GB277234A - Lifting jack - Google Patents

Abstract

277,234. Nilson, L. D. March 5, 1927. Jacks. -A ratchet and rack and pinion jack having an extended lift combined with a minimum height when lowered, has a lifting member comprising a toothed sector which can be moved from its lowered horizontal position within the jack frame to a vertical lifting position. The frame has spaced beams 11 and is mounted on wheels 15 at one end and has a cross member 17 at the other end carrying castor wheels 18. The lifting member comprises a double toothed sector 19 having pivoted thereto a socket 27 carrying the crutch 28, adjustable by a ratchet device 29. The socket is fitted with guide rods 31 secured to the frame by pin and slot connections 33. The rack teeth 21 on the sector are engaged by pinions 22, Fig. 8, having lateral flanges 25 engaging with the edges of the sector to take the load and also having between them a ratchet wheel 23. The lifting pawl 36 is carried by a pair of plates 38 loosely mounted on a shaft 13 and the plates are connected by links 42<a> to a toothed quadrant 43 on a, shaft 32. The operating lever 44 is adjustably connected to the quadrant 43 by means of a toothed block 40, the quadrant also having a pedal 74 for foot operation when raising the jack to the load. The holding pawl 51 is mounted on a shaft 52. A tension spring 48 connected to the frame and to the linkage 42<a> normally holds the lifting pawl in its starting position. In operation, the lever 44 is rocked and through the lifting pawl rotates the ratchet wheel and pinions. and raises the sector and crutch, the holding pawl functioning in the usual way. To lower the jack, a bent lever 73 is rocked and through its spring-pressed connecting linkage 68 engages a notched head 59 with a pin 62 on an extension arm of the holding pawl. The head 59 forms an extension of a rod 58 sliding in a block 57 mounted on an extension arm of the lifting pawl and positioned on the rod by opposed springs 66. With the parts in this position the pawls are interconnected and by rocking the lerer 44 the opposed springs 66 are alternately compressed and expanded, the arrangement being such that the pawls are engaged and disengaged alternately and so lower the load step by step.