The chain-driven oil pump is a gear pump configured as a fixed displacement pump. It integrates the cold start valve and the control piston.
The control piston opens at pressures of up to 3.7 (+0.7) bar. The cold start valve opens at pressures of up to 13 bar.
Function of the pressure regulation system
A bypass branches off from the main oilway and back into the oil pump, where prevailing oil pressure acts on the
spring-loaded control piston. If the pressure acting on the face of the piston exceeds the force produced by the control spring, the control piston will be pushed back, thereby opening a port in the
pump. The surplus oil is thus recirculated to the intake side of the pump until the oil pressure is just below 3.7 bar, when the force of the control spring pushes the control piston back and re-closes the bypass. In this way, a constant oil pressure of 3.7 (+0.7) is maintained.