| 摘要 |
<p>A hydraulic rock drill has an impact device (15), a revolving motor (16) and an advancing motor (17), the two motors being in series, and pumps and valves required for operation and control. When the impact device is advanced towards the rock, the advance motor admits fluid from a pump (14) and the revolving motor admits fluid from the output side of the advance motor. Pressure of fluid reaching the advance motor is maintained constant with valve and switch assemblies. The other pump is connected to the series circuit including the advance motor and revolving motor so that the two motors are arranged in parallel in relationship to the second pump. Two parallel-connected pressure regulating valves may be connected to the series circuit between the first pump and the advance motor.</p> |
