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Installation, Maintenanceand Troubleshooting GuidePower Transmission Belt Drives

CONTENTSINSTALLATION 1 20

V b e l t s 1 1 1Poly-V Bel ts 12. 15P o s ~ t ~ v er ~ v e e lt s 1 6 - 1 8Var~ ab l e peed Be l ts 19 -20

MAINTENANCE . . . . . . . . . . . . . . . . . . . . 2 1 - 2 4What To Look For . . . . . . . . . . . . . . . . . . . 2 1 - 2 3What To Listen For . . . . . . . . . . . . . . . . . . . . 2 4

TROUBLESHOOTING . . . . . . . . . . . . . . . . 2 5 - 2 7V-bel t Pe r formance Analys is . . . . . . . . . . . . 2 5 - 2 6Troubleshoot ing Char t . . . . . . . . . 2 7

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INSTALLATIONV-BELTS

To rqu e- Flex$ Hy-T: Compassw-V -Stee l,H y -TSWedge,Torqu e-Te am $ Hex and F.H.P. V- belts

1.INSPECT SHEAVESWorn sheaves will substantially reduce belt I l fe. I f thegrooves are worh, the be l t will bo t tom ou t . Th ls will resu l t In s l lppage and the be l t s may char o r bu rn . I f thes~dewa l ls re d lshed ou t , the bo t tom shou lder o f thesheave w ~ l l ea r the bo t tom corner o f the be l t , thuscaus ing p rematu re fa l lu re .

Fig. 1

C h e c k s he a v e s f o r r u s t a n d w e a r . W ~ p e l e a n o f 01 1a n d g r e as e .

LIKE THlS NOT THlS

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Industry Standard Groove Dimensions for V-belt SheavesS R O O V E F I L E B R E A K A L L. A N G L E , - S H A R P C O R N E R S

k b n 4

Standard Groove Dimensions

Face Width of Standardand Deep Groove Sheaves

Face Width = S,(N,-1) + 2SeWhere :

N, = Num ber o f G rooves

Industry Standard Groove Dimensions for Hy -T Wedge Belt SheavesF l L E B R E AK- ALL S H A R P Face Width of StandardG R O O V E , C O R N E R S 1 -

90 ' r O"30' and Deep Groove Sheaves'- - -4

hg- L Face Width = Sg(Ng-1) + 2Se

Where :

GrooveAngle* &20'343 834383436383436383638

Standard Groove Dimensionsitch DiameterI

CrossSection

A

e

C

D

E

ainches

,125

,175

**Sg.031inches

0.625

0.750

1.000

1.438

1.750

*b ginchesMin.Recom-mendedinches3. 0

-5. 4

9. 0

13.0

21.0

seinches

+.0700.375 -.ooo+.I500.500 -.ooo+.I50. 0 . 6 8 8 . 0 0 0

+.2500.875 -,ooo+.2501.125 -.ooo

hg;031inchesRangeinches2.6 to 5.4Over 5.44.6 to 7.0Over 7.07.0 to 7.998.0 to 12.0Over 12.0

12.0 to 12.9913.0 to 17.0Over 17.018.0 to 24.0Ove r 24.0

,87913 8 7 -+ 007.895j1.25911.271 -t ,0071.2831

. 4 94 + ,005 0.490

A504 -'637 ( + 005,650:-0.780

0.580

1.050

1.300

,300

.400

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2.MOUNTING SHEAVES

THE QD HUBConvent iona l Moun tThe Conventional Mount ing pos i t ion fo r a l l "QD"Sheaves 1s with th e Hu b flange located toward th ebear ing. Loosely assemble the QD Hub in the r im in-ser t the pu l l -u p bol ts ( f inger t ight) . S l ip the looselyassembled uni t , f langed end f i rs t , and al ign i t in thedes i red p os i t~ on n the shaf t.T ighten the hol low head setscrew in the f lange downon the key only snug enough to keep i t in th e des iredpos i t ion on the shaf t .T ighten each p ul l -u p bol t a l ternately and evenly .F inal ly , t ighten the setscrew dow n t ight on the keyto h old i t securely in p lace when dr iv ing . Conventional mount

RemovalP lace two or th ree o f the pu l l -up bo l ts in the tappedholes in the sheave. As you draw up on the bol ts theyact as jack screws against f lange of QD h ub to b reakthe cone gr lp between hub and r im .

