| 摘要 |
789,472. Screw and nut mechanism. AMERICAN METAL PRODUCTS CO. July 26,1955 [Jan. 13, 1955], No. 21554/55. Class 80 (3). In a screw and nut mechanism for effecting a translational movement of a member by the nut on rotation of the screw, the nut is coupled to, and normally prevented from rotating by, the driven member but is adapted to be released to rotate freely when the load exceeds a predetermined amount. The nut 14 is rotatably mounted by ball bearings 19 in a housing 15 which is coupled to the member to be driven (not shown) engaging in oppositely disposed apertures 22 of the housing. In Fig. 4 the nut is prevented from rotating by a spring-loaded ball or roller 25 engaging in an axial slot 23 in its periphery. When an excessive load is encountered, as by the nut engaging limiting pins 37 on the screw 11, the ball 25 is forced out of the slot 23 to allow the nut to rotate with the screw. In Fig. 3 the ball 25 is adapted to be held in engagement with the slot 23 by means of a solenoid 28 on energization thereof and is forced out on excessive load against the electromagnetic force. A spring catch 55 may be provided to retain the ball 25 and armature 27 after being forced downwardly but which is released on de-energization of the solenoid. This arrangement allows one of a plurality of nuts on a single screw to be brought into operation selectively as desired. These nuts may be used for actuating a vehicle body seat backwards or forwards or up and down. |
