Working/Lubrication/Shift Pressure, Function - GF27.60-D-3024TSA

Transmission 

725.0 in model 907 

Function requirements for working/lubrication/shift pressure, general 

• Circuit 15ON
• Internal combustion engine running.

Working/lubrication/shift pressure, general 

The oil pressures are separated into:

• Working pressure
• Lubrication pressure
• Shift pressure

Working pressure 

The oil pressure generated by the oil pumps (primary oil pump and electric auxiliary oil pump (M42)) is converted into working pressure by the working pressure regulating valve.

The level of working pressure depends on the position of the regulating valve and therefore on its geometry.

The position of the working pressure regulating valve is influenced by the working pressure solenoids (N15/15y19) depending on the load and gear. All other pressures required for transmission control are derived from the working pressures.

Consumption-reducing and comfort-enhancing measures at the automatic transmission 

The optimized working-pressure reduction enables lower braking power and therefore reduces the fuel consumption. Fuel consumption can be reduced further and the response time to driver load change requests improved by means of controlled minimum slip at low rpm speeds.

Lubrication pressure 

The working pressure regulating valve diverts surplus oil to the lubrication pressure regulating valve, where it is then regulated and used for lubricating and cooling the mechanical transmission and torque converter.

In addition the pressure in the torque converter is limited by the level of lubrication pressure.

Shift pressure 

The shift pressure (pressure in the multidisk clutch or in multidisk brake) is derived from the working pressure.

The respective solenoid valve influences the position of the associated regulating valve. In turn the position influences the pressure prevailing in the multidisk brake or in multidisk clutch. The pressure thus depends on the geometry of the respective regulating valve.

The electrical auxiliary oil pump ensures the oil supply of the hydraulic system when the combustion engine is switched off. It is actuated by the fully integrated transmission control (VGS) electric controller unit (N15/15).

Overview of system components of automatic transmission (AT)

GF27.10-D-9992TSA