Easy off

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THE SPLIT TAPER BUSHING- How To Moun t Split Taper Bushing Sheaves

start capscrews dr ~v e long edge of both sheaves furn ~sh ed lth bush~ng s.

How To R emove Split Taper Bushing Sheaves

1 Remove capscrews 2 Put two capscrews ~npush-off holes 3 Remove sheave fro m shaft.In f lange T~ghten n t ~ lheave has

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THE TAPER-LOCK@BUSHING

MOUN'l7NGInsert bushing in hub. Match holes (not threads)and slip entire unit ont o shaft. Put screws in to theholes that are threaded in hub only. Align theproduct and tight en screws. As bushing is wedgedinward it contracts-evenly-and grips the sha ft .

REMOVALTake the screws out entirely. Insert one of theminto the hole which is threaded in the bushing.Use as jack-screw. This disengages the bushing.Its grip is "unlocked," permi ttin g quick, easy re-moval of product w ~ t h o shock to bearings ormachinery.

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3.CHECKING ALIGNMENTb

4. SELECTING BELTS

.-I-. essential t o m a ~ n t a l nong V-belt- .: + e

NOT THlS WAY!THlS WAY

I)* Fig. 3

S t r a ~ g h te d g e t o u c h ~ n gsheaves a tf o ur p o ~ n t s n d ~ c a t e sl ~ g n r n e n t

Fig. 4

Belt T.W.

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5.MATCHING OF BELTS

All be lts sholDon't Mix Belt Brands

~ l dave the same !eng th code number,Don't Mix New and Used Belts

Nefl Old

Old

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6. INSTALLING BELTS

WRO NG RIGHTNever force the belts into a sheave with a screwdriver Always move the dr ~v er nit forward so the b elts cano r wedge because you w ~ l lupture the envelope fab- eas~ly be sl~pp ed nto the sheave grooves withoutr c and break the cords. damage to the belts.

Center Distance Allowances for Belt Installation and Take-UpA f te r c a l c u l a t in g th e c e n te r d ~ s t a n c e a s ed o n t h e s t an d a rd p ~ t c heng tho f t he be l t , make su re t ha t t he cen te r d i s t ance can be moved c lose r t o -g e th e r b y t h e m i n i m u m ~ n s t a l l a t ~ o nl l owance f i gu re shown in Tab le 3 t oI n s u re t h e b e l t s c a n b e i n s t a l l e d w ~ t h o u t a m a g e . T h e c e n t e r d i s t a nc es h o u l d a l so b e a d j u st a b l e t o a l l o w f o r t h e m i n i m u m t a k e . u p a l l o w an c es h o w n i n t h e l a s t c o l u m n o f T a b l e 3 t o a l l o w f o r m a n u f a c t u r i n g to l e r a nc e

Table 3 and be l t s t re t ch .Minimum Allowance Below Standard Mlnimum Allowance Above

5r.nd.rd Center Distance for Installotian of Belts Standard Center Distance Shorter C e n t e r Dlstance fo r V -b e l t Instal lat ionLength' for Maintaining TensionDestgnat8on Ilncher)

i m 7e.m I l omAl l Sect~onr

I TWrn ,.om: 5 .a 38 075 I20 100 150 1 00- 2 o 60 0 75 1 20 100 150 150 2 00 1 501 5: 'a 90 075 1 30 1 25 1 60 1 50 2.00 2 00

II i0.0120 100 130 1.25 160 150 200 2 50/'2310158 100 150 1.25 180 150 210 200 210 3 008 158.0195 1 125 180 2.00 2 20 2 00 3 00 2 50 3 40 3 50'95o 240 { 1 50 1 90 2 00 2 0 2 00 3 20 2 50 3 502AO o 270 200 200 2 5 0 250 320 25 0, 60 4 50270 o 330 1 : 220 ,200 250 250 3501 3002 5 00 1 Longer C e n t e r Dlstance fo r V - b e l t Take-Up330 o 420A20 an d aver

Table 4- y-T Wedge V-belts

StandardLength

Designation

- I n e a c h group the range IS to, bu t no t ~ n c l u d ~ n g ,he second length.A l l d ~ m e n s ~ o n sn Inches.

