ManyRomlair beltdriven fansare furnishedwith
variable-pitchmotor sheaves. Onsome ofthese fans
sheavesmay beadjusted forlower fanspeeds without
concernof over-loadingmotors. When adjusting
sheavestoincrease fanspeed,check motorcurrentto
besuremotor isnot overloaded. Keepmotor current
withinnameplate andservice factorratings.
The sheaves used are the VL,VM, and the VPType.
Thesesheaves areeasilyadjusted andcome in
variousstyles dependingupon thesize driveand motor
shaft.
The following steps should be taken to adjust the
pitchdiameter:
1. Release the belt tension and remove belt or belts
fromthesheave.
ADJUSTINGVARIABLEPITCHSHEAVES
2. Loosen the set screw and remove key holding
adjustablehalf ofthegroove.
3. Screwadjustablehalf ofsheave outfora smaller
pitchdiameter (decreasedspeed),orinfor alarger
pitchdiameter (increasedspeed). Eachone-halfturn
will change the pitch diameter one tenth of an inch.
Adjusttwo-groove sheavesthe sameamount oneach
groove. 4LorAbelts will operate satisfactory with the
sheavefullyclosed toa maximumof fivefullturns
open. 5L or B belts will operate satisfactory with the
sheave one full turn open to a maximum of six full
turnsopen.
4. Replace the key and tighten set-screw to lock
sheave half in position.
5. Replace the belts and tighten to proper tension.
INSTALLATIONINSTRUCTIONS FORPROPELERSEQUIPPED
WITH BROWNING MALLEABLE IRON SPLIT TAPER BUSHING
Romlaircast aluminum andsteelfabricated propellers
arefurnished withsplittaper bushingsfor mountingthe
propellertothe shaft.When properlyassembled, the
bushings grip the hub with a positive clamping action.
A. Bushingbarrrel andbore ofpropeller aretapered-
this assures concentric mounting and a true running
propeller.
B. Capscrews, when tightened, lock bushing in
propeller.Use platedcap-screws threadedfull length.
-NIHSUB G.ON .AIDHTGNEL EUQROT .SBL.TF
H1-P 2-P 2-Q 2-R
02-4/1 81-61/5 81-61/5 61-8/3 61-8/3
"4/1-1 "2/1-1 "4/3-1 "2/1-
2"3
2/1-7 31314242
C. Bushing is split so that when the locking
capscrewsforcethe bushinginto thetapered bore,the
bushing grips the shaft with a positive clamping fit-this
willwithstand vibrationand punishingloads without
beingloosened.
D. Propeller and bushing assembly is keyed to shaft
and held in place by compression.
Put bushing loosely into propeller. Do not press or
drive. Start cap-screws by hand, turning them just
enoughto engagethreads intappedholes onpropeller.
Do not use a wrench at the time. The bushing should
belooseenough inthe propellerto moveslightly.
Be sure shaft and keyway are clean and smooth.
Check key size with both shaft and bushing.
Slidepropellerand bushingassembly ontothe shaft,
makingallowance forend playof shaftto prevent
rubbing. Donot forcepropellerandbushingonto shaft.
If it does not go on easily, check shaft, bushing and
key sizes.
Tightencapscrews progressivelywithwrench. Dothis
evenlyasin mountinganautomobile wheel. Take a
part turn on each capscrew successively until all are
tight. These capscrews force the taper bushing into
the hub which in turn compresses the bushing onto
the shaft. This makes a positive clamping fit. The
torque must not exceed that shown in table at left.
WARNING: Do not attempt to pull bushing flange flush
with hub end. There should be 1/8” to 1/4” clearance
when tightened.
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