| 摘要 |
<p>There is provided a percussion hammer of the type used for driving piles and the like, and including a differential diameter piston defining a ram reciprocally positioned within a differential diameter cylinder. An anvil is mounted for limited movement in one end of the cylinder positioned in the path of the ram to receive percussion blows therefrom. Valve means are provided for controlling the inlet of working fluid and the exhaust of the working fluid from the cylinder so as to cycle the ram through power and return strokes. Safety means are provided for rendering the valve inoperative to cycle the ram when the percussion hammer is out of engagement with a pile.</p> |