2 002 50

2 702 90

--

Minimum AllowanceAbove StandardCenter DistanceFor Mainta iningTension, Inches

Al l Cross Sections

Minimum Allowance Below StandardCenter Distance For InstallationOf Belts, Inches

3V

2 503 0

3VTorque-Team

6 001 5% af be l t length

3 604 10

5V

3 00 4 003 50 ; 4 40

5VTorque-Team

8V 8VTorque-Team

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7. TENSIONING BELTS

Ch e ck th e te n s io n o n a n e w ly ~n s ta l l e d -b e l t d r i ve

General Common Sense Rules of Tensioning:a . Ideal tens ion is the lowest tens ion at which the bel tw i l l not s l ip u nder peak load condi t ions.b. Check tension f r equen t l y dur i ng the f i rs t 2 4 - 48

hours o f r un - i n opera ti on .c. Over tens ion ing shor tens bel t and b ear ing l i fed. Keep bel ts f ree f rom fore ign mater ia l which maycause s l ip .e. Make V-dr ive inspect ion on a per iod ic bas is. Ten-s ion when s l ipp in g.f . Mainta in sheave a l ignment whi le tens ioning thedr ive. (See p ic ture, page 10. )I f you want to check the tens ion in a convent ional V-bel t dr ive, use the procedure below:a. Measure the span l eng th , t .Table 5- elt Deflection Force (Pounds)Based on opera t i ng speeds o f 10 00 -30 00 fee t perminute . For bel t speeds In excess of 3 00 0 feet per

A t e n s ~ o ne s te r IS a q u lck a n d co n ve n ie n t me a n s o festablishing t e n s io n in g va lu e

b. At the center of the span ( t ) apply a force (per -pend i cu la r to the span) l a rge enough t o de f l ec t thebel t 1/64'' for every in ch of span length . For example ,the de f l ec ti on o f a 10 0 i nch span wou ld be 10%4 o rinches.c. Compare the force you have appl ied w i th the valuesgiven in Tables 5 and 6. I f the force is between thevalues for norma l tens ion and 11/2 t ime s norm altens ion, the dr ive tens ion should be sat is fac tory . Aforce below the value for normal tens ion ind icatesan under tens ioned dr ive. I f the force exceeds thevalue for 11/2 t imes norma l tens ion , the d r i ve i st i gh te r than i t needs to be . A new dr i ve can be t i gh t -ened i n i t i a l ly to two t imes norma l tens ion t o a l l owf o r t h e n o r m a l d r o p i n t e n si o n d u r i n g r u n - i n .

minute , reduce th e de f lec t ion forces by 20, . (Checkfac tory for operat ing speeds less than 1000 F.P.M.)

CrossSectionAAABB

TORQUE-FLEX

Smal lDiameterR ange3.0- 3.63 .8 - 4 .85.0- 7.03.4- 4.24.4- 5.6

PoundsForce ForNormalHorsepower

5 .05 . 96. 77. 17.7

B

PoundsForce For1% TimesN ormalH orsepow er

7 . 08. 49. 6

10 .111 .0

CVS

5.8- 8.6

HY-TPounds

Force ForN ormalH orsepow er3. 23 . 84 . 44. 65 . 8

PoundsForce ForNormalHorsepower

3. 64.35. 04.96. 5

PoundsForce For1% Ti mesN ormalHorsepower

4. 55.26. 06. 18 . 0

7. 1

PoundsForce For1% Ti mesNormalHorsepower

5. 26.27 . 26. 99. 3

8. 210.0 9 . 6 13 .8

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7. TENSIONING BELTS (Cont.]Torque-Team Belt Tensioning

A mu lt iple gauge tensioning device is recommended toestablish the prope r tension on Torque-Team'be lts.

Double-che ck sheaves with steel stra ight edge forproper al ignment after tensioning the dr ive.

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8. BELT GUARDSG u a r d s f o r d r i v e s i n s u r e s a f e t y a n d c l e a n l i n e s s .Screened, meshed or gr i l led be l t guards are the mostsatisfactory because they al low air to circulate andheat to escape.

