field service manual - rexnord

FIELDSERVICEMANUAL

IMPORTANT � Safety Instructions

Compliance with safety standards, including OSHA and otherFederal, State, local codes or regulations is the responsibilityof the user of the conveyor installation. Placement of guardsand other safety equipment in accordance with safetystandards is dependent upon the area and use to which thesystem is put. A safety study should be made of the conveyorapplication and guards should be installed whereverappropriate. �Safety Standard For Conveyors And RelatedEquipment� ANSI B20.1 is a guide for safe construction,installation, operation and maintenance of conveyors andrelated equipment.

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FIELD SERVICE MANUAL

SECTION DESCRIPTION PAGE

BELT CONVEYOR SAFETY INSTRUCTIONS . . . . . . . . . . . . . . . .PREFACE

I GENERAL BELT CONVEYOR INFORMATION

Typical belt conveyor layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2Typical belt conveyor schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

II BELT CONVEYOR INSTALLATION INFORMATION

Steel erection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4Machinery erection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Idler installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6Belt installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7Skirts, loading areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10Installation checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

III BELT CONVEYOR OPERATION INFORMATION

Conveyor start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Belt training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12Types of training idlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

IV CONVEYOR IDLER MAINTENANCE ANDLUBRICATION INFORMATION

Idler inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16Idler maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Idler lubrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17Idler lubrication techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Thru-greasing system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18Idler seal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

V BELT CONVEYOR TROUBLESHOOTING GUIDE

Table of common belt conveyor complaints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21Causes and cures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

VI IDLER REPLACEMENT PARTS IDENTIFICATION

Types of idlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

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The above layout illustrates a typical belt conveyorarrangement. The working points (W.P.) andcenterlines (CL) of the various conveyors are shown.

The drawings prepared by the Engineers andEquipment Manufacturers utilize this layout as abasis for foundation and conveyor designs. Inaddition, profile drawings must be used to showelevations of pits, tunnels, crusher house andtransfer towers and related chutes.

The accuracy with which these base lines andgrades are set has a direct bearing on the easeof erection of structural supports and conveyorruns.

Indicates the key dimensions from theconveyor centerlines and working points.

SECTION IGENERAL BELT CONVEYOR INFORMATION


C CONVEYOR

L

C CONVEYO

R

L C CONVEYORL

C CONVEYORL

C R.R. TRACKSBENT FOUNDATIONS L

BE

LT F

EE

DE

R F

OR

TR

AC

K H

OP

PE

R

RE

CLA

IM H

OP

PE

R F

EE

DE

R

RECLAIMHOPPER

TRACKHOPPER

TRANSFER TOWERW.P.

W.P.

W.P.

CRUSHERHOUSE

TYPICAL BELT CONVEYOR LAYOUT


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The layout shown below illustrates a basic beltconveyor. Unlimited variations of elevation,loading, discharge, idlers, their spacing, pulleysand accessories are possible.

THE BELT CONVEYOR

IDLER FUNCTIONSIMPACT: Designed to absorb impact and protect the belt from sharp edged material. Normally

spaced as close together as possible.

CARRYING: Support the belt and provide a trough to contain the material. Normal spacing 3 to 5feet.

TRAINING: Used to compensate for irregular loading, wind, and other varying conditions.Normally spaced no closer than 50 feet to the head or tail pulley.

TRANSITION: These idlers ease the belt from a troughed configuration to the flat pulley surfacereducing stress in the outer belt edges.

RETURN: Simply support the belt on its return journey. 10 feet spacing is typical.

PROBLEM-SOLVER: Since these contact the dirty side of the belt, they are normally placed prior to the beltcontacting another pulley and could be spiral, rubber disc, poly roll, or urethanecoated to resist material build up. In areas where abrasive wear is a problem, 1/4" roll

(Returns)

LoadingHopper

ReceivingHopper

Spiral orRubber Disc

ReturnIdlers

ImpactIdlers

TransitionSteelIdler

TransitionSteelIdlers

HeadPulley

BendPulleys

CarryingIdlers

CarryingIdlers

CarryingTraining

Idler

GravityTake-up

(optional)ReturnTraining

IdlerSteelReturnIdlers

ManualTake-upTail

Pulley

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The concrete base on which the conveyor will beinstalled must be set accurately. The anchor boltsmust be positioned exactly as shown on the generalarrangement drawing. If the location of the anchorbolts is not correct, the situation must be remedied.If the error is slight, it is possible to compensate byelongating the bolt holes in the steel pads. However,if the error cannot be corrected in this manner thebolts will have to be relocated.

Any sizeable error in locating the bolts would meanadditional trouble later in the erection of theconveyor. Tie in points could be missed, loading anddischarge areas misdirected and interference withexisting structures encountered.

See the example below and particularly note theconcrete base for anchor bolts. It is apparent that ifthe base is not located accurately there are manyareas which may cause problems as the erectionprogresses.

Erection should start at an anchored or lower endof the conveyor. Examination of the generalarrangement drawings will show the relationshipbetween working points and mark numbers. Themark number sequence and location must befollowed during field erection.

