| 摘要 |
A belt guiding roller (3) which is situated transversely to the running direction of the belt (2) is connected at at least one end to a wheel (7). This wheel (7) has on its circumference locking teeth which are engaged with a fixed lock pawl (9) in such a way that the belt guiding roller (3) is freely rotatable when the belt is pulled out, but is locked in the opposite direction. The belt guiding roller has an eccentric, e.g. ellipsoidal, cross-section. A clamping clip (5) which is mounted on the side walls (1) is pressed by means of springs (6) up to a stop (4) against the belt guiding roller (3) and/or onto the belt (2) resting on the latter. When the belt (2) is pulled out, it does not run evenly, but in jerks, because of the ellipsoidal cross-section of the belt guiding roller (3). If the belt (2) is released shortly after a jerk, the retraction mechanism (11) retracts the belt (2) only until the main apex of the ellipsoidal roller circumference clamps the belt (2) between the roller (3) and the clamping clip (5). <IMAGE>
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