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A ll inform ation pertaining to "POWER STEERING*' (SEC. 9B) in the 1970
Heavy Duty Truck Service Manual ST135-70 is applicable to m odels covered by
this supplem ent. The following inform ation a lso applies.
GENERAL
A ll inform ation in the 1970 Heavy Duty Truck
S ervice Manual ST135-70, page 9-26, pertaining
to the F I60 axle w ill al so apply to the FL901 axle.
MAINTENANCE
NOTE: If for any reason the power steerin g
sy ste m should fa il, the control valve "locks up"
and the steerin g gear operates manually, giving
the driver full control of the veh icle. R esponse of
the steerin g gear in effort applied to the steerin g
w heel w ill be in creased.
Should the power steerin g sy ste m becom es
inoperative due to the lo s s of power steerin g fluid,
one of the following step s should be taken before
the truck is moved under its own power or before
running engine:
1. Make all n e c e ssa r y rep airs, fill and bleed
steerin g sy stem .
2. Rem ove pump drive belt, if pump is driven
by a separate belt from the crankshaft. T his w ill
p revent further p o ssib le damage to the pump while
driving with manual steerin g.
CAUTION : When pump drive belt is
also used to drive the fan o r other engine
components it should not be disconnected.
The pump becomes an idler pulley and if
allowed to run dry would burn up bearing
causing fan to stop and possibly damage
engine further. Do not operate pump with-
out steering fluid in pump re se rv o ir.
3.
If failed component is not at pump, re
route pump p r e ssu r e lin e directly back into pump
r e se r v o ir.
If at the tim e of final repair it has been de
term ined the pump has failed or was damaged to
the point of replacem ent, the entire steerin g sy stem
should be cleaned and flushed out.
Due to scorin g of the pump at tim e of failu re,
the control valve, and cylinder should be d isa s
sem bled and any p a rtic le s of m etal wiped clean
from all p a rts. L ines and h o ses should be rem oved
and blown cle a r . Tag all lin e s a n d h o sesfo r proper
relocation.
SECTION 9B
P a w e b B te e / U r u j ,
MAINTENANCE
The drive belt m ust be kept at proper tension.
A lo o se belt w ill reduce output of the hydraulic
pump, while a tight belt w ill cause eventual b ea r
ing failu re. A regular, p eriodic inspection is r e c
ommended to check condition of drive belt. R eplace
b elt if frayed or badly worn.
ADJUSTMENT
NOTE: When adjusting a new drive belt, adjust
tension to "New" belt sp ecifica tio n s, turn engine
over se v e ra l tim e s, then r e se t belt to "New" s p e c i
fica tio n s sp ecified below:
1. Adjusting P o lv -V B elt Using
Strand gauge (J-23586)
NOTE: Gauge should be placed at the cen ter
of the g rea test span of the belt.
a. Loosen pump mounting b olts.
b. If "Used" belt, position pump to obtain 78
to 88 pounds.
c. If "New" belt, position pump to obtain 103
to 113 pounds.
d. Tighten pump attaching b olts firm ly.
NOTE: A P oly -V belt i s considered "Used"
after one hour's operation or approxim ately 50
m ile s operation.
2. Adjusting Ordinary V -B elt
U sing Strand Gauge (Burroughs B T -3 3 -7 3 -F )
NOTE: Gauge should be placed at the center
of the g rea test span of the belt.
a. Loosen pump mounting b olts.
b. If "Used" belt, position pump to obtain 80
to 90 pounds.
c. If "New" belt, position pump to obtain 120
to 130 pounds.
d. Tighten pump attaching bolts firm ly .
NOTE: A V -b elt is considered "Used" after
two hour's operation or approxim ately 50 to 100
m ile s operation.
NOTE: ALL STEERING COMPONENT A T
TACHMENTS
PARTS IN THAT THEY COULD AFFECT THE
PERFORMANCE OF VITAL COMPONENTS AND
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT
S ec. 9B-181
PUMP DRIVE BELT
ARE
IMPORTANT
ATTACHING
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