The working points shown represent the only tiebetween existing and proposed steelwork, buildingsand equipment. These points are critical andmust be located with accuracy to insure correctinstallation of conveyors.

Accurate alignment is necessary to insure a truerunning belt. All steelwork must be square, level andin line. Several sections must be bolted together onthe ground before lifting, taking care that themaximum allowable spans between supportingbents is not exceeded. Proper clearances must bemaintained. All shafting must turn freely with bolts inplace.

SECTION IIBELT CONVEYOR INSTALLATION INFORMATION


STEEL ERECTION

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The frames, trusses, etc. must be installed correctly.Temporary bracing is to be used wherevernecessary to handle loads which the structure maybe subjected during erection.

Standard construction of fabricated steel allowsfor minor variation in lengths and holelocations. Minor misfits are considered a normalpart of erection work. The accumulation oftolerances in foundations, grades, setting ofanchor bolts, etc. make it necessary to use driftpins, reamers, gas cutting and weldingequipment. Dimensional tolerances must becompensated for in fit-up.

When new truss sections or conveyor units aretied into existing units, it is expected that amajor amount of fit-up may be required. Theaccumulated tolerances are already built intothe existing equipment, making the job of tie-inand alignment a matter of detail fit-up.

No welding should be done until the structure hasbeen fit-up and properly aligned.

The conveyor stringers and decking should be setup, checked for centers, and leveled before beingpermanently secured to supporting members.

Before proceeding with the steelerection, a centerline for theconveyor should be established.This is done by stretching piano wirethe entire length of the frame (orportions of the frame on longconveyors.) Anchor the wire atconvenient points, a suggestedmethod is given below:

1. Secure an eyebolt to a piece of steel.

2. Locate the eyebolt on the approximatecenterline of the conveyor. Remember to keepthe eyebolt above the center roll of the idlers.

3. Fasten eyebolt bracket to structure.

4. Install a similar eyebolt bracket at the oppositeend (or at a convenient intermediate point if theframe has a bend, slope or reflex curve.)

5. String the piano wire, adjust on centerline, pulltaut, and secure.


SET IDLER LEVEL ACROSS WIDTH OF CONVEYOR

POSITION WIRE 1" TO 2"ABOVE TOP OF CENTER ROLL

SET IDLER PERPINDICULARTO CENTER LINE

1" TO 2"

AND ON CENTERLINE OF CONVEYOR FRAME

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MACHINERY ERECTIONThe basic working points that were used during thesteel erection should now be transferred to theconveyor frame to assist in the proper location andalignment of the pulleys and idlers, etc.

When located correctly, the piano wire affords aworking centerline from which measurements foralignment can be made.

The bearing pads should be leveled beforeinstallation of the pulley shaft assemblies. If shimsare necessary, they should be large enough to takethe entire machined surface of the bearing base.

Before installing any pulley shaft assemblies, checkthe general arrangement drawing for size and marknumbers.

After securing the head and tail pulley shaftassemblies, perpendicular to the line of belt travel,parallel with each other and level, it is good practiceto set stop blocks against the bearings and weldthese blocks to the steel. The holes in the bearingbase are slotted and the stop blocks will prevent thebearings from shifting.

Install bend pulleys and the gravity take-up pulleyas shown on the general arrangement drawing.

Automatic Take-UpBe sure that the pulley turns freely and that the take-up frame slides easily to compensate for variationsin belt tension. Use recommended amount ofcounterweight and adjust if necessary.

Manual Take-UpAdjust the take-up so that the belt tension issufficient to insure that the loaded belt will operateover the terminal pulleys without slipping. Excessivetake-up on the belt will cause undue strain onshafting, bearings and belt splicing. It will also tendto keep the belt from troughing properly.

IDLER INSTALLATIONStorage and PreparationIf idlers and other equipment arrive on the job site inadvance of their installation, some protectivemeasures should be taken against exposure to theweather and other adverse conditions.

Rex idlers are normally shipped on skids or pallets.These should be stored so that water will notcollect around them and should be covered ifstored outdoors.

Before installation, idlers should be inspected andcleaned of any foreign matter that may haveaccumulated during storage or transit. Foreignmatter on idler rolls can cause damage to the belt.

Troughing IdlersWhen installing a conveyor system, troughing orcarrying idlers should be installed first.

Starting at the tail end of the conveyor, the firststandard troughing idler should be located anapproximate distance from the centerline of the tailpulley equal to one belt width for 20° troughedidlers, 11/2 times belt width for 35° troughed idlers,and twice the belt width for 45° troughed idlers.

It is good practice to use a 20° troughing idler as atransition idler for the first and last idler when using35° troughing idlers, and both a 20° and a 35°troughing idler when using 45° troughing idlers.

Place idlers in position by sliding them in thedirection of belt travel firmly against the mountingbolts and lightly tighten. Final alignment requiresthat the center of all idlers are in a straight line,perpendicular to the line of belt travel, properlyspaced, and level. When alignment is complete, boltthe idlers securely in place.


