| 摘要 |
A protective circuit (40) for pressure and return connections of a hydraulic system. The protective circuit includes a four-way, two-position on/off valve (65) having a first (66), second (68), and third (70) port. In its "off" position, valve (65) connects ports (68, 70) and blocks port (66). In its "on" position, ports (66, 70) are connected and port (68) blocked. A pilot valve (46) is provided including a valve plunger (56) and piston (58), which defines a valve chamber (52) and pilot chamber (54). Valve chamber (52) is connected to pressure and return, while pilot chamber (54) is connected to port (70) of valve (65). A first one-way check valve (96) and second one-way check valve (78) are also provided.
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