| 摘要 |
The hydraulic switch system, for the operation of two double-action working cylinders, has a main control valve (22) at the hydraulic pump with one outlet (A) linked directly to the piston base zone (14) of the first cylinder (10), and a second outlet linked directly to the piston rod zone (20) of the second cylinder (12). One outlet (A,B) selectively connects the hydraulic pump and the tank. A change-over valve (30) is held in one setting by a spring (32) linked to a control inlet (34), to link the piston rod zone (18) of the first cylinder (10) with the piston base zone (16) of the second cylinder (12). A self-sustaining pressure valve (40) has an inlet linked with the feed (24) to the piston base zone (14) of the first cylinder (10) and its outlet is connected to the control inlet (34) at the first change-over valve (30). On switching the first pressure valve (40) on a given pressure into a second setting, both cylinders (10,12) operate in parallel and the control inlet of the first pressure valve (40) is constantly linked to the second outlet of the main control valve (22). A second pressure valve (52), at a given pressure level, has its inlet linked to the second outlet (B) of the main control valve (22) and its outlet is also connected to the control inlet (34) of the first change-over valve.
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