Subaru 2002 Impreza Service Manual page 355

POWER STEERING SYSTEM
Power Assisted System (Power Steering)
0
When steering force is applied:
When the steering wheel is turned to the right, for example, fluid passages
V1
and
V3
are opened
while fluid passages
V2
and
V4
are nearly closed.
At this point, the fluid pressure in chamber A of the power cylinder increases depending on the
degree of closure of fluid passages
V2
and
V4
so that the rack piston moves to the right. The
fluid in chamber B, on the other hand, is drained through fluid passage
V3
into the reservoir tank.
(1) ChamberA
(2) ChamberB
(3)
v1
NF0290
(7) From fluid pump
(8) To A
(9) From B
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Fail-safe feature
If fluid pressure fails to build up due to, for example, a broken fluid pump drive belt, the steering
wheel rotating torque is transmitted from the valve rotor to the pinion through mechanical engage-
ment between them.
PS-11