| 摘要 |
1,259,328. Percussive tools. GARDNERDENVER CO. 6 Oct., 1969 [16 June, 1969], No. 49025/69. Heading B4C. A percussive tool comprises a hammer piston 16 reciprocable in a cylinder 12, a distributing valve 24 for alternately directing pressure fluid supplied via pipe 28 into chambers 56, 80, and a throttle for reducing the flow of fluid to the distributing valve actuable in response to fluid in chamber 56 reaching a predetermined pressure. When this pressure is reached, i.e. when tool bit 52 is subject to a " no-load " condition, check valve 60 will be opened to permit the fluid to flow into chamber 72 and thus move throttle member 74 to throttle the flow of fluid via passages 30, 32, 34. In an alternative embodiment (Fig. 2, not shown), the fluid from chamber (56) when the predetermined pressure is reached, flows past a check valve (92) and actuates a valve (96) to connect chamber (98) housing the throttle member (102) to a source of pressure fluid. In the inoperative condition of the valve (96) the chamber (98) is connected to atmosphere. |
