| 摘要 |
1,109,289. Screw jacks. DUFF-NORTON CO. 3 Aug., 1965 [28 Oct., 1964], No. 33167/65. Heading B8J. A worm gear jack 10 comprises a lifting screw 14 threaded through a worm-wheel 30 driven via a worm-thread 21 and an anti-backlash nut 40 also threaded on the screw 14 and positioned immediately above the worm-wheel 30 to which it is connected by sliding driving pins 42. Backlash of the worm-wheel 30 is minimized by screwing down a shell cap 18 to hold the antibacklash nut 40 and the worm-wheel 30 between thrust bearings 32 and 34, a load being placed on one face of lifting screw-threads 15 by the interior threads on the anti-backlash nut 40, while the interior threads 31 of the worm-wheel 30 place an opposite loading on the threads. An indication of wear of the interior threads of the worm-wheel 30 is given by an offset developing between an upper edge 50 of the anti-backlash nut 40 and an upper edge 19 of the shell cap 18. This wear may be taken up by releasing shell cap set-screws 86 and re-tightening the shell cap 18. Gaps 57 and 59 between the antibacklash nut 40 and the worm-wheel 30 are so arranged that adjustment is limited at a point safely in advance of unsafe wear of the wormwheel thread 31. A single grease fitting 82 is provided, radial lubrication bores (not shown) in the worm-wheel 30 transmitting lubricant force fed by the worm drive screw-threads 21 interiorly of the worm-wheel 30 and thence along the lifting screw-threads 15. |
