GB420490A - Improvements in safety devices for moving stairways - Google Patents

Abstract

420,490. Escalators. WAYGOODOTIS, Ltd., 54, Fetter Lane, London. Oct. 26, 1933, No. 17618/34. Convention date, Feb. 10, 1933. Divided out of 419,334. [Class 78 (i)] [See also Group XXXVII] The control system for the driving motor 70 described in Specification 419,334, is modified by the inclusion of a dynamic brake switch J and an auxiliary dynamic brake switch JJ. The operation of the switch J renders effective the dynamic braking resistance 106 so that the motor is caused to act as a dynamic brake to assist in stopping the escalator, this action continuing as long as the speed of the motor armature is such, in conjunction with the strengthened motor field, created by the return of the field to initial position, as to induce in the motor armature 90 a voltage sufficient to maintain operated the switch JJ. The switch J is actuated when the brake switch H is returned to the off position by the operation of either the carriage switch 101, handrail switch 63 or 102, or governor contacts 72. The operation of these safety devices causes also the immediate dropping out of the up direction switch A, and the application of motor brake 91 and escalator brakes 92 and 93. The application of the latter brakes is relatively hard. Since it is undesirable always to stop the escalator quickly, provision is made by which normal stops, such as those obtained by pressing a button 107 are made less quickly. When the button 107 is pressed, the potential switch C opens, thus causing the de-energization of the motor 70 and the application of the brakes 91, 92, 93. Since the resistance 104 is rendered effective by the closing of the contacts 105, the application of the brakes 92, 93, is relatively soft. The motor is not used as a dynamic brake since the switch J cannot be energized while the switch C is open.