| 摘要 |
The prop has a lower tubular section closed by a bottom cover, and an upper section sliding in the lower section and with a piston at its lower end. There is a sealing ring in the top end of the lower section, acting against the upper section and at the upper end of the upper section is a valve housing, connected by an internal tube to the pressure chamber. A preloaded spring inside the tube pulls the upper section down. The tube (13) has ribs (21) extending radially outwards to the inner wall of the upper prop section (2), and there is an elastically-supported prop head at the top end of the upper prop section. |
