| 摘要 |
A driving device, for lifting and lowering the platform of a bed or couch, comprises a support cylinder 1, an axially movable working rod 2 extending into and from the cylinder, the cylinder having a driving section A and a locking section B at which the working rod can be driven and locked, respectively, there being a movable driving piece 3 loosely fitted in said driving section, a driving shaft 4 with a driving protrusion 6 for pushing piece 3 against spring 5 thus driving said working rod forward, a locking piece 7 which is fitted loosely about rod 2 and is pivotably mounted, and a locking spring 8 in said locking section, arranged so that when said driving piece 3 is moved backward by said return spring, said locking piece 7 is urged by the locking spring 8 to engage and lock rod 2, means to pivot locking piece 7 to a position in which it does not lock the rod 2, a moving member 11 also being provided in said locking section to move said locking piece 7 against the locking spring and into contact with a support 12 to hold the locking piece in its non- locking position, and a stopper 13 on the rod 2 for pushing said moving member 11 via a buffer spring 14 towards the support 12 whereby at the end of outward movement of the working rod the locking piece 7 is rendered ineffective automatically. <IMAGE> |
