Abstract: A system for the control of couplings in the locking mechanisms or differentials of a drive train in an all-wheel-drive vehicle is disclosed. The drive train of a vehicle having at least two drive axles (4.times.4 vehicle) comprises, starting from the engine and transmission block 1, a power take-off with switchable coupling 2, a front axle differential with locking coupling 3, a rear axle differential with locking coupling 5, steering angle sensor 10, rotational speed sensors 11, status sensors 12 and actuators 13, 14, 15. The rotational speed sensors 11 are installed in proximity to the wheels 4, 6. To be able to automatically switch all the couplings in keeping with terrain conditions, a control system 18 having individual modules (21,24,25) for each coupling (2,3,5) is provided. The control modules (24,25) of the hierarchically lower couplings (3,5) also emit control signals for one or several hierarchically higher coupling(s) (2,5) before they actuate their own couplings (3,5).

Abstract: An interengaging clutch comprises first and second rotatable clutch halves, the first clutch half being a driven clutch element connected to a first wheel drive train and being movable along an axial direction, the second clutch half being a driving clutch element and being connected to a main drive train and to a second wheel drive train. The clutch halves have circumferentially disposed dogs or teeth with intermeshing contact surfaces for engaging the clutch halves together so that torque can be transmitted from the second clutch half to the first clutch when they are interengaged and rotating at different rotational speeds. Connected to the first clutch half is a unidirectional servo component which is pressure actuated on one side only so as to move the first clutch half into engagement with the second clutch. The interengaging clutch further includes first and second rotational speed sensors which produce signals indicative of the rotational speeds of the clutch halves.