Chevrolet 70 Series 1970, Service Manual

Page: 717 / 841

STEERING SYSTEM 9-38
Figure 13—Slipper Type Hydraulic Pump
1.45 gallons per minute with pump idling at a speed
of 450 rpm against 665 to 735 p s i p r e ssu r e . The
pump has a maximum flow control range of 3.4 to
4.1 gallons p er minute withalOOOto 1100 p s i p r e s ­
su r e r e lie f v a lv e. The pump is mounted at front of
engine and is b elt-d riv en from the crankshaft.
PUMP OPERATION
A s the drive shaft rotates the rotor, sp rin g -
loaded slip p e r s, which contact the eccen tric diam ­
eter in sid e the pump housing, fo r c e o il from the
inlet sid e of the pump to the flow control v a lv e (fig.
13). P r e s s u r e in sid e the pump is controlled by a
valve which p e rm its fluid to be r e circu la ted within
the pump. Maximum p r e ssu r e in the sy ste m is
lim ited by a p r e ssu r e r e lie f valve which opens into
the r e se r v o ir when p r e ssu r e e x cee d s sp e c ifie d
maximum of
1 0 0 0
to
1 1 0 0
p si.
NOTE: At regu lar in ter v a ls, the fluid le v e l in
the r e se r v o ir should be checked and fluid added
when le v e l is m ore than two in ch es below fille r
cap. R efer to LUBRICATION (SEC. 0) of th is man­
ual, for type of fluid to be u sed .
IMPORTANT: B efore checking fluid le v e l,
sta rt the engine and turn ste e r in g w h eel to the left
and right se v e r a l tim e s to expel a ir from sy ste m ,
then shut off the engine.
PUMP REPLACEMENT
R em oval
1. L oosen two cap sc r e w s w hich attach pump
mounting bracket to engine; then m ove pump inward
and rem ove drive belt.
2. D iscon n ect h o se s at pump. When h o ses are
disconnected, se c u r e ends in r a ise d p osition to
prevent drainage of o il. Install caps at pump fit­
tin gs to prevent lo s s of fluid fro m pump.
3. R em ove two cap sc r e w s and lock w a sh ers
which attach pump and mounting bracket to engine.
Installation
1. P osition pump and mounting bracket on en­
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL