S 65 AMG (221.179) V12-6.0L Turbo (275.982) (2008)
Component Identification
Oil volume regulation
The power steering pump is driven by the engine at alternating speeds. Power assistance however requires a constant oil flow.
As more oil is delivered than necessary at high engine speeds, the excess oil is returned to the reservoir via the open quantity control valve. The
quantity control valve causes a constant volume of oil to be supplied to the steering gear over the entire speed range.
Engine running, steering wheel not turned
The oil pressure generated by the vane cells feeds the oil via the calibrated borehole to the steering gear and also via the calibrated borehole to the
spring chamber behind the quantity control valve.
The calibrated boreholes throttle the oil flow so that in the spring chamber behind the quantity control valve a lower oil pressure prevails than on the
side of the high pressure chamber. The quantity control valve opens and the excess oil flows back into the reservoir.
Engine running, steering wheel turned
The pressure behind the quantity control valve also increases due to the increasing pressure level behind the calibrated borehole. The quantity control
valve closes and remains in its basic position.
Increased engine speed
If the quantity of oil delivered increases as the engine speed increases, a larger pressure difference occurs again due to the calibrated borehole. The
quantity control valve is pressed against the spring and the excess quantity of oil delivered can flow back into the reservoir.