| 摘要 |
PURPOSE: To facilitate height adjustments by causing the release element of a stopping device to describe a track on which the release element meets the next lower stopping element when energized and during the falling motion of an anchoring element. CONSTITUTION: A release element 42 is normally pressed toward an unenergized position by a spring 46, and an actuator extension 42B is on a pawl 32 or 34 in a stopping position. When the actuator lever 42A of the release element 42 is pressed downward, the pawls 32, 34 are pressed toward a release position via the actuator extension 42B, and a stopper portion 40 is released from the pawls. Therefore an anchoring element 12 can be moved downward. During this movement an actuator 42A is depressed and therefore a block extension 42C projects into the path of movement of the stopper portion 40. Hence the extension 42C is locked to the next pawl 34. The next position is thus surely detected, and height adjustments can easily be made. |
