| 摘要 |
PURPOSE:To enable the piston to spring up after being hit in a device wherein the body to be hit is hit by the reciprocating piston, so as to save power and energy, by providing a ckeck valve in the passage connecting the pressure rooms on both sides of the piston of the differential cylinder. CONSTITUTION:A pressure room 2 having a smaller pressure receiving surface of a differential cylinder 1 is connected to a pump 6 via fluid passage 4, 5, whereas a pressure room 3 having a larger pressure receiving surface is connected either to a fluid passage 5 connected, in turn, to the pump 6, or to a return passage 10 connected to a tank 10, via a direction switchover valve 8. The direction switchover valve 8 is controlled by the fluid pressure introduced to a pilot chamber 15. Furthermore, in this device, a passage 26 which connects the pressure room 2 to the pressure room 3 is formed in the piston 11 and a check valve 27 allowing the fluid to flow only from the pressure room 3 to the pressure room 3, is arranged in the passage 26. Thus, when the piston strikes the body to be hit, it is allowed to spring up freely, and as a result the pump driving power is saved in the return process. |