9. IDLERS

Genera lAvoid The Use Of ld lerIf Possible

A proper ly designed m ul t ip le V-be l t dr ive wi l l not re-qu i re an id ler to de l iver fu l ly ra ted horsepower i f p rop-er tension can be mainta ined. Id lers a lways put anaddi t iona l bending stress po in t on the be l t which re-duces the belt horsepower rat ing and reduces belt l i fe.The smal ler the id ler , the greater the reduct ion in be l tl i fe due to the increased bending stresses.Ins ide ld lerA V-grooved id ler located on the ins ide o f the be l ts on

Back Side ld ler4A back side idler increases the arc of con tact on b othsheaves, however, i t forces a backward bend in th eV-bel t that contr ibutes to premature fa i lu re . The id ler

puts addi t iona l s t resses in the bo t tom por t ion o f thebel t which wi l l resu l t i n bot tom cracking. I f a back s ideid ler is used, the d iameter o f the f la t id ler pu l leyshould be a t least t ime s the d iameter o f the smal lsheave and loca ted as close as possible to the s mal lsheave.

- DRIVEN

DRIVER

Kiss ld lerA kiss id ler d i f fers f rom th e back s ide id ler because i tdoes not penetra te the be l t span creat ing a back bend 'on the be l t and consequent ly does not contr ibute topremature fa i lu re o f the be l t .

The useage of k iss id lers is not to o comm on, how-ever i t p rovides a method of con tro l l ing be l t v ibra t ionand whip on shock and pu lsat ing load dr ives. The k issidler could be used in single belt dr ives where joinedbelts are not appl icable.I f a k iss id ler is used, the d iam eter o f the f la t pu l leyshould be at least 1y2 t imes the d iamete r of the sma l lsheave.

DRIVER

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POLY-V'?BELTS1. INSPECT SHEAVES* Worn sheaves can reduce be lt l i fe substant ial ly. I f thegrooves are worn, the sheave points wi l l cut the belt .I f the side wal ls are "dished out," s l ippage may resultand bu rn the be l t.

Fig. 8Check sheaves for rust and wear. Wipe clean ofoi l an d grease. Check sheave groove with Poly-V groove gauge.

Table 7Industry Poly-V Sheave Groove Dimensions and Tolerances

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2. MOUNTING SHEAVES 3.CHECKING ALIGNMEN TPoly-V be l t sheaves are insta l led and remove d in the Proper a l ignment i s mo re cr i t i ca l fo r Po ly-V sheavessame man ner as convent iona l V-be l t sheaves. Fo l low than fo r convent iona l V-be l t d r i ves. Basica l l y , the

#the sam e procedures as out l ined on pages 3 , 4 a nd 5 a l~ gnm en t heck i ng p rocedu res fo r Po l y-V be l t s a re -i n t h i s m anua l and as recommended by the sheave the same as fo r V -be l t s wh i ch a re ou t l ~ ne d n page 6manu fac tu re r . o f t h i s manua l .

4. SELECTING BELTS

Fig. 10Belt gauge

Select be l ts to matc h sheave as rn the example above:"1-" sect ion sheave gauge f i ts pul ley, so use "L " bel ts.

SIZE NOMENCLATUREBELT

6 7 5 L 6

6 7 . 5 i n ch " L" 6Pitch Length Section Ribs

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5. ATCHING BELTS 6. INSTALLING BELTS

' . I - = l ea ve o n e s h e a v e g r o o v e o pe n t o e l l m ~ n a t e- - i 5 3 1 e ~ n t e r e f e r e n c e e t w e e n b e l ts .

','atching' ' - :c ' lng I S not requi red fo r mo st Poly-V bel t dr ives .- : ;.ever, i f you have a special ap pl ica t ion where-3 t ch ing i s r equ i red , speci fy "matched be l t s" on the:~ : j e r and a l low su f f~c ien t ead t ime. Match ing code. m b e r s w i ll n o t a pp e ar o n th e b e l ts .

WR O N GN e v e r f o r ce t h e b e l t s o n t o a sh e a ve w ~ t h s c re wd r ,v e r or u e d g e b e ca u se y o u w ~ l l u p t u r e t h e f a b -r c ar7d break the cords .

R IG H TA lw a ys m o v e t h e d r ~ v e r n i t f o r w a rd s o t h e b e l t sc a n e a s ~ l y e s l ~ p p e dn t o t h e s he a ve g r o o ve s w ~ t h -o u t d a m a ge t o t h e b e l ts .

