POWER STEERING 2A – 9
The hydraulic power steering system consists of a
pump, an oil reservoir, a steering gear, a pressure
hose and a return hose.
POWER STEERING GEAR
The power steering gear has a recirculating ball
system which acts as a rolling thread between the
worm shaft and the rack piston. When the worm
shaft is turned right, the rack piston moves up in
gear. Turning the worm shaft left moves the rack
piston down in gear. The rack piston teeth mesh
with the sector, which is part of the sector shaft.
Turning the worm shaft turns the sector 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 force. If the steering
system becomes damaged and loses hydraulic
pressure, the vehicle can be controlled manually.
HYDRAULIC PUMP
The hydraulic pump is vane-type design.
There are two bore openings at the rear of the
pump housing. The smaller opening contains the
pressure line union and flow control valve.
PRESSURE SWITCH (6VD1,
6VE1 Engine)
When hydraulic pressure reaches 3650 ± 350 kPa
(530 ± 50 PSI), the pressure switch closes causing
ECM to actuate the idle air control valve to prevent
the overload-induced engine speed down. The
switch opens when hydraulic pressure drops to
3150 ± 350 kPa (460 ± 50PSI).