| 摘要 |
1281143 Screw-and-nut mechanism WAHLMARK SYSTEMS Inc 20 April 1971 [8 May 1970] 10152/71 Heading F2Q An anti-friction screw-and-nut mechanism comprises a housing 11 containing a cartridge assembly 21, through which a screw 15 extends, divided into two annular chambers 55, 85 as by end discs 45 and an intermediate spacer disc 30 in which roll ring assemblies 40, 40a internally ribbed at 65 on a diameter greater than the pitch circle of the screw 15 to form a thread of the same configuration as the screw 15 but without any lead so that the threads can be urged into intimate engagement at opposite side of the axis A to prevent backlash. Each ring has an outer bearing surface 61 of less diameter than a sleeve 27 of the assembly 21 and is held between the faces 35, 50, of the discs 30, 45 by roller bearing units 73. The ribs 65 are urged towards the screw 15 by a leaf spring 78, Fig. 2, engaging a bearing 67 for the screw 15. The faces 35, 50 of the discs are inclined on the horizontal plane at the helix angle of the screw 15 on the side of its engagement by the ribs 65 so that the radial thrust engaging the threads acts on the screw 15 at its helix angle. For heavily loaded screws the radial pressure may be set and varied by a set screw. In the embodiment of Fig. 11, the rings are supported for rotation by roller bearings 261 and the disc 230 can be adjusted transversely by a set screw 287 opposed by a leaf spring 285 while screws 290, 291 can vary the length of the housing so that adjustment to take up inaccuracies in the thread 25 is possible. Other forms of adjustable bearing support for the rings are described the adjustment and intimate engagement of the threads prevent backlash and allow wear to be taken up. |