Table 7- oly-V Belt Recom mended Installation and Take -Up AllowancesStandard Effective Length,

I Inches

1 U p To a n d Incl. 20.0Ov e r 20.0 o a n d incl. 40.6Ov e r 40.0 o a n d I n c 60.0

Minimum Allowance AboveStandard Center Distance forMain taining Tension, inchesAll Cross Sections

0.30.50.7

Minimum Allowance Below Standard Center Distancefo r

J

0.40.53.6

Installation of Belts,L

C.9

inchesM

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7. TENSIONING BELTS

Installation TensioningHy-T Poly-V drives w, ll be properly tensioned i f the de -f lect ion force "F " is appl ied mid-way between thebel t 's tangent p oints wi th the pul ley , as shown in F ig.11 , and is used to def lec t the bel t . The def lec t ionshould be equal to .015" per inch of unsupp orted be ltspan. The force "F " should be the value shown in thefol lowing table.To improve tens io ning accuracy, the dr ive shouldbe run brief ly to properly seat the belt . At least onesheave should be f reely ro tat ing du r ing the tens ioningprocedure.

A tension tester is a quick and convenient means ofes tab l ish ing tens iona l va lue . Refer t o p a g H 0 ens ion-ing of Torque-Team bel ts for procedure and i l lus t ra-t ion of te nsio ning devices.

Table 8- elt Deflection Force

Table 9MINIMUM RECOMMENDED SMALL SHEAVE DIAMETERS

Force "F"Ibs. per rib0.40.50. 61.72 .12.56.47.78 .8

I BeltCross SectionJJJLLLMIIW

FOR ELECTRICMotorNameplateHorsepower

.12 or less

.25

.33

.50

.751

1.52357.5

1015202530

40506075

100

12 515020025030 0

Small SheaveDiameter Range1.32 - .671.77 - .2 02.36 - .9 52.95 - .7 43.94 - .9 25.20 - .697.09 - .829.29 - 1.81

12.40- 5.75

MOTORS (FOR POLY-V & V-BELT DRIVES)STANDARD MOTOR R.P.M.

3450 1750

1.251.251.502.002.252.25

2.252.502.502.503.00

3.003.754.504.50

1160Small

1.251.251.502.002.252.25

2.502.502.503.003.00

3.754.504.504.505.25

6.007.007.639.00

10.00

11.00

57570Sheave

1.501.502.002.502.502.50

2.502.503.003.003.75

4.504.505.256.006.75

6.758.389.00

10.0013.00

13.0013.00

67 5Diameters-Inches

3.003.00

3.003.003.003.754.50

4.505.256.006.756.75

8.259.00

10.0010.0013.00

15.0018.0022.00

3.003.00

3.003.00

3 . 0 0 3 , m3.003.754.504.50

5.256.006.758.259.00

10.0010.0011.0013.0015.00

18.0020.0022.0022.0027.00

3.754 . 5 04 . 95 2 5

6 @ :6 ; s8 . 2 59 .W

10 DC,

10.0011.0012.0014.0018.00

20.0022.0022.0022.0027.00

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POSITIVE DRIVE1. INSPECT PULLEYS

Check pul leys for rus t and wear and w ipe c lean of o i i and grease.Typical Positive Drive Pulley Groove Profiles

Worn Outside ~iameter1 i g . 2 L orrect FitBelt Bottoms

Table 10R b

1 /64 max.1 /64 max.%2 max.

StockB el tPi tches

1 15 ( X U

R t+.002.015-.ooo+.002~ 0 2 5 - . ~ ~ ~+.005. 0 3 0 - . ~ ~ ~+.005

Approx.Pi tch,187,200,234

B el tToothProfile

FHD

T h k+.ooo.060-.002+. 00.065-.003+.OOO. 0 7 3 - , ~ ~ 4+. 00

BW+.002~068-.ooo+.002. 0 5 2 - , ~ ~ ~+.003. 0 8 0 - . ~ ~ ~

120+.004

40 " + 3"50 " + 3"40 " + 3"

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1.TYPE PULLEYSVarious types of pul leys are used on Posl t lve Dr iveBel t dr ives . The type furn ished- poke, web, etc .-i s governed by the number of grooves and the pul leyman ufacture r 's preference. General ly pul leys of smal ld i ameter do no t use bush ings bu t a re o f the i n tegra lhu b type. The larger pul leys are genera l ly used w i thbushings. The bas ic types of Pos i t i ve Dr ive Bel t pu lleys are shown below and are typ ica l o f the w ide va r l -e ty used. The min imum recommended pul ley d larne-ters are shown in Table 11.

