GB901995A - Improvements in or relating to hoisting devices - Google Patents

Abstract

901,995. Hoists. ARNOLD, C. H. May 4, 1959, No. 15261/59. Class 78 (5). A winch, intended for sustaining a bosun's chair on a fixed rope 35 and for raising and lowering it thereon, is provided with several safety devices. The chair is secured to the frame of the winch. Drum construction (Fig. 8).-The drum 3 is formed with grooves 40-44 and is associated with fixed guide elements 50-54 so as to allow the rope 35 to be wound in the manner shown to avoid slippage. Hand drive (Figs. 1, 5).-Handle 16 drives drum 3 via shaft 10, gear 9 and gear 10. The connection between handle 16 and shaft 10 includes screw 14, slidable disc 120 and flange 19 fixed to shaft 10. Additionally, ratchet 25 on disc 120 co-operates with pawl 127. Also disc 120 is provided with flange 121 for additional support. Pawl 127 is weighted at 135 to swing tip 126 towards ratchet 25, but also has a biasing spring around its shaft in the opposite direction to bring 136 into a non-locking engagement with the said ratchet 25. The effect is such that, when the winch descends at a slow speed, tip 136 is engaged by the ratchet to cause the pawl to swing back-and-forth. If, however, the handle should be inadvertently released so that the speed is increased, then the ratchet knocks the pawl at 136 to bring tip 126 into engagement with said ratchet and thus to check and hold the winch. The end of the biasing spring may be positioned in any one of the holes 133 formed in the pawl to predetermine the maximum speed thus permitted. Grip of rope on drum (Fig. 1).-This is increased by rollers 95-97 which are pressed by respective springs upon the rope 35 wound upon the drum. Safety lever 76 (Fig. 4).-This is pivoted at 71 and biased by a spring to engage the rope 35 at 79 (not shown). Additionally, shaft 71 carries spring 91 which co-operates with dog 88 which dog engages with gear 8. When the winch is stationary, lever 76 engages rope 35 and dog 88 engages gear 8. To lower, the operator disengages lever 76, which action causes spring 91 to disengage dog 88. Motor drive (Fig. 13).-The handle 16 may be removed and replaced by air motor 140, the motor-and-gear unit being attached to the winch frame by bolts 23, 24, 25. Specification 901,996 is referred to.