Abstract: With a known brake pressure control valve for a dual-circuit brake system, a tilting lever device is provided for the distribution of the preloading force on the control pistons, which increases the change-over point of the brake circuit in operation when the other brake circuit fails. This tilting lever device is complicated in construction and assembly and is not safe in its operation. Therefore, in accordance with the present invention the device for distributing the preloading force comprises two tops each of which is fixed to a different one of the two control pistons. The tops have supporting surfaces on which the preloading device abuts. The adjacent areas of the tops are meshed in such a way that the supporting surfaces of each top extend beyond the median plane located between the control pistons.

Abstract: Twin brake force control units, for a two circuit brake system are known in which the initial control force is changeable dependent on the vehicle load. The control force is distributed to the control pistons by a lever. Due to tolerances and erosion of the individual elements considerable differences in pressure in both brake circuits may occur. This is overcome according to the present invention by providing a lever which directly operates upon both control pistons and which is rotatable about an axis perpendicular to the shifting movement of the control pistons and which is additionally rotatable about its longitudinal axis. This double rotation of the lever is accomplished by supporting the lever in a spherical joint.

Abstract: Pressure control devices with a valve connected between an inlet chamber and an outlet chamber and a non-return valve operating as a by-pass are known. The non-return valve opens due to a reduction in pressure in the inlet chamber relative to the pressure in the outlet chamber against a closing force. This type of known pressure control devices are very expensive to manufacture and are not safe against failure and great erosion. According to the present invention a single arrangement providing the valve and the non-return valve comprises a tappet with a valve body fixed thereto to provide the operation of both valves. The valve body is essentially cylindrical and elastic and its outer surface is spaced from the inner surface of the outlet chamber. The outer surface of the valve body is armored in such a way that a deformation in the radial direction toward the inner surface of the outlet chamber is avoided.

Abstract: Known two-circuit pressure regulators with differential pressure warning indicators are very expensive with regard to production and unreliable with regard to operation. To eliminate these disadvantages, the two-circuit pressure regulator with a differential pressure warning indicator disclosed herein includes an annular leak indication piston having a bore therein that supports and guides the piston shafts of the two regulator valves. The annular piston is so designed that with approximately equal pressures in both brake circuits the annular piston independently assumes its usual central rest position.

Abstract: The braking pressure control unit for a dual circuit brake system comprises a housing with two closure members arranged therein coaxially and in tandem. In their rest position, the closure members are held spaced apart from associated valve seats by a control force. The control force acts directly on a first of the two closure members which in turn bears against a second of the two closure members provided both are in the open positions. At least one closure member consists of a shaft element having one end in an operative relationship with the adjacent end of the other closure member and a closure element in a slidably sealed relationship with the outer surface of the shaft element, the closure element being displaced between limits of the shaft element. A weak closure spring biases the closure element toward its associated valve seat.

Abstract: There is provided a brake-force distributor, wherein the normally controlled rear-axle brake circuit is no longer influenced by the distributor if the front-axle brake circuit has failed. This is achieved by arranging the valve seat at a sleeve held in the operating position by the front-axle brake pressure. In the event of failure of the front-axle brake circuit, the rear-axle braking pressure will displace the sleeve into a position in which the distributor is not allowed to close.