| 摘要 |
The invention is intended to enable precise measurements with the aid of a dial gauge of the strain of a screw when it is tightened. For this purpose, a feeler pin (3) is arranged in a precise bore (2) on the screw axis and pressed with its lower end in the free end of the screw shank. The surface of the screw head (4) is ground flat with the upper end face of the feeler pin (3), which projects with play through the screw head (4). The screw head has a centre (5) for a holder (6) with an attached dial gauge (7). The magnetic holder (9) of a permanent magnet (10) is rotatably mounted in the holder (6), which is sub-divided by a vertical joint (11) into two magnetically non-conductive halves which are soldered together. A rotary ring (12) which is connected to the magnetic holder (9) by screws (13) is fitted on to the holder (6). The magnetic holder (6) is sealed from above downwards by a cover (15) into which the dial gauge (7) is screwed. <IMAGE> |
