| 摘要 |
A gripping means consisting of two jaws (2, 3) pivotable in relation to each other on a shaft (32), said shaft (32) being secured to one jaw (3) and extending through a sleeve (53) secured to the other jaw (2), the shaft (32) having an enlarged section (39) adjacent to and having substantially the same outer diameter as the sleeve (53). A tightly coiled helical spring (70) surrounds both the sleeve (53) and the section (39). One end portion of the spring (70) is freely movable on the enlarged section (39) and can be rotated at least in one direction in relation thereto. The other end of the spring (71) is connected to a roller (4) which is pivotably journalled and can be turned upon peripheral contact with a tread surface (9A, 9B) arranged at a desired position along the path of the gripping means so that the gripping means opens at a position exactly defined by the tread surface (9A, 9B). |
