Volkswagen Multivan 2010 Service Training page 36

Running gear
Function
At idling speed ...
the cam ring of the pump is pressed against the outer ring by spring force and the internal pressure conditions. This
produces the greatest possible delivery volumes on the suction and pressure sides. The delivery volume increases
as the rotation speed increases, in proportion to the rotation speed.
Pressure relief valve
As the rotation speed rises ...
the pressure in the pump also increases. The pump pressure acts on one side of the control piston, and moves this to
the left against the spring force as the pressure increases. In a defined medium rotation speed range, the ducts to
the chambers between the outer ring and cam ring (left and right chambers) are closed by the control piston. This
equalises the pressure between the two chambers. The cam ring is held in a defined central position, the delivery
volume remains approximately constant.
36
Oil tank
to steering box
Throttle
Compression spring
Pressure hose
Left chamber
Control piston
Rotor
Control line
Outer ring
Cam ring
S453_078
Control piston
Right chamber
S453_080