| 摘要 |
Strap tightener comprises an element 10 for fixedly anchoring the strap tightener, an operating arm 19 pivotally mounted to the anchoring element 10, a strap drum 15 mounted co-axially with the pivot axis, at least one ratchet-wheel 23 connected to the drum for rotation therewith, a catch pawl 25 mounted to the anchoring element 10, and a drive pawl 24 mounted to the operating arm 19, the pawls both being spring-biased to engage the ratchet-wheel 23. The operating arm 19 is drivingly connected to the drum 15 by means of the drive pawl 24 and the ratchet-wheel 23 when swung in one direction and is disengaged from the drum 15 when swung in the opposite direction. A cam element (49, Fig. 4) is arranged on the operating arm for operating the catch pawl to the disengaged position against the spring bias when the operating arm is being swung beyond a predetermined angular position. On the anchoring element 10 a strap lock 37, 38 is arranged for the strap extended to the drum 15, comprising a spring-biased movable clamping jaw 38 for locking the strap against withdrawal from the strap tightener. The operating arm 19 is adapted to engage operatively the jaw at continued swinging movement in the driving direction beyond a second predetermined angular position to operate the jaw to disengaged position while the strap being released from the strap lock to allow withdrawal of the strap from the strap tightener. <IMAGE> |
