GF27.57-P-1000LEH Oil Supply For Automatic Transmission, Function

GF27.57-P-1000LEH Oil supply for automatic transmission, function
- TRANSMISSION 722.950

Function requirements for automatic transmission oil supply, general
^ Circuit 87 (connected circuit 15) ON
^ Internal combustion engine in start/stop mode

Oil supply for automatic transmission, general
On an automatic transmission with electrohydraulic control and oil pump drive via the primary shaft, the oil supply fails when the internal combustion engine is switched off. With this, all the control elements and actuators change to a basic state under no load and the automatic transmission power flow stops. When the internal combustion engine is started, and the oil supply has been built up, a gear engagement in the transmission control system must be performed. The resulting loss of time between the start-off request and the start-off time is reduced by the electric transmission oil pump (M42).

The electric transmission oil pump is actuated via the transmission oil auxiliary pump control unit (N89) when switching the internal combustion engine on and off. When the internal combustion engine is switched off, the electric transmission oil pump takes over the oil supply of the control elements and actuators of the automatic transmission.

A check valve is integrated in the pressure line to prevent pressure loss in the hydraulic system if the electric transmission oil pump is switched off.