Fayat Group BOMAG BW 900-50 Service Manual page 65

7.3
Travel pump, PMVO 13S
The boost check valves are integrated in the high pressure relief valves. These valves open to the low pressure
side and let cool and filtered oil flow from the charge oil circuit into the closed hydraulic circuit, in order to com-
pensate leaks and flushing quantities.
Charge pressure relief valve
The charge pressure valve belongs to the group of safety elements in a closed hydraulic circuit. This valve limits
the pressure in the charge circuit to the pre-adjusted value.
Swash plate principle, pump
Fig. 4
The swash plate pump is a positive displacement machine with oil displacing pistons arranged axially to the drive
shaft. The pistons are thereby supported by the swash plate.
Axial piston units based on the swash plate principle with fixed or variable displacement can be used as hydraulic
pumps or hydraulic motors. In pump mode the mechanical energy is converted to hydrostatic energy, when used
in motor mode the hydrostatic energy is converted to mechanical energy. When used as a pump, the flow volume
is proportional to the drive speed and the swashing angle. The available (pump) torque increases with the pres-
sure drop between high and low pressure side.
Variable displacement pumps and motors can be change their displacement, i.e. the pump delivery rate or motor
throughput, by simply changing the angle of the swash plate.
008 921 86 BOMAG 69