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Return IdlersAfter the carrying idlers have been set in place, thereturn idles should be installed. The return idlersmust be installed perpendicular to the conveyorcenterline and level. Leave the training idlers outuntil the belt has been properly trained.

Single return idlers are used where stickymaterials adhere to the belt, where a corrosiveenvironment is present or abrasive wear is aproblem. Their unique construction minimizes beltfleet and damage to the return belt due to materialbuild-up on the idler rolls. Spiral return idlers canbe used for belt travel in one direction only.Install only as instructed on installation instructiontag.

BELT INSTALLATIONPosition of Take-UpThe screw take-up should be set about 3" from thefull forward position (toward head end of conveyor).The gravity take-up frame should be positionedapproximately one foot below the upper stop on thetake-up guides. The dimension should be measuredfrom the bottom of the upper stop of the take-upframe.

Installation of BeltOn conveyors with short centers (200-300 feet),there should be no problem in removing all of theslack from the belt.On conveyors with long centers, it may benecessary to take two hitches while stringing thebelt; one to remove slack on the return side, � thena second hitch on the carrying side. It is important toremove as much slack as possible while stringingthe belt. The belt will stretch during its initialoperation, which points out the importance ofstringing a tight belt initially.

Handling of BeltsConveyor belts are usually packaged in cylindricalcrates which may be rolled from place to place. Allcrates and rolls are marked with an arrow showingthe direction in which the crate or roll should berotated.When hoisting the belt, a bar is passed through thehole in the center of the roll. Chains or cableslooped around the bar should have a spreaderabove the roll to avoid damage to the belt edges.Never store the belt on its edges. The belt shouldalways be suspended on a tube or bar if it is to bestored for any length of time.

Stringing and Splicing of BeltThe roll of belting should be brought to a locationwhich will allow ease of stringing. Mount the roll on ashaft and suitable structure for unrolling andthreading on to the conveyor. (See sketch nextpage.)

NOTEA temporary flat idler roll should be installed atthe bend point of the belt.

Conveyor belting is normally rolled at the factorywith the carrying side out. Consequently, the beltmust lead off the top of the roll if it is being fed ontothe carrying idlers. If the belt is being fed onto thereturn idlers, it must be lead off the bottom of the roll.


BELT TRAVEL

8

In some cases, such as in mines, where head roomdoes not permit maneuvering a roll, the belt mayhave to be pulled off the roll and reefed. Extremecare should be exercised to see that the loops havelarge bends to avoid kinking or placing undue strainon the belt. Weight should never be placed on thebelt when it is in this position. (See sketch.)

Before stringing the belt, the erector should makecertain that the thickets rubber cover of the belt willbe on the top or load carrying side.

Holes or notches should not be cut through thebelt for attaching a pull rope. A clamping deviceshould be used to distribute the force across thebelt. (See sketch.)

Since the clamp must pass through narrow opening,it is usually made of 1/4" plate approximately one-half of the belt width. The bolts are placed throughboth plates at 6" intervals and 2" from the belt end.A rope or cable is attached to this clamp by meansof an eye welded to the plate. The rope or cable isthen threaded over the conveyor and attached tosome suitable towing device to pull the belt.

Installations having a relatively high degree of slope(12 degrees or more) must be handled with moreprecautions against runaway. As the belt is fed on,the tension at the roll tends to build up due to theweight of the belt on the slope. Therefore, somemethod of braking is required. Customary practiceis to use a belt clamp, mounted on the conveyorstructure, through which the belt is threaded. Wherethe slope is very long, additional clamps should beused, spaced approximately 1,000 feet apart.

The final splice should be made at the bottom of theslope where the splicing tension required is lowest.Making the final splice at the top is possible, but ahigher tension will be required.


TEMPORARY FLAT ROLL AT BEND POINT

ABOUT 1/2BELT WIDTH

1/4 PLATE

WELD EYE TO PLATE

PULL

BACK-UPPLATE

NO WEIGHT TOBE PLACED ON TOP

KEEP BENDS LARGE TOPREVENT BREAKING CARCASS

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Tensioning the BeltOnce the belt has been pulled onto the conveyor itmust be tensioned prior to splicing to avoid initialdissipation of take-up travel. The tensioningoperation takes place at the location where the lastsplice will be made. Clamps are placed on each endof the belt. These are made of hard wood and havea clamping surface as indicated. (See sketch.)

Tension is applied by means of come-alongs whichare hooked on each end of the belt clamps.

Certain basic statements can be made aboutsplicing tensions:

1. Belts, which are clamped off on one end andtensioned by pulling in one direction only,require more splicing tension than those pulledin both directions.

2. Slope belts spliced at the top of a slope requiremore splicing tension than those spliced at thebottom.

3. Slope belts having an anti-rollback whichcannot be released must be tensioned bypulling in the direction of belt travel only. Use aseries of clamp-off devices to take out belt slack.

4. Check the belt frequently during tensioning tomake sure that the belt is free and not bindinganywhere.

Short belts may easily have too much tensionapplied and thus have a harmful effect on the pulleybearings as well as the belt.

On a conveyor with a gravity take-up, the spliceshould be made near the take-up.

It is recommended that the belting manufacturersdetailed instructions are followed when making theactual splice.


