Repair manual

Oil Circulation System
20
Low Pressure Setting Reached
If engine speed increases, the oil pressure increases
slightly and displaces the control piston against the force
of the regulating spring. The pressure port to the front
piston face of the cam lobe unit closes.
At the same time, the connection to the pressureless
return line leading into the oil pan opens. The hydraulic
force exerted by the rear piston face of the cam lobe unit
is now greater than the spring force.
As a result, the cam lobe unit moves against the force
of the compression spring. The driven pump gear is
displaced axially relative to the drive pump gear. The
volumetric flow rate decreases and adjusts to the
engine’s oil consumption. By adjusting the volumetric
flow rate, the oil pressure is kept at a relatively constant
level.
Shortly Before Change-Over
to the High Pressure Setting
The cam lobe unit is fully extended.
Cam
Lobe
Unit
Engine
Speed [rpm]
Relative Oil
Pressure [bar]
Pumped
Oil
Pressure Port
on Filtered
Oil Side
Oil Passage
to Rear
Piston Face
Oil Passage to
Front Piston
Face is Closed
Oil Passage
to Rear
Piston Face
Regulating
Spring
Control Piston is
Pushed Against the
Regulating Spring
Rear Piston Face
of Cam Lobe Unit
Cam Lobe Unit
is Displaced
Compression
Spring of the
Cam Lobe Unit
Driven
Pump Gear
(is displaced
axially)
Engine
Speed [rpm]
Relative Oil
Pressure [bar]