GB1086290A - Lifting device - Google Patents

Abstract

1,086,290. Lifting-Jacks. AERONAUTICAL MACHINERY CORPORATION. Dec. 22, 1965 [Jan. 11, 1965], No. 54430/65. Heading B8J. A lifting-jack comprises a truck frame 10 having two side pieces 11 arranged to receive partially therein two support arms 12, respectively, in inoperative position and spaced by an opening 13 to receive therein in inoperative position a lifting lever arm 14. The support arms 12 are pivotally secured at their forward ends to the side pieces 11 by aligned pivot pins 28 and at their rearward ends to the lifting lever arm 14 by aligned pivot pins 27. The lifting lever arm 14 is powered into elevated position through the support arms 12 by means of two telescopic hydraulic or air pressure rams 30 each pivoted at one end to one of the side pieces 11 by a pin 32 and to one of the support arms 12 at the other end by a wrist pin 35. The angular movement of the lifting lever arm 14 about the axes of the pins 27 is controlled in such a manner as to cause a lifting head 70 on the forward load bearing end of the lifting lever arm 14 to follow a substantially vertical straight path by horizontally guiding the rear end of the lifting lever arm 14 by guiding means 49 provided in conjunction with a housing 15. The guiding means 49 comprise rollers 65 riding on rails 57 and rollers (101), Fig. 15 (not shown), riding between upper and lower guide strips (51) and (54) respectively. The lifting head 70 is maintained horizontal by a parallel motion mechanism comprising a stabilizing arm 90. When the lifting lever arm 14 has reached its lifting limit the load can be transferred to a screw jack 25 pivoted at 85 to the lifting head 70 and, when in inoperative position, nested in the lifting lever arm 14. The truck frame 10 is supported on a pair of front wheels 16 and a pair of rear wheels 17. A pair of spring-loaded castor wheels 20 raise the forward end of the jack when it is not loaded. A pair of stabilizing brakes 22 lock the jack in position against movement along the ground while under load. A jack pad 75 is adapted to fit a jack point (not shown) secured to part of the load, e.g. the underside of the tail or wing of an aircraft to be lifted. The jack pad 75 operates for that purpose, not only during the full lift of the lifting lever arm 14 but also during the additional full operation of the screw jack 25 without changeover in the jack point of support, the jack 25 being released from its nested position, where it is retained by a chain (118), Fig. 5 (not shown), when the lever arm 14 has been fully raised.