A drive force transmission apparatus is mountable on a four-wheel drive vehicle switchable between a four-wheel drive mode that transmits a drive force of an engine to front wheels and rear wheels, and a two-wheel drive mode that transmits the drive force to only the front wheels. The drive force transmission apparatus allows adjustment of the drive force to the rear wheels, and includes a multi-plate clutch, a piston for axially pressing the multi-plate clutch, an actuator for axially moving the piston, and a control unit for controlling the actuator. Upon satisfaction of a predetermined condition that indicates a high probability of the vehicle needing to be switched from the two-wheel drive mode to the four-wheel drive mode, the control unit causes the actuator to displace the piston by a predetermined amount with respect to an initial position of the piston toward the multi-plate clutch.

A method for operating a drive train by providing a primary drive machine, a working machine, a hydrodynamic clutch, and a temperature detection device; wherein at least in the case of a change from a load state and/or an operating state of the drive train thereby creating a new load state and a new operational state, the temperature of the hydrodynamic clutch is detected at the time of the change; wherein on the basis of the detected temperature and the new load state and/or the new operational state of the drive train, an expected temperature progression is calculated; and wherein a warning signal and/or a stop signal is issued for the primary drive machine if a temperature of the calculated temperature progression exceeds a predetermined maximum temperature within the expected duration of the new load state and/or the new operational state.

The invention relates to a method for avoiding safety-critical activation of a clutch in a hybrid module of a drivetrain of a motor vehicle, wherein the hybrid module is effective between the internal combustion engine and the transmission and has an electric drive, the clutch and a freewheel, and the clutch is used to start the internal combustion engine by transmitting a torque, supplied by the electric drive or the drivetrain, by a frictionally locking connection to the electric drive or the drivetrain, or for disconnecting the internal combustion engine from the drivetrain for purely electric driving. In a method for avoiding safety-critical activation of a clutch in a hybrid module in which safety-critical driving situations are reliably prevented, a critical interference torque of the clutch is set as a function of ambient conditions of the motor vehicle and/or peripheral conditions of the vehicle, in order to set a safety distance to be maintained by the open clutch.

A system and method for controlling a powertrain, comprising an internal combustion engine connected to a double clutch transmission having a first and a second partial transmission with at least one shiftable transmission stage. A first friction clutch is arranged between the internal combustion engine and the first partial transmission, and a second friction clutch is arranged between the internal combustion engine and the second partial transmission. An engine torque of the internal combustion engine is transmitted by the first and second friction clutches to the first or second partial transmissions to provide a drivetrain torque at the output of the double clutch transmission. The powertrain is monitored for an occurrence of juddering oscillations, wherein in response to juddering oscillations being detected a regeneration process of one of the first and second friction clutches is triggered, and a friction lining is removed in the regeneration process.

A vehicle heating system having a first viscous clutch and a pump and viscous clutch mechanism. The first viscous clutch has a first clutch input member. The pump and viscous clutch mechanism has a pump and a second viscous clutch. The pump includes a pump input member, while the second viscous clutch includes a second clutch input member. One of the pump input member and the second clutch input member is drivingly coupled to a portion of the first viscous clutch.