Patent GB-238937-A (GB)
Title: Hoisting engine controls
IPC: B66B5/08
Filed: 1924-05-26
Abstract: 238,937. Lilly, W. J., and Logan, H. H. May 26, 1924. Overwinding and overrunning, preventing, and emergency power cut-off gear. - Comprises mechanism having two cam-bearing members, one for each direction of travel, the movements of which correspond to those of the cage, cams on these members for actuating stopping means at the limits of travel, and a centrifugal governor adapted to open a controlling switch on excessive speed being attained. Different speed limits are set for raising men and material. Two cam discs 10, one for each direction of rotation, are loosely mounted on and driven through gearing 11, 14, 12 from a shaft 8 positively driven from the winding drum. A centrifugal governor 22 acts through a system of floating levers and closes the switch contacts 45 of a warning bell; if the speed still increases it separates switch contacts 35 in a circuit controlling the winding engine and the brakes. This circuit' comprises a solenoid operating a latch holding up a weight 153 on a rockshaft 150 so that when this circuit is broken the weight falls and closes the engine throttle and applies the brakes. As the cage approaches its limits of travel a cam 134 on the disc 110 actuates an alarm bell 128, and another cam 66 operates a lever 63 which acts on the floating lever system and causes the warning switch 45 and the control switch 35 to operate at a lower speed. If the speed has already been reduced by the engineer these switches do not come into action. Finally, a stop cam 61 acts on a roller 60 and lever 59 and opens another switch 53 in the control circuit, thus releasing the weight 153 to close the throttle and apply the brakes. The brakes are applied more gradually during the intermediate stages than near the end stops, this effect being produced bv a wedge 168, Fig. 10, connected to the lever 63 operated by the cam 66. Normally this wedge is in the position shown and limits the fall of the weight 153, but when the cage approaches its limit the wedge is withdrawn bv the cam and the weight has a longer drop. In order that the cage may start away rapidly in spite of the fact that the speed-limiting cam 66 is in action, the effect of this cam is neutralized by another cam 99 acting on a roller 98 controlling the switch 95 of a solenoid 74. A second switch in the solenoid circuit' is closed when the engineer starts the cage in the reverse direction so that this solenoid is energized and raises one of the pivots 88 of the floating lever system, thus overcoming the effect of the retarding cam 66 and permitting a higher speed to be attained without bringing the governor into action. When men are being hoisted a lower speed limit is in use and the retarding and stopping cams act' at an earlier point than when material is being raised. To effect this the engineer raises a rod 108 operating a cam lever 10 which (1) shifts the position of the idle wheel 14 in the gear train driving the cam disc 10 and so displaces the discs forwardly on the shaft 8 causing the cams to act earlier, and (2) acts through a projection 113 on the floating lever system raising one of the pivots 69 and thus ensuring that the governor acts at a lower speed. Signal lamps operated by the movement of the cam lever 110 indicate to the engineer and to the men at the top and bottom of the shaft that the limiting device is in use. The various cams are adjustably secured to the cam discs 10.