BELT CLAMP CONTOUR

PULL HERE

REMOVE SLACK

PLYWOOD

SPLICING AREAPULL HERE

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Mechanical FastenersEach box of mechanical fasteners is complete witha set of instructions and a list of tools required tosplice the belt.

Belt ScrapersA scraper is located at the head end of a beltconveyor to remove material from the belt and intoa receiving chute. A counterweight or spring keepsthe scraper blade against the belt. Proper fieldadjustment is required periodically.

RUBBER SKIRTS-LOADING AREAS

When setting the steel for the loading skirts, use aboard as a gage for clearance between the idler rolland the bottom of the steel skirt.

After installation of the conveyor belt, install therubber skirt. The rubber should lay on the conveyorbelt with a minimum of pressure.


APPROXIMATELY 3/4" PLUSTHICKNESS OF CONVEYOR BELT

STEEL SKIRT

GAGEBOARD

RUBBERSKIRT

Clearance to beadjusted and held whensetting steel at skirt plate

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The following items should be inspected beforeinitial operation:

1. Head and foot shafts parallel to each other andpulleys in-line.

2. All bolts properly tightened.

3. Idlers secured in-line.

4. Reducer filled to proper oil level.

5. Oil in chain guards, S.A.E. #30, to proper level.

6. Correct motor rotation.

7. Check and remove all tools and any otherforeign objects from the belt, particularly on thereturn side where they may get between theterminal pulleys and belt. Grease on the beltshould be removed immediately as it willdeteriorate the belt.

8. Counterweight installed and gravity take-upblocking removed.

9. Screw take-up pulled back and pulley square.

10. Belt wipers installed and properly adjusted.

11. Emergency stop cords and switches installed.

12. Bearing stop blocks welded to terminal framesteel, or adjusting screws tight up againstbearing bases.

13. Flop gates operative and in correct position formaterial flow.

14. Rubber skirting at loading points installed andadjusted.

INSTALLATION CHECKLIST


For Notes

12

CONVEYOR START-UPBefore actual start-up of a conveyor system,electrical controls should be checked to insure thatthe entire system can be stopped quickly in case ofemergency.

During initial start-up, the conveyor should bejogged on and off until the belt has made severalcomplete revolutions. During this period, make athorough check of all equipment to determineproper adjustment and function.

BELT TRAININGBelt training is a process of adjusting idlers andloading conditions in a manner which will correctany tendency of the belt to run off. DO NOTATTEMPT to train the belt by unequal adjustment ofthe screw take-ups.

A misaligned conveyor will cause the belt to run-offto one side. The belt will tend to creep to the sidethat makes first contact with the idler roll. Thiscondition can usually be corrected by adjusting afew idlers to change th contact points. The returnside should be adjusted first, starting at the headend. Note the run-off point and adjust a few of thepreceding idlers. The adjustments are made byshifting the idlers so that the belt contacts the rollopposite the run-off. (See sketch.)

A slight adjustment on a number of idlers isrecommended.

Repeat this procedure at other points along the belt,if necessary, until the return side is running true.

The carrying side can then be adjusted by using thissame procedure starting at the tail end andproceeding toward the head end.

Belt training may be improved by tilting thetroughing idlers. (See sketch.)

Tilt the idlers forward a maximum of 2° in thedirection of belt travel. This is done by placingwashers under the back of the mounting pads.

SECTION IIIBELT CONVEYOR OPERATION INFORMATION


ADJUSTMENT

BELT TRAVEL(AFTER ADJUSTMENT)

PERPENDICULARTO BELT LINE

BELT RUN OFF(BEFORE ADJUSTMENT)

TROUGHING IDLER STAND

WASHER

2˚ MAXIMUM

DIRECTION OF TRAVEL

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Return idlers cannot be tilted, however, by shiftingtheir axis, they can be used to provide a correctiveeffect.

This can be done by slightly advancing and raisingthe alternate ends of the return rolls nearest the tailpulley. This can be done for expediency on atemporary basis. If this area is a training problem, aself-aligning return idler should be installed about

the 2nd or 3rd idler from the tail pulley.

NOTEShifting or tilting of idlers for belt training canonly be used for belts traveling in one directiononly. This remedy cannot be used for reversingbelt conveyors.

Training Loading BeltOnce the belt has been properly trained whilerunning empty, the belt must be checked whencarrying a full load.

A properly trained belt will run true under loadedconditions. A loaded belt that runs off center is usuallycaused by improper loading. Chutes should distributethe load evenly and on the center of the belt.

LoadingStart with a light load and gradually work up the loadthat the conveyor was designed to handle. Checkchutes to see that the material is being directed ontothe center of the belt.

Off-center loading is harmful to the belt, idlers, andshafting. An off-center load will affect belt alignmentin that the belt will run off center. A centered load willmaintain belt alignment. (See illustration below.)

The loading point of a belt conveyor is the criticalarea. Here the conveyor is subjected to maximumabrasion and impact. The desired condition is toload the material at the same speed and direction oftravel as the belt, with a minimum amount of impactand on the center of the belt.