Plast ic pul leys are only recommende d for l ight du tyappl icat ions.

FOR USE WITH BUSH INGS WITH INTEGRAL HU B

- W - E 7 r - W -r - i- i. -+-& i c b

n ~+3 - -

TYPE AF TYPE CF TYPE DFFig. 13

Table 11Minimum Pulley Diameters

Recommended Minimum *Pitch I S ~ e e d D ~ Pitch Diam. in. I No. of Grooves

I ( XH ) 1 1160 1 .6.685 / ?4XR 1

3/ s in .11603500

3.CHECKING ALIGNMENT

,6371.913

The proper al ignment of Posi t ive Dr ive pul leys is morecr i t i ca l than for conve nt ional V-bel t dr ives . Esse nt~al lyhowever , the a l ignment check ing procedure is the ,same as for V-bel ts as deta i led on page 6 of th ismanua l .Determine Direction Of Side TravelStock or s tandard Pos i ti ve Dr ive bel ts will r ide towardthe le f t f lange. I f on ly one f lange is used, i t should beplaced on the le f t . I f a dr ive requi res that th e bel t r idetoward the r igh t f lange, "specra l o rder " the bel ts inmandre l quan t i t ies f r om the m anufac tu re r .

lG X L-16 L

DETERMINE DIRECTION OF SI DE TRAVELn

Fig. 14

USE OF THE RIGHT-HAND RULE

4. SELECTING BELTSSIZE NO MENCLATURE

BELT

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5. MATCHING BELTS

Match ing is not requ i red for most Posi t ive Dr ive be l tdr ives. However, i f you have a special appl icationwhere match in g is requ ired, speci fy "matched be l ts"on the order and a l low suf f ic ient lead t ime. Mat ch ingcode numbers wi l l not appear on the belts. Two belts2 inches wide wi l l operate sat is factor i ly on a 4- inchwide pul ley.6. INSTALLING BELTSThe be l t should never be forced or pr ied over th e pu l -ley f lange dur i ng instal lat ion. R eduction of center dis-tance or i d le r ten s~ on i ll pe rmi t the be l t to s l ide on tothe pu l ley easily. Otherwise, one or bo th pul leys should

- be removed.To assure smooth operat ion and prevent prem aturefa~ lure, e l ts in storage should be protected againstsharp b ending or creasing. They should not be subject-ed to extreme heat , low temperatu re or h igh hum id i ty .7. TENSIONING BELTSPoslt lve Dr ive be l ts should be insta l led wl th a s nug f i t .The snug f i t will provid e longer bel t l i fe, less wear onb e a r ~ n g sand qu ie ter operat ion. The be l t 's posl t ivegr ip e l iminates the need for h igh in i t ia l tension ingTable 12- able of Values

which cou ld cause premature be l t fa i lu re . A be l t ine i ther the XH or XXH p i tch can be insta l led wi th someslack becauseof th e deepe r tooth sect ion un less shockloads or reversals are abnorm al ly high.If the torque is unusual ly high, a loose belt may" jum p teeth" du r ing star tup. I f th is condi t ion occurs,gradual ly increase the tension unt i l th e be l t operatessat is factor i ly . A good ru le o f thumb is to insta l l thebel t under o f the a l lowable work ing tension shownon page 6 0 of th e Goodyear Posit ive Drive engineeringdesign manual . The precise tension can be determinedby using the method shown be low.Tension ing MethodThe procedure to proper ly tension a Posi t ive Dr ivebelt is as follows:1. Apply a force a t the midpo in t o f the span between

the two pu l leys. Deflect the be l t 1/64" fo r each inchof span length.

2. Insta l la t ion tension should be regula ted so that th eva lue o f th is app l ied force equals the va lue o f fg iven in the fo l l ow ing fc rmu la :f = T + (s /L) K1 6

where s = th e span d istance in inches.T = the tension in pounds found inthe Table .K = the cons tan t f rom the Tab le .L = the length o f the be l t .

d is tob e 1/64of t h e valueof si n ~ n c h e s .

3. I f the d ef lect ing force is less than that g iven in theformula, t he be l t is too loose. I f the def lect ing forceis greater than that g iven in the formula th e be l t istoo t i gh t .

