| 摘要 |
976,321. Screw - and - nut gearing. R. HALLER. Feb. 13, 1961 [Dec. 16, 1960], No. 5216/61. Heading F2Q. The rotary motion of a driving screw 5 is converted into axial motion of a driven link 22 by mechanism comprising nuts 8, 9 engaging a screw-threaded portion 5a of the screw 5, the nuts being prevented from rotating by an encircling spring 33 having outwardly directed ends 33a, 33b which engage an axial recess in a sleeve 35 secured in a cylindrical sleeve 14 to which the link 22 is attached. The nuts 8, 9 are keyed to a bush 10 and are located axially within the sleeve 14 by bearings 12, 13 and springs 16, 20. The sleeve 14 is adapted to slide axially within a housing 1 by means of rings 27, 28 which prevent rotation of the sleeve 14 by their engagement with a rail 32. On rotation of the screw 5, the spring 33 tightens on the bush 10, preventing rotation of the nuts 8, 9 and causing axial movement of the nuts 8, 9 against the action of spring 16 or 20, until the spring end 33a or 33b reaches the end of the axial recess in the sleeve 35, thereby releasing the braking action of the spring 33 and allowing the nuts 8, 9 to rotate freely. In a modification, the coil spring is in three parts and the surrounding sleeve is provided with recesses adjacent the ends of the spring parts. In another modification, the surrounding sleeve has inclined ramp-like surfaces. In a further modification, the spring is arranged to expand outwardly to frictionally engage the inside surface or the sleeve 14 or bush secured thereto. |
