Patent GB-144795-A (GB)
Title: Improvements relating to loading and unloading gear for hoisting plant and the like
IPC: B66B17/20
Filed: 1919-03-17
Abstract: 144,795. McKenzie, Holland, & Westinghouse Power Signal Co., and Castleman, F. M. March 17, 1919. Axle stops.-Each deck of the hoist 3 and cage 1 and the upper deck of the hoist 2 is provided with stops 33, 34, 12, 13, 42, respectively, having indication contact devices 35, 36, 14, 15, 43, each comprising a pair of switches which are closed automatically when the stops are in position to prevent backward movement of the tubs. Each deck of each hoist and the cage is provided with an axle counting device and stop 27, 28, 16, 17, 40, 41 which is locked automatically after a predetermined number of tubs has passed. Each counting-device is provided with an unlocking- device such as 18 having an indication contact 20 comprising a number of switches. The deck 38 of the hoist 2 has a mechanically-actuated axle stop 44. An axle counter 48 is provided on the track 47 and closes one pair of switch contacts when six axles have passed, and another pair of contacts when a further six axles have passed. The electric circuits through which the apparatus is actuated are controlled by switches 63 - - 68 mounted on a shaft 62 which also carries interlocking members 69, 70 provided with release magnets 71, 72. The shaft 62 is rocked by a lever 61 which cannot be moved from the position C to the positions R, N until the magnets 71, 72, respectively, are energized. When the lever is at N, the switches 63, 64, 68 are closed; at C, the switches 64, 65, 66 are closed; and at R the switches 65, 66, 67 are closed. When one cycle of operations has been completed, the cage 1 is ready for lowering, the lever 61 is at N, and two circuits are completed. The first circuit runs from the positive terminal 77 through upper indication switches 15, 14, right-hand indication switches 21, 20, the switch of the axle counter 40, lower indication switch 43, the switch of the axle counter 41 to the point 78 where it branches into parallel circuits, one leading to negative terminals 80, 81, and the other circuit leading to the negative terminal 82. The completion of this circuit gives the indication " All clear to lower " on the indicator A. The second circuit runs from the positive terminal 83 to the negative terminal 107 through the switch 68 and relay winding 73, the two armatures of which are thus held in the closed position. The cage is now lowered, refilled with full tubs, and raised. On reaching the surface, the indication contact 23 is closed, and when the lever 61 is moved to the position C, a circuit is completed from the positive terminal 84 through conductor 85, switch 65, to the negative terminal 82. A circuit is completed also from the conductor 87, conductor 89, lower armature relay 73, switch 66, the actuating-magnets of the four axle-counter unlocking motors 18, 19, 29, 30 to the negative terminals 90. When the lever 61 is moved to posi. tion C, the original energizing-circuit for the relay 73 is broken at the switch 63, but a maintaining circuit is provided from the positive ter. minal 91 to the negative terminal 107 through the lower indication switches 14, 15, upper armature relay 73, and the winding of the relay. When the axle counters 16, 17, 27, 28 have been unlocked, the corresponding indication contacts 20, 21, 31, 32 are closed, and a branch circuit is completed from the lower armature of the relay 73 through the conductor 92, left-hand indication switch 31, conductor 93, left-hand indication switch 20, conductor 94, middle indication switch 32, conductor 95, left-hand indication switch 21, indicator D to the negative terminal 96, and through the magnet 71 to the negative terminal 97. The indicator D now displays the signal " Ready to ram," and the lever 61 is free to take up the position R in which position a circuit is completed from the positive terminal 83 through the switch 67 and conductor 98 to the point 99 where it branches to the conductors 100, 101 leading to the negative terminals 102. The passage of the tub axles over the indication contacts 14, 15 has caused the relay 73 to be deenergized and its armatures to move to open position, but as soon as the total number of axles has passed over the counters, the counters 40, 41 re-establish the indication circuits and the axle counters are again locked automatically. The lever 61 may now be moved back to position C in which the circuit through the switch 64 is completed. The lever 61 can now be put back to position N and the cage lowered. The hoist 2 is lowered from the position shown to the position in which the deck 38 is level with the track 47 when a circuit is completed, which includes the valve-actuating magnet 50 of the fluid-pressure lowering-device 49. This circuit is completed when the axle counter 40 and indication contact 43 are closed by the passage of the tubs from. the deck 4 to the deck 38, the axle counter 48 is in one of its two closed positions after the tubs on deck 39 have passed on to the track 47, and the indication contact 46 is closed.