GB606180A - Improvements in or relating to lifting apparatus - Google Patents

Abstract

606,180. Lifting-apparatus. ELVIDGE, H. May 3, 1945, No. 11301. [Class 78 (iii)] In a lifting-apparatus in which the point of application of the load is at or near the free end of a jib which is pivotally connected at or near its other end at each of two spaced points to a lever or linkage system, the point of application of the load lies at the apex of a triangle having the spaced points at the ends of its base, and the lever or linkage system is such that it acts on the jib to raise or lower it from or to a position in which it is horizontal or approaching the horizontal by both a pivotal and bodily raising.or lowering movement. In the embodiment shown in Figs. 1, 2, 3 the load platform 4 is pivotally supported at 5 on a pair of interconnected jib members 3, each jib member comprising a triangulated structure pivotally connected at 7 and 10 to links 6, 9 pivotally mounted on a trolley. The lifting of.each jib member is effected by a rod 12 pivotally mounted on a nut 14 which is movable along a screw 15 when this is.rotated, rotation of the nut being prevented by rollers 16 thereon engaging guide-ways in outer members 1 of the trolley. Both screws 15 are rotated through chain-and-sprocket devices 20 from a shaft 19 when this is rotated by operation of either of two handles 17. Alternatively, the screws may be power-operated. To ensure a substantially vertical movement of the platform, the foot of the link 9 is pivotally mounted on a nut 21 engaging a screw 22 which is driven slowly through gearing 23 from the screw 15. The inclination of the platform may be adjusted by rotating a screw 27 by means of a handle 29 so as to adjust a nut 26 connected to the platform by links 24, 25. The platform may also be adjusted by mounting the pivots of the arms 6 on brackets 63 which may be slid over supporting platforms 62 mounted on the axle 30 of the wheels 29a. Fig. 4 shows a modification in which the arm 6 is secured to the shaft 31 of a quadrant 32 which is rotated by a band 34 connected to a winch 35, and the link 9 pivotally mounted at 11 on a supporting structure 36. The inclination of the platform may be adjusted through a link 38 pivotally connected at 39 to the platform and at 40 to a nut 41 on a screw 42 which may be rotated by a hand-wheel 43. In another modification, Fig. 5, the arm 6 in the form of a quadrant which is rotated by a cable 44 connected to a winch 45, is pivotally connected at 8 to an arm 46 which during the initial stage of the lifting operation is held stationary by a catch 47. When the arm 6 approaches its limiting upward position (i.e. platform at position 5<1>) abutments 4b, 4g on the jib and link 9 respectively, co-operate whereby the jib and link thereafter move as one arm and on the release of the catch 47 by the engagement therewith of the upper edge of the quadrant 6, the pivot 8 moves about the pivot 7a of the arm 46 and the arm 6 is raised bodily together with the jib and the link 9 and swings about the pivot 11 of the latter to bring the platform to position 5<11>. The inclination of the platform may be adjusted through a link 50 connected to the platform at 51 and to a pivotally mounted arm 53 which is attached to a rack 54 operable by a handwheel 55. To obtain a more nearly vertical lift of the platform, the pivots 7a, 11 of the arm 46 and link 9 may be made adjustable longitudinally by being formed as nuts operating on screws, and the pivot 8 connected to an additional radius arm. Fig. 13 shows a modification of Fig. 1 in which each jib member comprises arms 3, 58 and only one centrally arranged pair of screws 15, 22 is provided. These screws may be replaced by a single screw, the rod 12 being pivoted to the forward end of the cross-head and the link 9 to its rear end. The platform 4 is provided with a structure 70 to form a cradle for objects such as bombs or torpedoes and is adjustable in four ways. It is pivotally mounted on a slide 72 so as to be rotatable about a vertical axis, the slide is mounted for fore-and-aft movement on rollers 74, and these rollers are mounted on a carriage 76 which may be adjusted laterally along a shaft 5 or tilted about the axis of this shaft, the tilting being effected in timed relationship with the raising and lowering means. Two pairs of jib members may be arranged to provide a four-point support for a platform 61, Fig. 12, the jib members being moved in unison. In a modification, the platform 61 is pivotally connected at one end to one pair of jib members and rests at the other end on rollers on the other pair.