GB648043A - Improvements in or relating to control means for hoists and the like - Google Patents

Abstract

648,043. Hoist control. ACROW (ENGINEERS), Ltd., and FOX, H. E. E. Nov. 11, 1948, No. 29362. [Class 78 (v)] Control means for a hoist comprising a pullrope arrangement for operating the winchoperating handle, and in which the pull-rope 50 is formed in two separate lengths normally coupled together by a coupling, a trip mechanism 16 adapted to be operated automatically when the hoist platform or the like overruns a predetermined extreme limit of travel, which trip mechanism then effects an uncoupling of the coupling whereby the operating handle of the winch is released from the pull on the pullrope and is restored to its unoperated brake-on position by means of a biassing weight or spring. Figs. 2 and 3.-The winch control handle is connected by a length of rope to the end of lever 7, which lever is formed with a sleeve 5 pivoting about shaft 2. The separate pull-rope 50 is connected over a pulley to the end of lever 1 formed with a sleeve 4 pivoting about shaft 2. The two sleeves 4 and 5 are drivingly connected by teeth 4a formed therebetween so that when a pull is made upon the pull-rope, the lever 1 is raised, and through the coupling of the sleeves 4 and 5 the lever 7 is raised, thus operating the winch-operating handle to start the winch and to cause the platform driven by the winch to ascend. In order to stop the platform when it rises to its extreme limit and to disengage the pull-rope from operation of the winch handle, there is provided means whereby the two sleeves 4 and 5 can be supported so that no drive passes between them. This means includes a roller 16 formed to pivot at the end of lever 15 together with shaft 14 in a bracket 13, the shaft 14 being fixed to member 12 which engages the sleeve 5 by means of two pins 10 which work in a circumferential slot in the sleeve 5. When the platform rises to its extreme position it engages roller 16 to rotate lever 15 and so to disengage the coupling between the sleeves 4 and 5. Thus, further pulling upon the pull-rope does not affect the drive of the winch and the winch control handle is spring biassed so that it automatically moves back to the braking position and the platform stops whilst in engagement with the roller 16. In order that the platform may be lowered from contact with roller 16, a pin 17 is fixed upon the sleeve 4 so that when the pull-rope is pulled to raise the lever 1 still higher the pin 17 engages a second pin 18 fixed upon the sleeve 5, thus moving the lever 7 so that the winch control handle is partially moved away from its braking position, but not so far as to engage the clutch, so that the platform is permitted to drop. This releases the roller 16 and allows the sleeve 5 to be moved back into engagement with sleeve 4 under the influence of the restoring spring 9. Lever 1 is provided with a weight 1a and with an abutment 7a to limit its movement against the fixed pin 19, which also limits the movement of the pin 17 fixed to sleeve 4. The coupling arrangement and levers are mounted on the fixed guide rails of the hoist platform. The lost motion device may take the form of a suitable stop on the pull-rope, or a telescope connection between the two parts of the rope. The two sleeves may pivot on different axes and the connection therebetween may be " circumferential."