| 摘要 |
PURPOSE:To allow durability of a brake system to be improved by providing a hydraulic pressure retaining valve, which is installed on the halfway of a hydraulic brake pressure piping system between a master cylinder and a wheel cylinder, with a releaf valve not to allow a retaining brake pressure required for parking a car on an uphill road, to exceed the set pressure. CONSTITUTION:A hydraulic pressure retaining valve 12 which is installed on the halfway of a pair of hydraulic pressure piping systems arranged in a 'X' like form, has a valve body 121 which includes No.1 hydraulic pressure inlet and outlet ports 122 and 123, and No.2 hydraulic pressure inlet and outlet ports 124 and 125. This valve body 121 is equiped inside with both No.1 hydraulic pressure retaining valve which is composed of a ball 129 and a ball valve seat 130, and No.2 hydraulic pressure retaining valve which is composed of a valve body 137 and a valve seat 138. In this case, a releaf valve 144 which is composed of a piston 131 and a spring 132, is incorporated into No.1 hydraulic pressure retaining valve allowing the retaining brake pressure for parking a car on an uphill road to be controlled not to exceed the set pressure.
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