Working/Lubrication/Shift Pressure, Function - GF27.60-P-3024ANE
Transmission 725.0 in model 463
Function requirements, general
- Terminal 15 ON
- 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 transmission 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 solenoid valve (Y3/8y19) depending on load and gear. All other pressures required for transmission control are derived from the working pressures.
Fuel 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.
Lubrication pressure
At the working pressure regulating valve, excess oil is routed to the lubrication pressure regulating valve where it is used to regulate the lubrication and cooling for the mechanical transmission components, and the torque converter (transmission 725.035) or the wet clutch (transmission 725.085). The level of lubrication pressure also limits the pressure in the torque converter (transmission 725.035) or the wet clutch (transmission 725.085).
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 electric transmission oil pump ensures a continued supply of oil to the hydraulic system when the combustion engine is switched off.
The oil supply is dependent on the transmission oil temperature and the required volumetric flow rate. Actuation is performed via the fully integrated transmission control unit (Y3/8n4).
| Overview of system components for automatic transmission (AT) | GF27.10-P-9992ANE |