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VARIABLE SPEED DRIVES 1. INSPECT SHEAVESTypes of Variable Speed Drives

Variable To Fixed Sheave

Both Sheaves Variable

The condi t ion of the sheaves should be checked be-fore a new set o f var iab le speed bel ts are ins ta l led.Di r ty or ru s ty sheaves im pai r th e dr ive 's e f f i c iency andabrade the cover o f the be l t wh i ch resu lt s i n p roma tu refa i lure. Remove any rus t a nd wipe sheaves c lean ofo i l an d grease.

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2. ALIGNING SHEAVESTypical Variable Speed Drive

WRONG-Check fo r misalignmentan d offset distance "D "

--Fig. 16 u

I wD2

Fig. 17Note belt misalignment in Fig. 16. To correct move one sheave so thatthe straight edge (Fig. 17) I S equ id~st ant rom both sides of the narrowsheave and so that the belt edge is equidistant from the straight edge.

3.SELECTING BELTSRefe r t o manu fac tu re r ' s recommenda t i ons . The be l tlength on f ixed cen ter dr i ves wi th both pu l leys var iab lei s c r ! t i c a l a nd a f fe c t s d r ~ v e p e e d v a r i a t i o n s . B e l t!ength wi th one varrab le and one f i xed pu l ley i s on lycr l t i ca l as it pe r ta ~ns o a l l owab le i nc rease and de -crease in center d is tances.4. INSTALLING BELTSSpecial care shou ld be taken when ins ta l l i n g var iab lespeed be l ts so that t he be l ts and sheaves are not da m-aged . Theva r i a to rzsheavesmay have to be fu l l y openedto fac i l i t a te i ns ta l l a ti on . The d r ive cen te r d i s tance maya lso have to b e shor tened to a l low for insta l la t ion . Oneor bo th sheaves may have to be removed . A f te r as -

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MAINTENANCEV-be lt dr ives are recognized as an extreme ly rel iable tools. The main ingredients of good maintenance areand eff icient means of power transmiss ion. Since they to l ook and l i s ten and then to cor rec t apparen t d r~ v eare basica l ly t roub le- f re e, they are o f ten ignored and prob lems.do not receive the m in im al a t tent ion requi red to rea l ize The fo l lowing maintenance and t roub le shoot ing 'ethe i r fu l l benef i t and l ife . po in ters provide in format i .on to he lp you estab l ish anV-bel t dr ive maintenance is not compl icated, nor ef fect ive V-be l t dr ive maintenance program .does i t requ i re a great dea l o f t im e or a large var ie ty o f

Look and Listen

Following installation of V-belts, inspect the driveand watch it while it runs.

WHAT TO LOOK FOR:

Inspection of a V-belt drive is simpl y a mat ter oflooking and listening. (r

1. OIL AND GREASEBelts exposed to oil in spray, liquid or paste formfail prematurely. A drive should be well "policed."Leaky bearings should be repaired immediately.Excess oil on a bearing will splash on the belts. Ifthese conditions cannot be corrected special oil-resistant belts should be used.Too little oil wil l cause bearing failure which, i nmany cases, is blamed on the belts. This condi-

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2. DIRTNo equipment operates best when i t is d i r ty and be l tsare no exception. Dir t accelerates belt wear and dir tbu i ldup in a sheave groove imp ai rs t ract ion.

b-

Remove Di r t

5. CRACKINGBottom cra cking wi l l not reduce the tensi le st rengthor the operat ing e f f ic iency o f th e be l t . H igh tempera-tures, sm al l d iameter pu l leys and dust w i l l acce leratebot tom cracks. Bot tom cracking can be reduced byusing larger sheaves and larger reverse bend idlersheaves. I t is not necessary to replace a belt sim plybecause bo tto m crackin g has been observed.

3. ADDED LOADS 6. BELT DRESSINGAdded loads shorten belt l i fe. A check should be m adeto see that no addit ional loads have been added sinceth e or iginal dr ive was selected. Take note of the dr iv esystem shown In the fo l lowing i l lustra t ion.

This added loadm ~ g h teducemotor be l t l i fet o 18 months

overloaded now

Do no t use be l t d ress i ngo f a ny k ~ n d .

