GB545645A - Improvements in or relating to overrun protective gear, applicable to winding drums - Google Patents

Abstract

545,645. Overwinding prevention. WELLMAN SMITH OWEN ENGINEERING CORPORATION, Ltd., and STOCKDALE, S. Feb. 28, 1941, No. 2761. [Class 78 (v)] An overrun protective device for winding drums comprises a gapped cam 11 on which rides a roller 14 controlling a snap-over lever 28 which actuates a switch in the motor circuit or a clutch between the motor and the winding- drum shaft. The roller 14 is carried on one arm 15 of an articulated pad lever pivoted at 17, the other arm 16 of which carries a laterally projecting pin 19 riding in a groove 20 in a sleeve 21 slidable along the winding drum shaft 5. The sleeve 21 has a radial projection 25 which either clears the two-pronged lever 28 pivoted at 29, or engages therewith, dependent on the location of the sleeve 21 on the shaft 5. The cam 11 is rotated from the shaft 5 through worm gearing 6, 8 and one, 12, of the lips of the gap is enlarged and turned outward to press away the roller 14 and rock the lever 15, 16 against the pull of a spring 24, so shifting the sleeve 21 laterally into the position where it can engage the prongs 26 and snap over the switching lever 28. If during the wind the cam 11 makes more than one revolution, a face 12a on the lip 12 guides the roller 14 within the cam, where it may meet a snail conformation permitting several revolutions. The parts 25 and 26 are so located and dimensioned as to permit of restarting in the initial direction of operation almost immediately after reversal takes place. An adjustable stop 23 locates the extreme non-effective positions of lever 16 and sleeve 21. The members may be duplicated to provide over-lowering prevention as well, two cams 11 being provided of which the second is made adjustable to vary the range of hoist. The non-effective part of the cam 11 is omitted in this form, and one roller 14 only is provided, the two levers 28 being coupled together.