The skirts must be adjusted to prevent spillage andto keep the load centered on the belt. The maximumrecommended distance between skirtboards is two-thirds the width of a troughed belt. It is desirable toreduce this spacing to one-half the width of thetroughed belt when conveying free flowingmaterials.

The skirt length should be designed to prevent sidespillage until the material is at rest on the belt. If thematerial is still tumbling as it passes the skirt end,the skirts should be lengthened.


14

TYPES AND ADJUSTMENT OFTRAINING IDLERSA properly aligned and centrally loaded belt willtrack in the center of the idlers without using trainingidlers. Training idlers are used to compensate foroccasional irregular loading, the effects of wind, andother varying conditions.

TROUGHING TRAINING IDLERS,POSITIVE TYPETroughed training idlers are installed along theconveyor length, as required, but not closer thanfifty feet from a pulley. Positive type can be used onbelts traveling in one direction only.

TROUGHING TRAINING IDLERS,ACTUATING SHOE TYPEActuating shoe type can be used on reversing beltsand on belts with traveling trippers or stackers.

RETURN TRAINING IDLERS,POSITIVE TYPEReturn training idlers are installed along theconveyor length as required, but not closer than fiftyfeet from a pulley. Positive arm and inclined pivottype can be used on belts traveling in one direction

only.

RETURN TRAINING IDLERS,

ACTUATING SHOE TYPEActuating shoe type can be used on reversing belts.

RETURN TRAINING IDLERS,

INCLINED PIVOT TYPEInclined pivot type can be used on belts traveling inone direction only.


15

SIDE GUIDE IDLERSSide guide idlers do not train a belt. They are usedto prevent a belt from running off the pulleys and toprevent the belt from damage caused by theconveyor structure and other objects.

They should be installed so that they do not touchthe belt edge when it is running normally. If the beltruns against side guide idler rolls continuously, beltdamage can occur even if the rolls rotate freely.

TRAINING IDLER PIVOT ADJUSTMENTAdjustment of the pivoting action of training idlerscan be made by loosening the two bolts and movingth angel in or out to change the amount of allowablemovement. The pivot stop is set at the factory fornormal operation.


CENTRAL PIVOT FOR TRAINING IDLERSGeneral InformationHeavy cast housing and cap. Bearing cavitypregreased and sealed for long bearing life. Opposingtapered roller bearings to handle radial and thrust

PIVOT CAP

ADJUSTINGANGLE

LOCKINGBOLTS

HUSKYPIVOTPIN

OPPOSING HEAVY DUTYTAPERED ROLLER BEARINGS

SEALING CAP BEARING RETAINERSLOCKED IN PLACE

LARGEGREASERESERVOIR

16

Regularly scheduled inspections of conveyorsystems is the best preventive maintenancepossible. Problem areas can be detected andcorrected before damage occurs to the belt orequipment.

A check of the loading areas is the best place tostart. Loading chutes should be delivering materialto the belt evenly and centered on the belt. Unevenor off-centered loading is the greatest cause ofproblems on any belt conveyor.

Noticeable vibrations should be located andeliminated as this may loosen mounting bolts andcause the idlers to shift. Misalignment problemsmust be corrected at once.

Walking the length of the conveyor installationand checking the idler rolls to be sure that theyare all turning freely and smoothly, with noexcessive end play, is recommended as part ofthe periodic inspection.

Roll failure can, in most cases, be found before theroll stops rotating. Unusual noises are an earlyindication of roll failure. Stalled rolls must be clearedimmediately. If rotation is retarded by material build-up against the roll, clear immediately. Stalled rollsnot only drain energy from the system, but alsocause excessive roll shell and belt wear and shouldbe replaced.

First, stop the conveyor and lock out the powerswitch.

Then remove and replace any rolls not operatingproperly. Faulty rolls can be disassembled andrepaired.

Watch for unusual wear patterns on the idler rolls,which can be caused by off-centered loading or idlermisalignment.

Check idler alignment and adjust as required,remember to retighten mounting bolts. If off-centered loads occur make corrections to chutework.

Check for material build-up on idler rolls, particularlythe return rolls as these are in direct contact with thecarrying side of the belt.

If build-up occurs check the belt cleaner to be surethat it is operating properly. If a belt cleaner has notbeen installed, it is recommended that one is placedin operation as soon as possible.

Excessive build-up on idler rolls will cause damageto the belt. Shut down the conveyor, locking out thepower switch and clean up or repair immediately.Rex spiral or rubber disc return idlers are designedto keep material build-up on the rolls to a minimum.

Check all training idlers to see that they are pivotingfreely.

CONVEYOR IDLER INSPECTION

SECTION IVCONVEYOR IDLER MAINTENANCE AND LUBRICATION INFORMATION


KEEP CLEAN

KEEP CLEAN

17

Clean up any spilled material that might restrict theidler from pivoting freely and free any frozen pivots.

Check to be sure all lubrication fittings are in goodcondition. Replace where needed.

