Impreza RS Coupe AWD F4-2.5L SOHC (1999)
CONTROL VALVE
The control valve consists of a rotor (which rotates together with the steering shaft), a pinion (which is connected to the rotor and torsion bar), and a
sleeve (which rotates together with the pinion). Oil grooves C and D are located in the rotor and sleeve to form oil flow passages Vat through V4.
The pinion and rotor are meshed with adequate clearance. They utilize a fail-safe design.
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Operating principle
When the torsion bar twists in relation to the steering force, a relative rotational displacement occurs between the rotor and sleeve. This
displacement changes the cross-sectional area of oil passages Vat, V2, V3 and V4, which in turn switches oil passages and controls oil
pressure.
