Abstract: An actuator for activating a parking lock, in particular for automatic transmissions in motor vehicles, includes a hydraulic piston which is guided in a cylinder and which activates a locking pawl for a parking lock wheel in the transmission by way of an actuating rod. The piston disengages the parking lock against the force of a preload spring which engages the parking lock in the pressureless state. An electromagnetically activated locking device can positively secure the piston in the disengaged position, with the locking device securing the piston relative to a guide sleeve attached to the cylinder with radially extendable locking elements. To improve system protection, the piston can also be secured in a positively locking fashion by the locking device in the position corresponding to the engaged state of the parking lock.

Abstract: A transmission assembly has a clutch or brake, an oil filter, an electrically driven hydraulic pump and a controller controlling the pump. In the method for operating an oil filter system for transmission oil, the actual contamination level Va (%) of the transmission oil is determined indirectly by a contamination model Va (%)=Vstart(IW %)?A (%)+B (%)+C (%), wherein Vstart (IW %) is a starting contamination value, A (%) depends on the hydraulic pump flow rate, B (%) depends on a clutch energy input, and C (%) depends on a transmission performance. When a contamination threshold value Vs (%) is exceeded, the hydraulic pump is switched on, until the actual contamination level Va (%), after decrementing by A (%) in the contamination model, is equal to or less than the contamination level threshold value Va (%) minus a fixed hysteresis value VH (%).

Abstract: According to a method for operating a clutch transmission, especially a dual clutch transmission, which includes a hydraulic circuit having at least one pump for delivering hydraulic medium and at least one pressure accumulator for accommodating and making available a hydraulic medium under pressure, the pump associated with an electric motor is operated depending on a charge requirement of the pressure accumulator. To determine the charge requirement, the pump is driven by the electric motor, and the current consumed by the electric motor in the process is detected to determine the charge requirement.

Abstract: A dual clutch transmission, especially of a motor vehicle, includes a hydraulic circuit with a pump for delivering a hydraulic flow, a cooler for cooling the hydraulic flow, and a volume control valve for adjusting the hydraulic flow for a cooling system associated with two clutches of the dual clutch transmission. The volume control valve is constructed as a switching valve with at least two switching position ranges, supplying the hydraulic flow to a first cooling system associated with a first clutch in a first switching position range with a constant flow cross-section, and supplying the hydraulic flow to a second cooling system associated with a second clutch in a second switching position range with a constant flow cross-section, wherein the entire switching position range of the volume control valve is substantially formed by the first and second switching position ranges and only a narrow transition range therebetween.