| 摘要 |
PURPOSE:To obtain a great striking force by increasing the dropping speed of a ram by using a system in which when the ram is dropped, working liquid in the lower chamber of the first cylinder chamber is sent into the upper chamber of the second cylinder chamber. CONSTITUTION:When a solenoid valve 54 is switched to I -position, the working liquid discharged from a main pump 47 is supplied through the first port 35 into the lower chamber 31b of the first cylinder chamber 31 in a cylinder 30, and thereby the first piston 41 is raised to lift up a ram 40. When the solenoid valve 54 is then switched to II-position, the working liquid is supplied through the second port 36 into the upper chamber 32a of the second cylinder chamber 32. Therefore, the ram 40 and the pistons 41 and 42 are free-dropped altogether and the pile 56 is driven into the ground. |
