped from the factory cut to length with additional allowancefor squaring ends for the splice.

The molded edges on new belts are not always straight and parallel.Whenever practical, it is recommended to square ends of belt with the cen-terline of the belt. Mark the center point of the belt using a light colored chalkor pencil (Figure 30). Then draw an average centerline using these points as



a guide. Locate two center points on the belt such that arcs will overlay. Drawthe arcs on the belt. Using a steel straight edge, draw the square line throughthe two arc intersecting points (A). Measure an equal distance (B) on bothsides of belt from square line to the cut line.

Next, position the fastener manufacturer's template on the belt (or fashionone yourself given the manufacturer's recommendation for fastener spacing)

and punch holes in the end of the belt for the fasteners. Always follow themanufacturer's recommendations as to the proper size of fasteners to be usedon any belt. Attach a clamping plate onto the end of the belt to enable an evenpull for threading the belt onto the conveyor.

Place the pulling plate on the bottom side of the belt so it will pass more eas-ily over the troughing idlers. Bolt the clamping plate to the belt through the fas-tener holes.The number of bolts should be proportionate to the amount of pullexerted.

Connect a cable or rope to the clamping plate. A braking system can bemade by using a belt clamp mounted on the conveyor frame to prevent beltrunaway while threading. Slowly pull the belt into position (near the tail sec-tion for easy access) with a block and tackle or similar equipment.

Attach 2 stretcher clamps roughly 3 feet from each end of the belt. Make surethe stretcher clamp on the squared end of the belt is parallel with the belt end.Remove the clamping plate and firmly attach the parallel stretcher clamp tothe conveyor frame.

Evenly draw the belt ends together, using a cable-jack or similar means, andpull the unsquared end of the belt over the top of the squared end until thecorrect belt tension is obtained. Maintaining this tension, create a centerlinefollowing the procedure described earlier, and mark a squared line where thebelt must be cut for the splice.

Place a wooden plank under the splice point to facilitate the cutting andpunching of holes in the belt. Cut the belt, position the fastener manufactur-er's template on the belt end, and punch holes for the fasteners.

The use of belt tape under the belt fasteners is recommended to help rein-force the splice area. Refer to instructions included with the belt fasteners forproper installation.

CONVEYOR BELT TRAININGBelt training is a process of adjusting idlers and loading conditions in a man-

ner that will correct any tendency of the belt to run off of center. Never attemptto train the belt by unequal adjustment of take-ups. The take-ups are only tobe used for keeping the tail pulley square with the conveyor frame and tomaintain belt tension.The training of a conveyor belt causing it to travel over the center area of

troughing idlers, pulleys, and return idlers is vitally important to trouble-freeoperation and low maintenance cost. Unless a belt itself is warped and curvedfrom improper manufacture, use, or storage, it is possible to train it for centralrunning. The following recommendations are basic to belt training procedures:

1. Level all frames crosswise as gravity will force the belt off-center if one sideof the conveyor frame is lower than the other (Figure 31).

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2. Square the tail pulley with the frame. Locate andmark point A at the midpoint of a conveyor crossmember. Next, measure an arbitrary distance frompoint A to locate a point X on the edge of the con-veyor frame.Then measure the same distance frompoint A to measure a point Y on the other edge ofthe conveyor frame. Line XY should now be squarewith the conveyor frame.

On the other side of the square line (line XY),locate a point B at the midpoint of a cross member.Measure the distance of BX and BY to verify thatline XY is square. Line BX and BY should be equal.

Clamp a straight edge to the conveyor frame direct-ly on top of the square line. Any component on theconveyor can now be squared by measuring fromthe straight edge equal distance on each side(Figure 31, distance C).

3. Square all troughing and return idlers with the

frame by measuring from the straight edge on bothsides of the conveyor and tighten theattachment bolts.

4. Check the belt splice for squareness. Check thebelt run on the return run side of the conveyor, orplace a large plywood board under the belt on theload side to get accurate measurements.

5. Run the conveyor empty and at reduced speed ifpossible. If the belt should show a side creep atonly the splice area and this progressed along the conveyor instead ofremaining at one point on the frame, the splice may not be square and mayhave to be redone. If necessary, resplice the belt. If you don't have sufficient

belt length to resplice after squaring the belt ends, you will have to add asection of belt. When adding belt sections, remove enough length from theoriginal belt to allow for a minimum distance of 3 feet between belt splices.

Once you have determined the splice is square, examine the return run sideof the conveyor for side creep first, beginning at the head end and workingdown to the tail. Make adjustments where side creep occurs as follows:

A. The point of maximum side creep (D) requires adjustment of a precedingidler (E) when you are facing in the direction of belt travel.

B. Loosen the bolts and pivot the idler (E) around its midpoint just as youwould turn a steering wheel to bring an automobile back to the center of itslane. Make these adjustments in small amounts; tighten the bolts and

make a test run after each adjustment to see the effect on side creep. Runthe belt at least three revolutions for the adjustment to take effect. If thepoint of maximum side creep changes, adjust the idler that precedes thatnew point.

C. When the slow running belt is centered, change to a higher speed (ifpossible). Load the belt with material and continue testing until normaloperating conditions cause no deviation from central running.



6. Examine the load run side of the conveyor following the belt travel from tailto head end. Make the same adjustments where side creep occurs.

LOADING THE BELT

After the conveyor has been thoroughly checked over and all belt trainingcompleted, the conveyor can be loaded. Start with a light load and gradually

work up to the load that the conveyor was designed to handle. When stoppingthe conveyor, operate until the belt is clear of material, especially at the end ofeach working day. During cold weather, material remaining on the belt willfreeze to the belt and may cause damage.

Rubber skirtboards are bolted to the trough to form the load centrally on thebelt, to prevent side spillage, and to prevent material from spilling out the backor bottom of the trough. Larger material spilling out the back of the trough haspotential to catch in the belt or damage the tail pulley. Skirtboards will requireadjustment or replacement as they wear.

Material should be stilled on the belt before it reaches the end of the skirt-boards. If the material particles are still tumbling as they pass the skirtboardends, belt speed may need to be adjusted, feed arrangement or rate may need

to be adjusted, or the skirtboards may need to be extended in order to avoidside spillage of material.

BELT TIGHTENING AND REPAIR

Conveyors with manual take-ups are equipped with side adjusting bolts at thetail end to maintain the necessary belt tension. With a wrench, loosen thetake-up side adjusting bolts to move the sliding bearing assemblies forward.Apply the proper tension to the belt to prevent slippage and excessive belt sagbetween troughing idlers, and then re-tighten the take-up side adjusting bolts.

Fasteners can be used to make quickrepairs to belt tears or to replace beltsections with new pads of the same

belting. Coat all exposed edges or cutswith rubber cementing compound toprevent any moisture or foreign mate-rial from entering the belt carcass andcausing further damage.

TROUBLESHOOTINGThe following is a troubleshooting

guide with suggested solutions tosome common conveyor problems.Match troubleshooting table (Table 8)to the corresponding number on the

troubleshooting key.

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Basic Conveyor Design & Maintenance

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