| 摘要 |
The invention relates to a safety switching system for a clamping device used for holding and/or lowering and raising a line of pipes (13) lining a borehole. Said safety switching system is mounted inside the clamping device, where it is protected from external mechanical influences. To this end, a shift cam (18) for a safety shift valve (1, 2) is fastened to the clamping wedge support (14a, 14b) of the clamping device. This valve is mounted on the base (10) of the clamping device, and cooperates with the shift cam when the clamping wedges (12a, 12b) adopt their prescribed clamping position on the line of pipes. |
