Patent GB-661552-A (GB)
Title: Improvements relating to lifting apparatus
IPC: B66F9/02
Filed: 1949-12-08
Abstract: 661,552. Lifting and lowering; hoists; lifts; winches and endless conveyers. STEADMAN, A. H. Dec. 8, 1949. No. 31522/49. Classes 78 (i), 78 (ii), 78 (iii) and 78 (iv). A load lifting platform is secured to corresponding runs of a pair of endless ropes and is lifted by attaching a counterweight, previously lifted independently by a hand winch, to the other runs of the ropes and thereafter allowing the weight to fall under gravity. As shown diagramatically in Fig. 1, the endless rope A passes around guide pulleys B and its laps 1 and 3 are secured to the lifting platform 5 whilst its laps 2 and 4 are secured to the counterweight container 6. In the construction shown in Fig. 3 this rope arrangement is duplicated on each side of the platform and the container 6 is fitted with spring catches 7 which automatically engage the counterweight 8 when it has been lifted by the hand winch 19 and which are disengageable, at will, to allow the empty platform assembly, which is slightly heavier than the empty container, to descend under gravity. The winch, Fig. 6, is controlled by two band brakes 27, 28 and the manner of operation is as follows. With brakes 27 and 28 on, sun wheel 20 is held from rotation and thus manual rotation of shaft 15a rotates the planet cage 19, which constitutes the winch drum, so that the weight 8 is lifted into engagement with the carrier. On release of brake 28 the sun wheel 20 and shaft 21 are free to idle so that further rotation of the shaft 15A does not overwind the drum which, due. to a ratchet wheel 23, secured thereto, and a pair of pawls 26 secured to a drum 25 held from rotation by brake 27, can not unwind until the brake 27 is released. When this occurs the counterweight drops, the load is lifted and after the load has been removed from the platform 5 and the catches 7 ha.ve been released from the weight, the apparatus returns to its initial position. The brake 27 is controlled manually but operation of the brake 28 is automatically controlled by a control rod E shown in Fig. 7 in the position where the counterweight has been raised and the brake has been released. After the counterweight has been released and it has nearly reached the bottom it engages a foot 30 which causes a collar 31 to depress a sliding sleeve 32 which, through a spring 33, exerts a force on the brake lever 34 at the same instant as a cam 29 un the rod E contacts a roller 37 and releases the lever 34 from a pivoted catch 35 thus the brake 27 is applied. This locks the sun wheel 20 again and, since the shaft 15a is held from reverse rotation by a ratchet and pawl (not shown), arrests descent of the counterweight. On rewinding, as the counterweight reaches the top it engages the sleeve 32 which lifts the collar 31 so releasing the catch 35, and, simultaneously, due to the reduction of tension in the spring 33, the natural spring in the brake band disengages the brake so releasing the sun wheel 20 and stopping further winding. Endless conveyers. The shaft 15a may be coupled to the driving shaft of a detachable conveyer (not shown) which serves to load a sack on the lifting platform while the cuunterweight is being raised.