| 摘要 |
A dual circuit brake valve system comprises first and second brake circuits, first and second combined inlet and outlet valves through which first and second braking pressures respectively are delivered to said first and second brake circuits, and first and second pistons which actuate the first and second combined inlet and outlet valves respectively. The second piston is actuated by the first braking pressure which serves as a control pressure therefor. To achieve simultaneous actuation of the first and second combined inlet and outlet valves, a compression spring is installed between the first and second pistons and mechanically connects these to each other. Thereby, a pressure difference of DELTA p between the pressure in the first brake circuit and the pressure in the second brake circuit, which approaches zero, is achieved. In order to be able to increase the pressure difference DELTA p in the two brake circuits, a third piston is provided between the first and second pistons. The third piston is subjected to braking pressure from the first brake circuit in such a manner that the third piston compresses the compression spring when a predetermined level of pressure is reached in the first brake circuit, thereby causing the mechanical connection between the first piston and the second piston to be suspended.
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