| 摘要 |
A trailer control valve controllable by means of two circuits, especially for compressed-air brake systems on motor vehicles, is equipped with first and second mutually adjacent control pistons (15 and 21) which are each connected to a circuit and which are movable in the same direction, one control piston (21) carrying one part of the outlet valve (43, 44). The connection (2) of the first control circuit (I) is provided in the vicinity of the first control piston (15) and the connection (4) of the second control circuit (II) is provided at the other end of the housing (1). A hollow control spindle (35) is guided sealingly in the housing for the purpose of connecting the second control circuit (II) and the pressure-medium feedline. In order to achieve a pressure step-up (pressure lead) in respect of the pressure selected in the brake line (9), which can be selected even when there is a defect in one of the two control circuits and also when there is a lowering of the brake pressure, the second control piston (21) is subdivided into an inner balancing piston (22) and an annular piston (23) surrounding the latter, and the inner balancing piston (22) is supported on the annular piston (23) via a restrained spring (30) against a stop (34). Furthermore, the first control piston (15) is subdivided into an inner piston (16) and an annular piston (17), and the inner balancing piston (22) is provided to bear against the inner piston (16) via extensions (29). <IMAGE>
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