CONVEYOR IDLER MAINTENANCEInspection and MaintenanceA scheduled maintenance program, followed faithfullyby trained people, can usually help avoid costlyinterruptions in production and repairs to equipment.Many operators make a cursory check at least oncea day to find obvious problems. A morecomprehensive inspection is made at period intervals.

Inspection should include checking the following:

1. Inspect the belt for breaks or cuts or forindications that the belt edge is rubbing.

2. Make sure center of the belt is running on thecenter of the idler.

3. Loading areas should be checked to see thatmaterial is being loaded evenly, and on thecenter of the belt.

4. Rubber skirts on chutes and skirt plates areadjusted to prevent spillage.

5. Belt cleaners are properly adjusted and working.6. Rex idlers are designed to be self cleaning.

Accumulation of material must not be allowed toprevent idler rolls from rotating or preventtraining idlers from pivoting.

7. Check to see that all idler rolls are rotating. Astalled roll will cause excessive roll shell andbelt wear and should be replace.

CONVEYOR IDLER LUBRICATIONAll idlers are prelubricated at the factory and areready for operation. All external lubrication lines(either furnished by Rexnord or added by thecustomer) should be filled with grease wheninstalled to insure that the idlers will get greasewhen lubrication cycle is started.

Under normal conditions, relubrication should beevery 4000 to 6000 hours until a clean bead ofgrease appears around the final opening of eachseal. (See sketch.)

The lubrication cycle can be lengthened inapplications where operating conditions are clean,dry, of moderate temperature and slow speed. Thecycle should be shortened in applications wheresevere dirt, high humidity, elevated temperatures,high speeds, free water, prolonged shutdown, or

other extreme conditions are encountered. Periodicinspection during the first few years of operationswill provide the best determination of requiredrelubrication frequency.

Rex idlers are greased at the factory with LithiumEP grease with a NLGI #2 consistency having thefollowing characteristics.

1. Lithium soap base2. Mineral oil3. Worked penetration 265-295 @ 77°F4. Operating range of +225°F to �10°F5. Bleed rate 3% maximumIt is recommended that an equivalent grease beused. When using any other type of grease, it isimperative that it be compatible with the originalgrease.

When lubricating idlers, the use of high pressureequipment is not only unnecessary but is actuallyundesirable unless used with great care. Highpressure may cause damage to bearings and seals.It is recommended that a VOLUME TYPE GREASEGUN BE USED; one that delivers an ounce ofgrease per seven to ten strokes of the lever.


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All fittings should be wiped clean before lubricatingso as not to introduce dirt.

IDLER LUBRICATION TECHNIQUESRex idlers should be lubricated with a high volume-low pressure gun to insure purging of all seals. Thistype of grease gun delivers an ounce of greaseevery 7 to 10 pumps. High pressure-low volumeguns should not be used because they do notdeliver enough volume of grease per stroke topurge all seals. The greasing system relies on agenerous volume of grease per stroke to create thepressure distribution necessary to purge all seals.

An ounce of grease is normally required to purge aCEMA B or C idler. (1.5 oz. for CEMA E.)

A good grade of NLGI #2 grease with low bleedcharacteristics should be used. Mobil Oil Companygrease Mobilux EP2 or equal is recommended.

REXNORD PATENTEDTHRU-GREASING SYSTEMMost customers recognize the need to lubricateidler bearings in order to extend idler life.Relubricating flushes out contaminants especiallythrough the labyrinth (clearance type) seals.

The most positive way to assure that greasereaches each bearing is to have an individual fittingon each bearing. But vulnerability to damage,added cost, and inconvenience of multiple greasepoints make this impractical.

One-point thru-greasing is now available from mostidler manufacturers. This system is essentially achannel through the center of the idler with outletsto the six bearings (Fig. 1). A grease fitting at one orboth ends of the idler is used to introduce freshgrease. A short tube is generally used to transfergrease from roll to roll.

One-point thru-greasing is successful only if thesystem can meter grease equally to all six bearings� a proven feature of Rex idlers.

Radial hole size becomes critical when using open,purge type seals. A large diameter radial hole allowsmost of the grease to be released through the firsttwo labyrinth seals. Pressure at the third, fourth, fifthand sixth seals is practically zero � as shown inFigure 3. A small diameter radial hole restrictsgrease flow and produces a more uniform pressure(Figure 5).

Figure 2 is a schematic diagram of a typical one-point thru-grease system. A pressure-distancediagram (Fig. 3) shows a momentary high pressureat bearing #1 and some residual pressure atbearings #2 and #3, but almost no pressure frombearing #4 on. Without a pressure differentialbetween the inside of the shaft and the outside,grease will not flow through the bearing cavity.Pressure can be increased throughout the systemby blocking off all exists. Figure 4 shows whathappens to a hypothetical system with all outletsblocked.


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Figure 5 diagrams pressure-distance in a systemwhere small diameter radial holes meter grease toeach bearing. In the system, the radial holes aresmall enough to restrict grease flow into the bearingcavities. This causes a momentary high pressurethroughout the system. This high pressure isrelatively uniform from end to end, and release ofgrease through the small radial grease holes is alsorelatively uniform. The large diameter, reinforcedrubber connecting tubes tend to �give� a little, actingas �surge tanks� to smooth out the pressure peaksand assure flow into the six bearings. The tube canbe seen in Figure 6.


