GB382998A - Improvements relating to portable lifting jacks - Google Patents

Abstract

382,998. Lifting-jacks. PARNALL, G. G. and CLARKE, H. V., Coliseum Works, Park Row, Bristol. Sept. 23, 1931, No. 26509. [Class 78 (iii).] Means are provided on a portable lifting jack for adjusting the road wheels, which support the jack during transport, so as to move them out of contact with the ground, the load on the jack then being supported by shoes. As shown, the road wheels 15 are mounted on the cranked ends 14a of an axle 14 which is supported by legs 11 on a frame 3 and provided with a crank 14c carrying a pivotally mounted nut 14d engaging the screwed end of a rod 16. When the jack has been placed in position, a handle 18 is operated so as to rotate the rod 16 and thereby partially rotate the axle 14 and lift the wheels 15. The jack is then supported by the shoes 12 provided with tracks for rollers 13 on the legs 11. The lifting arm 7, carrying the pivoted crutch 8, is raised by a roller 9a on a threaded ram 9 engaging its lower end, the ram being moved by fluid pressure supplied from a reciprocating oil pump 22 operated by a handle 27. The pump piston 22a is connected to a duplex lever 23 which is pivoted to a member 24, rotatable about the piston, and to links 25 pivoted to a nut 26 engaging a thread on the handle 27. The mechanical advantage of the handle 27 may be varied by rotating it about its axis so as to move the nut 26. A nut 10 on the ram 9 abuts the frame 3 so as to support the load and minimize any tendency for leakage of oil past the ram. Castor wheels 19 are carried by a yoke 20, pivotally mounted on a pin 21 projecting from the frame 3.