Subaru 2002 Impreza Service Manual page 354

POWER STEERING SYSTEM
Power Assisted System (Power Steering)
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Principle of operation
When the torsion bar is twisted by a rotational force applied to the steering wheel, the relative posi-
tion between the rotor and sleeve changes. This changes the cross-sectional area of fluid pas-
sages VI ,
V2, V3
and
V4.
The fluid passages are thus switched and the fluid pressure is controlled
in accordance with the operation of the steering wheel.
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When no steering force is applied:
The rotor and sleeve are held at the neutral position. Fluid passages VI,
V2, V3
and
V4,
which
are formed by grooves C and D are open equally. Under this condition, the fluid from the pump
returns to the reservoir tank so that neither fluid pressure builds up nor the rack piston moves
in the power cylinder.
(1)
ChamberA
(2) ChamberB
(3) VI
PS-10
NF0288
(7) From fluid pump
(8)
To A
(9) To B