| 摘要 |
A hydraulic reciprocating device, e.g. a drill, has a housing, a piston assembly 20, 22 and a means, e.g. rotary valve 30 for intermittently communicating a first piston surface 26 with a hydraulic pressure source. A second piston surface 28 continuously communicates with pressurized fluid e.g. compressed air. The piston assembly moves in a first direction A, to strike a drill bit 46, when the hydraulic pressure source communicates with the first surface 26, and moves in a second direction B when the hydraulic pressure source does not communicate with the first surface. <IMAGE> |
