| 摘要 |
755,096. Hydraulic actuation of switches. GRATZMULLER, J. L. Dec. 10, 1954 [Dec. 24, 1953; July 30, 1954], No. 35772/54. Class 38(5) In a single-acting hydraulic jack which is actuated by liquid pressure against a counteracting force, means are provided giving a discharge rate of liquid greater than the feeding rate so that the return stroke of the jack is quicker than the forward stroke. The jack may be used to set a circuit breaker into contact-making position against the action of elastic means. A jack comprises a cylinder 3 and a, piston 4. a spring 5 ensuring the return stroke. For the forward stroke liquid from an accumulator 6 passes through ducts 8, 10 to the upper end of a cylinder 12 containing a piston 13, and through a passage 20 and past ball valve 21 in the piston to the lower end of the cylinder, thence through a port 14 to the jack cylinder. A spring 27 urges a valve 18 integral with the piston 13 on to its seat to close an outlet 15a. If a valve 7 is turned to connect the duct 8 to exhaust, piston 13 is raised, removing the valve 18 from its seat and enabling the liquid in the jack to pass to exhaust. The spring 27 may be replaced by a spring facilitating opening of the valve 18, in which case the spring urging the ball valve 21 to its closed position is strong enough to ensure sufficient differential pressure to hold valve 18 on to its seat.
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