BEARING #1 #2 #3 4 #5 #6

GREASE

FLOW

PR

ES

SU

RE

IN S

HA

FT

PR

ES

SU

RE

IN S

HA

FT

PR

ES

SU

RE

IN S

HA

FT

Figure 2

LENGTHLARGE RADIAL HOLE – FAR END PLUGGED

Figure 3

LENGTHNO RADIAL HOLES – FAR END PLUGGED

Figure 3

LENGTHSMALLRADIAL HOLE – FAR END PLUGGED

Figure 3

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REGREASABLE IDLERSBetter Protection Against Abrasivesand MoistureRex offers a special combination labyrinth andprotective outer shield for your operatingenvironment. This seal has five hard-to-get-throughpassages filled with grease to block contaminantsfrom the roller bearings. The outer and inner sealsare close tolerance injection molded nonmetallic.The labyrinth/shield seal is particularly excellent forlong overland horizontal conveyors, because of itslow friction torque or for applications where water ispresent or when frequent washdowns are required.

FACTORY-SEALED IDLERSBetter Protection Against Abrasivesand MoistureRex offers a special combination of labyrinth andprotective outer shield for your operatingenvironment. This seal has five hard-to-get-throughpassages filled with grease to block contaminantsfrom the roller bearings. The outer and inner sealsare close tolerance injection molded nonmetallic.The factory sealed idlers feature the samelabyrinth/shield seal as the regreasable idlers butwith an added internal wiping seal to further delaythe penetration of contaminants. This product willprovide excellent service in relatively cleanenvironments or where minimum maintenance canbe provided.


REX �G� SEALREGREASABLE OR FACTORY SEALED

ROTATINGPARTS

GREASE

ROTATINGPARTS

GREASE

WIPER

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Any belt conveyor installation can be subject to awide variety of difficulties which may become costlyin terms of replacement and plant downtime unlessthe problem is quickly diagnosed and corrected.This guide is intended to point out the majority ofbelt conveyor problems and set forth their probablycauses and cures.

Locate your specific problem in the �complaint�column below and note the numbers to the right.They represent the most likely causes for theproblem, in order of probable occurrence, and howto correct them. The list on the next page details thecauses and cures by number. The cures will correctthe majority of belt conveyor troubles. However,some remedies require lengthy procedures whichshould be referred to your Rexnord representatives.

SECTION VBELT CONVEYOR TROUBLE-SHOOTING GUIDE


COMMON BELT CONVEYOR COMPLAINTS

COMPLAINT

CAUSEIn Order ofProbable

Occurrence

COMPLAINT

CAUSEIn Order ofProbable

Occurrence

Belt runs off at tail pulley 7 15 14 17 21 –Excessive wear, includingrips, gouges, ruptures andtears.

12 25 17 21 8 5

Entire belt runs off at allpoints of the line.

26 17 15 21 4 16Excessive bottom coverwear.

21 14 5 19 20 22

One belt section runs off atall points of the line.

2 11 1 – – –Excessive edge wear,broken edges.

26 4 17 8 1 21

Belt runs off at head pulley. 15 22 21 16 – –Cover swells in spots orstreaks.

8 – – – – –

Belt runs to one sidethroughout entire length atspecific idlers.

15 16 21 – – – Belt hardens or cracks. 8 23 22 18 – –

Belt slip. 19 7 21 14 22 –Covers become checked orbrittle.

8 18 – – – –

Belt slip on starting. 19 7 22 10 – –Longitudinal grooving orcracking of top cover.

27 14 21 12 – –

Excessive belt stretch. 13 20 21 6 9 8Longitudinal grooving orcracking of bottom cover.

14 21 22 – – –

Belt breaks at or behindfasteners; fasteners tearloose.

2 23 13 22 20 10Fabric decay, carcasscracks, ruptures, gouges(soft spots in belt).

12 20 5 10 8 24

Vulcanized spliceseparation.

13 23 10 20 2 9 Ply separation. 13 23 11 8 3 –

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1. Belt bowed � Avoid telescoping belt rolls orstoring them in damp locations.* A new beltshould be straighten out when �broken in� or itmust be replaced.

2. Belt improperly spliced or wrong fasteners �Use correct fasteners. Retighten after runningfor a short while. If improperly spliced, removebelt splice and make a new splice.* Set upregular inspection schedule.

3. Belt speed too fast � Reduce belt speed.4. Belt strained on one side � Allow time for new

belt to �break in.� If belt does not break inproperly or is not new, remove strained sectionand splice in a new piece.*

5. Breaker strip missing or inadequate � Whenservice is lost, install belt with proper breaker strip.

6. Counterweight too heavy � Recalculateweight required and adjust counterweightaccordingly.* (If using screw take-ups reducetake-up tension to point of slip, then tightenslowly.)

7. Counterweight too light � Recalculate weightrequired and adjust counterweight accordingly.(If using screw take-up, increase tension).

