Abstract: For the determination of the friction/slip characteristics of the tires of a road vehicle which is equipped with an antilock system designed for an individual wheel control, in an initial phase of a controlled braking, only the wheel brake of an individual vehicle wheel is acted upon by brake pressure and the latter is dimensioned so that the result is the initial retardation in accordance with the driver's wish. During this initial test phase of the braking, the absolute brake slip .lambda..sub.B as well as the friction utilization .mu..sub.B linked therewith is continuously determined as soon as, as a result of just the braking of the test wheel, the vehicle retardation z increases no further and/or the braked vehicle wheel is more strongly retarded than corresponds to a predetermined threshold value, the test braking is interrupted and the braking is continued by pressure action on the further vehicle wheels; corresponding test braking phases are carried out in cyclic sequence for all guidance wheels.

Abstract: A slip control system determines friction/slip characteristics of tires of a road vehicle equipped both with an antilock system to permit an individual brake pressure control on individual vehicle wheels. The front wheel brakes are connected to a primary output pressure space of the tandem master cylinder, and the rear wheel brakes are connected to a secondary output pressure space of the tandem master cylinder. A first bore stage of a housing of the tandem master cylinder forms a housing-defined boundary of the secondary output pressure space. An inner piston flange movably seals off a pressureless downstream chamber in relation to an inner portion of the first bore stage. An intermediate wall of the housing delimits the bore stage relative to a central bore stage which extends from a third bore stage receiving a primary piston.

Abstract: An improved method is used to determine speed variation between wheels of different axles of a vehicle. The difference between the speeds of the rear wheels and the speeds of the front wheels is formed, and a correction is determined which compensates for the variations between the speeds of the front wheels and the rear wheels arising because of the vehicle geometry.

Abstract: A motor vehicle with four driving wheels and driven differential gearing for the drive, where (in the case of rotational-speed differences occurring between the wheels) a control device intervenes to distribute the drive power of an engine to the permanently driven wheels and/or the other driven wheels. This intervention occurs for a particular holding time which is progressively extended if a new intervention by the control becomes necessary after a test disconnection of the respective intervention. In addition, or alternatively, the control device can respond more sensitively and thus more quickly to rotational-speed differences of the wheels which may later occur during, or after, a test disconnection.