Patent GB-380444-A (GB)
Title: Improvements in or relating to control systems for electric elevators
IPC: B66B1/48
Filed: 1931-06-11
Abstract: 380,444. Operating and locking lift cages and doors. SEEGER, E. W., 12th Street, Milwaukee, Wisconsin, U.S.A. June 11, 1931, No. 17029. Convention date, June 13, 1930. [Classes 78 (ii) and 78 (iiil.] Electric plant.-When an electric lift approaches a selected landing, a sliding-contact selector actuates an electro-responsive device to slow-down the lift and a cam device actuates a switch located at the landing so as to stop the lift. The drawings show the invention applied to a lift installation having three landings, the lift being at the second landing. The selector 19, Fig. 2, comprises a drum 30 which is driven at a reduced speed by the lift motor M or otherwise operated at a speed proportional to that of the lift and is provided with contact segments 31, 32, which co-operate with stationary contacts 33 .. 37 to commutate circuits controlling " up " and " down " lift relays 17, 18. The lift is controlled either by buttons 22<1>, 23, 24 therein or by buttons 25, 26, 27 at the landings, precedence being given to the lift buttons as opposed to the landing buttons and to the upper landing buttons as opposed to the lower. If a person in the lift at the second landing desires to descend to the bottom landing, the pushbutton 24 is depressed thereby establishing a circuit from the line L1 through pushbutton 38, contacts 11d, 9d, of reversing switches 9, 11, Figs. 1, 2, contacts 24b, winding 20a of relay 20, contact 33, segment 31, contact 37, winding 18a of relay 18, contacts 17c of relay 17 and protective switches 60, 61, 62, to line L2. On response of relay 18 a motor M1, Figs. 2 and 3, is connected across the lines L1, L2, by the contacts 18b and through an arm 56 and rope 57 retracts a cam 51 secured on the lift by toggles 52. A weighted arm 49a of a lever 49, Fig. 4, pivoted at 46 in a casing 42 on the landing and previously supported by the cam, falls and closes a door switch DS2 by a contact 41 bridging contacts 40, 40, so as to energize a relay 16. A hook 47 simultaneously engages an opening 48 in a bolt 44 to lock the landing door in the closed position. The reversing switches 11, 12, Fig. 1, and the field switch 14 respond on closure of the relays 16, 18, closure of the switches 11, 12, connecting the armature A and the series field F across the lines L1, L2, through resistances R1 .. R4 and energising a coil B<1> to release a brake B, and closure of switch 14 excluding a resistance R5 from the shunt field circuit. The circuit from the line L1 to the button 24 is interrupted by the contacts 11d but the relays 20, 18 are maintained energized by a circuit from the line L1 through a button 38, contacts 16b, relay 20 and its winding 20a, contacts 33, 31, 37, and winding 18a to the line L2. A circuit for a braking switch 15 is also established from the line L1 on response of the switch 11 through contacts 18b, 11c, winding 15a and protective devices 60, 61, 62, to the line L2 and. response of the switch 15 establishes a circuit for an accelerator 13 from the line L1, through contacts 15b, winding 13a to the line L2 whereby the resistances R1 .. R4 and the field F are cut out. The coil B<1> is excluded from the armature circuit on the last accelerating step, the brake B being held released by a coil B<2>. During the descent of the lift the selector 19 rotates counterclockwise and prior to the arrival of the lift at the bottom landing the segment 31 disengages the contact 33 and interrupts the maintaining circuit for the relay 18 so as to open the circuit for the switch 15 and the winding 13a. The accelerator 13 then returns to its normal position and effects slowdown of the motor M. The return of relay 18 de-energizes the motor M1 and the cam 51 is projected by a spring 54. During final movement of the lift into a position opposite the landing, the cam 51 actuates the lever 49 so as to open the switch DS1 and interrupt the circuit of the relay 16, and the switches 11, 12, 14, the motor M then being stopped by the brake B. A lever 43a, pivoted on the casing 42, prevents the lever 49 returning to the doorlocking and switch-closing position except when the door is closed.