GB514502A - Improvements in hoists - Google Patents

Abstract

514,502. Winches STANCLIFFE, C. W., and WINGET, Ltd. May 7, 1938, No. 13701. [Class 78 (v)] The winding drum 6 of a hoist is journalled freely on a continuously rotating power shaft 1 and is coupled thereto at will by an expanding spring coil 11. The coil 11 surrounds the shaft 1 and lies within a sleeve 8 held non-rotatably relative to the drum 6 by teeth 9, 10. 'One end of the coil 11 engages an abutment 12 on the shaft 1 and its other end abuts against a stop 13 on a drum 14 frictionally mounted on the shaft 1. Normally the shaft 1 pulls the coil 11 tightly around it, both coil 11 and the drum 14 rotating with the shaft. By tightening a brake band 15 around the drum 14, however, the latter is retarded and the coil 11 expands to bear against the inner face of the sleeve 8 and rotates same together with the drum 6. To prevent the load unwinding the cable 16 from the drum 6 when the latter is not being driven a self-sustaining device is provided comprising a spring coil 23 attached at one end 24 to an extension 21 of the drum 6, the coil 23 lying closely within a drum 18 loose on the shaft 1 and provided with a brake band 20. When the drum 18 is held stationary by the band 20 rotation of the drum 6 in the unwinding direction tends to expand the coil 23 and prevent further motion of the drum 6. Fig. 2 -shows an arrangement whereby both drums 14 and 18 can be operated from a single control lever 39, which is connected by a shaft 38 to a cross bar 37. One end of the bar 37 bears on the free end of a 'lever 32 pivoted at 33 to release the drum 18, and the other end of the bar bears on the free end of a lever 26 pivoted at 25 to apply the band 15 to the drum 14. Thus rocking of the arm, 39 one way allows the drum 6 to unwind and the other way couples the drum 6 to the shaft 1. An extension 40 on the lever 39 lies in the path of the load at its topmost position, thus automatically disconnecting the drive from the winch drum and preventing application thereof till the load is lowered. The device is stated to be applicable to concrete mixers and like machines,.the pinion 5 shown being for the purpose of rotating the mixing drum.