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11. CHANGE IN RIDE OUT.VIBRATION

P re ve nt b e lt w h ~ p p ~ n g

8.TENSIONA d ju s t t e n s ~ o no va lues show n in t ab les 5 & 6, page 9o r t a b l e 8, page 15.9. HEAT

C h an g e In r ~ d e u t ~ n d ~ c a t e sn e v e n b e l t w e a r o r w o r n s h e av e s

12. LATERIAL VIBRATION

13.BELT WEAR

Al l be l t s a re cu red I n a sc~en t i f i ca l l y on t ro l l ed t imeand t empera tu re p rocess . Be l t s opera t ing I n t emp er -a tu res o f l ess t ha n 140'F. are no t ma te r ia l l y a f f ec ted ;h o w ev e r, a t h ~ g h e r e m p e r a t u r e s o v e r c u r i n g t a ke sp lace and shor t ens be l t l i f e . Be l t s opera t ing I n t em -pera tu res above 140-F. shou ld be checked f requen t l yand a spec ia l hea t - res i s t an t cons t ruc t i on shou ld becons idere d i f be l t l i fe is not sat is fac tory . W ear o n s ~ d e w al l s n d ~ c a t e so n s ta n t s l ~ p p a g e , xc es

s lve dus t , o r r ough sheaves .10.BELT TURN OVER 14. FOREIGN MATTER

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TROUBLESHOOTING -V-BELT PERFORMANCE ANALYSIS

Cause of Fai lure - xcessive exposure to oi l or grease has Cause of Fai lure - eather ing or "c raz ing" caused by thecaused the be l t to swel l, become sof t and the bot to m enve lope e lements and aggravated by sma l l sheaves.seam to "open up. " Correc t ion- rov ide pro tec t ion for the dr ive and rep lace be l tCorrec t ion - rov ide sp lash guards, do not over lubr ica te , or belts.c lean belts and sheaves with gasol ine.

Cause of Fai lure- ut bot tom and s idewall ind ica te be l t was Cause o f Fa i lure - pin burn caused by a f rozen or lockedpr ied over sheave and dam aged dur in g ins ta l la t ion . dr iven sheave.Correc t ion - e sure to use proper length be l t and move Correc t ion- e te rm ine tha t t h e d r i ve componen ts t u rh f r ee lytens ion ing a l l the way " in" when ins ta l l ing be l t. and t ighten belt , i f necessary.

Cause of Fai lure - onstant s l ippage caused by insuff ic ient Cause of Fai lure - ough sheave sidewal ls cause the covertens ion in be l t . to wear o f f in an uneven pat tern .Correc t ion - ens ion dr ive in accordance wi th equ ipment Correc tion-F ile or mach ine ou t the rough spot on th e sheavemanufacturers and th is manua l 's recomm endat ions. groove. I f beyond repa i r, rep lace the sheave.

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Cause of Fai lure - ens i le breaks can b e caused by h igh Cause of Fai lure- ack o f the be l t has been rub b ing on ashock loads, fo re ign ob jec t between the bo t tom of th e sheave bel t guard o r o ther appur tenance.and the b o t tom o f t he be l t o r damage du r i ng i ns ta l la t i on .Correc t ion- ain ta in proper dr ive tens ion and ins ta l la t ion co r rec t i on - rovide adequate clearance between belt andprocedures. Prov ide guard to keep fore ign mater ia l f rom guard o r any appur tenances.com ing in contac t w i th the dr ive .

Cause of Fai lure-Excessive dus t and rough sheaves com bine Cause of Fai lure - orn sheave grooves al lows the joinedto cause severe enve lope wear an d ear ly be l t fa i lu re . be l t t o r i de too l ow cu t t i ng th ru t o t he top band.Correc t ion - a in ta ~n heave cond i ti on , a l i gnmen t and a t - Correc t ion- eplace sheaves and m ain ta in proper be l t ten-L tem pt to pro tec t dr ive f rom excess ive dust exposure. s ion and sheave a l ignment .icL

Cause of Fai lure - lange wear on PD synchronomous be l t .Correct ion - djus t and main ta in proper pu l ley a l ignment . Cause o f Fa i lu re -We b fabr ic wear caused by improper be l tand pu l ley f it .Correc t ion- heck be l t /pu l ley f i t and rep lace worn or out -of-spec pul leys.

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