Description; Integral Power Steering Gear; Hydraulic Pumps - GMC G Service Manual

3B3-2 POWER STEERING
The hydraulic power steering system consists of a
pump, an oil reservoir, a steering gear, a pressure hose,
and a return hose (figure 1).
INTEGRAL POWER
STEERING GEAR
The power steering gear (figure 2) has a recirculating
ball system which acts as a rolling thread between the
worm shaft and the rack piston. The worm shaft is sup­
ported by a thrust bearing preload and two conical thrust
races at the lower end and a bearing assembly in the
adjuster plug at the upper end. When the worm shaft is
turned right, the rack piston moves up in the gear. Turning
the worm shaft left moves the rack piston down in the gear.
The rack piston teeth mesh with the sector, which is part of
the pitman shaft. Turning the worm shaft turns the pitman
shaft, which turns the wheels through the steering linkage.
The control valve in the steering gear directs the power
steering fluid to either side of the rack piston. The rack
piston converts the hydraulic pressure into a mechanical
1. Pitman Shaft
2. Housing Ball Plug
3. Adjuster Plug
4. Stub Shaft
5. Torsion Bar
6. Adjuster Plug Nut
7. Return Line
8. Stud Bolt O-ring Seals
9. Reservoir
10. Reservoir Cap
11. Reservoir O-ring Seal
12. Pump Shaft Seal
13. Pump Housing
14. Pressure Port Seat
15. Pressure Hose
16. Pressure And Return Port Seat
17. Adjusting Screw Jam Nut
18. End Cover O-ring Seal
19. Side Cover Seal
20. Gear Housing

DESCRIPTION

force. If the steering system becomes damaged and loses
hydraulic pressure, the vehicle can be controlled manually.
two types, submerged and non-submerged. A submerged
pump (P models) has internal parts that are inside the res­
ervoir and operate submerged in oil. A non-submerged
pump (TC models with or without reservoir) functions the
same as the submerged pump except that the reservoir is
separate from the housing and internal parts (figure 3).
housing. The larger opening contains the cam ring, pres­
sure plate, thrust plate, rotor and vane assembly, and end
plate. The smaller opening contains the pressure line
union, flow control valve, and spring. The flow control orifice
is part of the pressure line union. The pressure-relief valve
inside the flow control valve limits the pump pressure (fig­
ure 4).
Figure 1 — Power Steering System — Typical

HYDRAULIC PUMPS

The hydraulic pump is a vane-type design. There are
There are two bore openings at the rear of the pump
B-07320