| 摘要 |
<p>884,567. Screw and nut gearing. ENGLISH ELECTRIC CO. Ltd. March 28, 1958 [April 3, 1957], No. 10874/57. Class 80 (3). [Also in Group XXXVII] In screw and nut gearing particularly applicable to a jack for the raising and lowering of electrical switchgear units (see Group XXXVII) means are provided for locking the screw and nut in one or more preselected positions. A rotatable screw 10 co-operates with a nut 11 adapted to effect a linear movement through a tubular extension 14 of the nut of a member to be controlled. Mounted upon the nut 11 for a limited relative rotation thereto is a tubular member 15 carrying a locking mechanism 12 comprising a radially movable pin 13 on a slider 16 co-operating with one of a number of slots in an extension 18 of the nut 11 and one or more holes 10a in the screw 10. The slider 16 is urged by a spring 17 so that the pin 13 rides along the top of the thread of the screw until it reaches a hole 10a which it then enters to lock nut to the screw. The tubular member 15 is rotated relative to the nut in order to release the locking action by means of a cam ring 22 secured to the member 15 which engages a roller 24 on the slider 16 to move it against the spring 17 and withdraw the pin 13 from the hole 10a. The member 15 is subjected to spring action to reset the locking mechanism for another action but is temporarily held by the roller 24 engaging a notch 22a in the cam ring 22 but is released by a chamfered edge of hole 10a further lifting the pin 13 on renewed rotation of the screw to move slider 16 further and release notch 22a. A series of holes 10a may be provided along the screw for successive locking positions. In assembly the locking pin 13 may be engaged with any of the slots in the nut extension 18 to adjust the locking position and the tubular member 15 together with the mechanism 12 may be adjusted axially to ensure alignment of the pin with the hole 10a. The cam ring 22 may also serve as an additional lock against the slider 16 when the pin 13 is engaged.</p> |