8. Damage by abrasives, acid, chemicals, heat,mildew, oil � Use belt designed for specificcondition. For abrasive materials working intocuts and between plies, make spot repairs withcold patch or with Permanent Repair Patch.Seal metal fasteners or replace with vulcanizedstep splice. Enclose conveyor for protectionagainst rain, snow and sun. Don't overlubricateidlers.

9. Differential speed wrong on dual pulleys �Make necessary adjustment.*

10. Drive underbelted � Recalculate maximum belttensions and select correct belt. If conveyor isover-extended, consider using two-flight systemwith transfer point. If carcass is not rigid enoughfor load, install belt with with proper flexibilitywhen service is lost.

11. Edge worn or broken � Repair belt edge.Remove badly worn or out-of-square sectionand splice in a new piece.

12. Excessive impact of material on belt orfasteners � Use correctly designed chutes andbaffles. Make vulcanized splices. Install impactidlers. Where possible, load fines first. Where

material is trapped under skirts, adjustskirtboards to minimum clearance.*

13. Excessive tension � Recalculate and adjusttension. Use vulcanized splice withinrecommended limits.

14. Idler rolls not turning � Correct or replacestalled rolls. Lubricate. Improve maintenance.(Don�t overlubricate.)

15. Idlers or pulleys out-of-square with centerline of conveyor � Realign. Install limitswitches for greater safety.

16. Idlers improperly placed � Relocate idlers orinsert additional idlers spaced to support belt.*

17. Improper loading, spillage � Feed should bein direction of belt travel and at belt speed,centered on the belt. Control flow with feeders,chutes and skirtboards.

18. Improper storage or handling � Refer toyour Rexnord representative for storage andhandling tips.

19. Insufficient traction between belt and pulley� Increase wrap with snub pulleys. Lag drivepulley. In wet conditions, use grooved lagging.Install correct cleaning devices on belt. Installcentrifugal switch for safety.

20. Material between belt and pulley � Useskirtboards properly. Remove accumulation.Improve maintenance.

21. Material build-up � Remove accumulation.Install cleaning devices, scrapers and inverted�V� decking.* Improve housekeeping.

22. Pulley lagging worn � Replace worn pulleylagging. Use grooved lagging for wet conditions.

23. Pulleys too small � Use larger diameterpulleys.

24. Radius of convex vertical curve too small �Increase radius by vertical realignment of idlersto prevent excessive edge tension.

25. Relative loading velocity too high or too low� Adjust chutes or correct belt speed. Consideruse of impact idlers.

26. Side loading � Load in direction of belt travel, incenter of conveyor.

27. Skirts improperly placed � Install skirtboardsso that they do not rub against belt.


* Consult your Rexnord representative for additional recommendations or procedures. Space limitation prevent us from printing completeinformation in this guide.

CAUSES AND THEIR CURES

Impact IdlersPrevent damage to the belt at the loading point.These idlers may be troughing or flat types withgrooved, molded rubber rolls. It is standard practiceto use impact idlers at all loading and transfer pointswhen the impact exceed 40 foot pounds

Return IdlersSupport the empty belt between the discharge pointand the tail pulley.

a. Standard � Used where materials are not sticky,corrosive or abrasive.

Ceramic or urethane covered rolls alsoavailable.

b. Spiral � Used where sticky materials adhere tothe belt where a corrosive environment ispresent or abrasive wear is a problem. Theirunique construction minimizes belt fleet anddamage to the return belt due to material build-up on the idler rolls. Spiral roll idlers can be usedfor belt travel in one direction only.

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Carrying Idlers(Troughing or Flat)Support the belt in the section of the conveyor thattransports the material. These idlers may be flat ortroughed to shape the belt to prevent spillage andare available in 20°, 35° and 45° trough angels withequal or unequal roll lengths.

Ceramic or urethane covered rolls also available.

SECTION VIIDLER REPLACEMENT PARTS IDENTIFICATION


TYPES OF IDLERS

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c. Rubber disc � Used under the same conditionsas the spiral idler. These idlers can be used forbelt travel in either direction. Massed end discsare standard.

Urethane and ceramic disc rolls also available.

Carrying Belt Training Idlers(Troughing or Flat)

Assist in keeping the belt centered on the conveyor.Actuating shoe type is used on belt traveling ineither direction. Positive type is used on belttraveling in one direction only and is illustrated.


Return Belt Training Idlers

Used for the same purpose as are Carrying TrainingIdlers. They are of the actuating shoe type, belttravel � either direction, and the positive andinclined pivot types, belt travel � one direction only.The positive arm type is illustrated.



TYPES OF IDLERS, (cont)

Troughing Impact

Idler Styles

Troughing Training

Ribbed Covered Return Disc Return Spiral Return

Flat Impact Live Shaft Impact Inclined Return Training

Rexnord Corporation, Idler Division4800 West Mitchell Street, P.O. Box 2022Milwaukee, Wisconsin 53201(414) 643-3000 Fax: (414) 643-2600www.rexnord.com e-mail:[email protected]

Bulletin No. 6000 © Copyright Rexnord Corporation 2002 11/05 500 - RAM Printed in the U.S.A.

field service manual - rexnord

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