| 摘要 |
1,251,050. Pile driving and withdrawing. R. LONDAIS. 21 Nov., 1968 [21 Nov., 1967], No. 55311/68. Heading E1H. A pile (e.g. a hollow pile 8) is driven and/or withdrawn by apparatus comprising a head 1 which is subjected to alternate rotation about the pile axis between stops (e.g. by block 4 on the head hitting stops 6, 7 on a collar 9 secured to the pile) to give the pile torsional impacts, the head being oscillated by two pneumatic jacks 10, 11 supplied alternately by a valve 20 controlled by pneumatic pilot valves 12, 13 operated alternately when the rotational movement changes direction. The jacks 10, 11 and pilot valves 12, 13 may be mounted on the head 1, the member 18 operating the valves being mounted on the collar 9. Restrictors 21 in the lines 19 actuating the change-over valve 20 act to retard the change at the end of each stroke. |
