Patent GB-672344-A (GB)
Title: Improvements in and relating to load lowering devices
IPC: B66B17/18
Filed: 1950-02-01
Abstract: 672,344. Lifts; balancing-apparatus; shock absorbers; vane governors. OXLEY, F., PAINE, S. W. T., and ALLEN & CO. (ENGINEERS), Ltd., A. H. Feb. 1, 1950. No. 2641/50. Classes 78 (ii) and 78 (iii). [Also in Group XXVI] An apparatus for lowering loads comprises a platform connected to a counterbalance which is overcome when the platform is loaded but returns it to loading position as soon as the load is discharged, means for constraining the load on the platform so that it is under bias to discharge itself when the constraint is removed automatically on the platform reaching its lowest position, and a locking device for retaining the platform at loading level which is released by the load when the latter is in predetermined position on the platform and is relocked when the platform has risen to loading position after discharge of the load. The platform 1a, Fig. 2, forms the floor of a cage 1 which is guided by vertical shafts 12 and is connected by a rope 5 passed over pulleys 6, 10 to a counterweight 4 which travels between guides 16, 17. Access to the platform at the upper landing is controlled by a vertically slidable door 19 which has depending side legs disposed in the path of the cage so that as the latter approaches the landing the door is raised and vice versa. The raising of the door is facilitated by a weight 19d to which it is connected by a rope 19e passed over pulleys 19f. The sliding door 22 controlling the exit from the cage is provided with buffers 23, Fig. 1, to cushion the impact of the load and is arrested by adjustable stops 33 to free the exit when the cage nears the end of the downward movement. Hydraulic shock absorbers 30, a rubber buffer 25 and spring-loaded stops 32 retard the final stages of the upward and downward movements of the cage. The piston of each absorber is on a long shaft 27 carrying collars 28 which co-operate with brackets on the cage. The cage is locked in the loading position by the engagement of spring-loaded sliding bolts 35, Fig. 1, with the upper surface of fixed members 37. The platform slopes towards the door 22 and preferably is provided with guide ramps or rails. When the load is placed on the platform, it depresses a plate 40 having a depending limb carrying a pulley which bears on a wire 43 attached to the bolt and effects the withdrawal of the latter. Pivoted members 45 are depressed by an entering load and, after it has passed, rise to prevent its return movement. The speed of descent is regulated by a bladed vane 47, Fig. 1, which is driven through multiplying gear by the pulley 6. The blades 48 of the vane may be adjustable and each blade may be provided with a hinged window which opens when the vane rotates in one direction and closes in the other. In a modification, Fig. 10, blades 61 are mounted on the outer ends of angularly movable and slidable shafts 62a, the inner ends of which carry radial pins 63a engaged in helical slots 64a in sleeves 65a. These sleeves radiate from a hub 66b on the main driving shaft 66a in which is incorporated a ratchet or other device to give the fan a oneway action. Tension springs 67a are connected between pins 69 on the hub and pins 68 on the shafts. In a further modification, Fig. 11, a sleeve 75 on the main driving shaft 75a is movable along the shaft by a lever 76 and is provided with radial projections 81 which are connected by cables 82 to pulleys 83 fast on the shafts 84 carrying the fan blades 85. The shafts 84 can be turned against spring pressure to adjust the blades to a chosen angle.