Method for Setting the Working Pressure of a Transmission

A method for setting the operating pressure of a transmission, in particular a motor vehicle shift transmission, the transmission having clutches, brakes, actuators, a hydrodynamic clutch, and/or a hydrodynamic converter, to which a medium conducting the operating pressure can selectively be applied, in order to vary the transmission ratio of the speed and/or the torque between a transmission input shaft and a transmission output shaft by opening and closing the clutches and/or brakes, by actuating the actuators, and/or by hydrodynamic power transmission using the hydrodynamic clutch and/or the hydrodynamic converter,

• the operating pressure being switchable between a constant nominal value and a constant decreased value that is smaller in relation thereto, or the operating pressure being reducible in three or more steps or continuously from a nominal value to a decreased value;
• a speed difference between the transmission input shaft and the transmission output shaft and/or between the input side and output side of at least one clutch, one brake, the hydrodynamic clutch, and/or the hydrodynamic converter being detected and compared to a predefined target difference, and the switching or reduction of the operating pressure being performed as a function of the result of the comparison;
• characterized in that a variable which describes the permissibility of the switching to the decreased value or reduction of the operating pressure, in particular one or more of the following variables:
• the torque applied to the transmission input shaft;
• the torque applied to the transmission output shaft;
• the power applied to the transmission input shaft;
• the power applied to the transmission output shaft;
• the speed of the transmission input shaft and/or the transmission output shaft;
• the power supplied at a secondary drive of the transmission and/or the torque of a drive machine supplied there, in particular of an electric motor;
• the torque applied to a secondary output of the transmission and/or the power applied there;
• the engine drag torque is detected, a limiting value is specified for this variable, which describes the permissibility of the switching or reduction, and the switching or reduction is only performed upon detection of a variable, which describes the permissibility of the switching or reduction, below the limiting value, the limiting value being varied as a function of the result of the comparison of the speed difference to the predefined target difference.