GB726658A - Improvements in or relating to lifting devices - Google Patents

Abstract

726,658. Load handling appliances. LUDOWICI, J. W. June 26, 1951, No. 15136/51. Class 78 (3). [Also in Group X] A lifting device comprises two or more lazy tongs structures, whereby the end of one link of each structure is pivotally secured to a fixed point on a frame member and the end of another Ink is pivotally and slidably guided in a slot in the frame member, the frame members being rigidly interconnected either in spaced relationship or at an angle to one another, whilst all links of each lazy tongs structure are similarly interconnected at the end joints or at an end joint. Fig. 2 shows two systems of pivoted links 1 the end of one link being pivoted at 4 to a frame member and another end being free to slide in a slot 10. The systems are interconnected by rods 12, and the links may be alternatively long and short to collapse one within the other. The systems may be combined at an angle or to form a T-shape, a triangle or a square in plan. In Fig. 9 are shown stiffening rods 16, 17 pivoted to the end joints of the crossed links 1 and which are extended with the framework and assist in supporting the structure. Detents with latches may be arranged at the joints 19 or torsion springs. The crossing points of the links may be off centre to describe an arc when extended. The links may be extended by a piston and cylinder or screw and nut or by a cable wound on a winch of conical shape or in layers on a ring winch. A platform may be supported at the top of the linkage at 20. As shown in Fig. 16 a platform 35 is supported by a lazy tong linkage and a hoisting rope 27 secured at one end to the platform passes round rollers 37 situated at the end points of the links round rollers 38, 39, 40, 42 to 45 and reversing rollers 40 to a conical winch drum 46. The reversing rollers 40 are mounted on extensions of the platform whereby when the winch is operated the hoisting is first assisted by the roller arrangement. Alternatively a roller may be attached to an end link and engaged in a bight of the hoisting rope, or the platform may be supported on pistons mounted on springs in cylinders. A collapsible stairway may be located along one link of the lazy tong or at one edge the interior of the system being used for a lift or the stairway may pass through the central pivots. The system may be used for a hoist fitted with two guides the system supporting rollers to engage the hoist which may be winch operated.