| 摘要 |
The driver has a hollow outer envelope (1) suspended by a cable (5). Inside the envelope there is an impact mass (2) which can be yoked to a hydraulic jack (13) and can be biassed by a compression spring (10). The spring works against the jack and when it is fully compressed a cam (11a) frees the impact mass by moving the spindle (16) at the end of the jack shaft (15) out of the lifting hook (9). The bottom end of the envelope is closed by a base plate (3) and the impact mass strikes this plate when it is freed from the compression spring. |
