Patent GB-397388-A (GB)
Title: Press button control for elevators and the like
IPC: B66B1/16
Filed: 1933-02-20
Abstract: 397,388. Control of motors. HOFFMANN, T., 41, Genfer Strasse, Reinickendorf, Berlin. Feb. 20, 1933, No. 5211. Convention date, Feb. 25, 1932. [Class 38 (iii).] Travelling to predetermined limits.--A pressbutton control for lifts is characterized in that the resistances which lie between the press-buttons connected in parallel form one variable branch of a resistance bridge by the changing of which equilibrium is destroyed, so that a motor or progressive switch relay connected in the bridge receives' current and changes the second variable resistance bridge until equilibrium is established. The motor is stopped and the position of a contact arm is made to correspond to that of the actuated press-button. A bridge resistance 7-8 is connected to a supply main 28, and 9-10 represents a resistance in a cage 11 variable by press-buttons 12 for different stops. 13-14 represents the other bridge branch which is changed by a contact bar 15 and arm 16 actuated by a motor 17 through gearing (not shown). The motor is placed between points 18-19 of the bridge. In the resistance 9-10 is varied by a press-button 12 the motor will run and operate the arm 16 until the resistance 13-14 equals that at 9-10. Individual stopping places are controlled on a second contact arrangement 20-21 running in synchronism with that of 15-16. Wires corresponding to the stopping places extend from the contact 21 to the storey switches 22 arranged in the lift shaft and actuated by the cage or repetition apparatus in the engine room. Two leads corresponding to the upward and downward travel of the cage extend from the storey switches to reversing relays 23 of the elevator motor. A relay 24 is a locking relay in connection with a locking rod sytem (not shown). An auxiliary ,relay 26 serves to lay the main supply voltage 28 on the bridge 7-8 by a contact 27 and also to actuate the locking relay 24 until it receives voltage by contacts 29 or 30 on the reversing relays 23. Assume the cage in the highest position, and the highest of the storey positions in the cutting-out position and contact arms 20, 16 as shown in dotted lines. If a press-button 12 is depressed, which switches in resistance 31-10, current flows from 28 through relay 26, press-button 12 and resistance 31-10 and through resistance 13-14, bar 15 and contact 16 back to main 28. The relay 26 closes contact 27. Thus supply is laid on the point 8 of the bridge 7-8. As the resistance 31-10 is not equal to the resistance 13-14, the motor revolves and moves arms 16, 20 to the positions shown, making the resistances equal and stopping the motor. During the actuation of the press-button 12 relay 26 is under voltage and contact 27 closed, the locking relay 24 receiving voltage. The attraction of the relay 24 is damped to prevent its closing before the motor is stopped. Current flows from the main 28 through the locking contact 25, arm 20, storey switch into the reversing relay for downward travel and back to the main. Contact 30 on the downward relay 23 is closed so that locking relay 24 receives voltage therefrom and press-button in the cage can be released. The cage descends until it opens the storey switch corresponding to the stop. The motor is preferably not directly connected to the points 18, 19, but through a relay.