GB891660A - Improvements in or relating to moving stairways - Google Patents

Abstract

891,660. Escalators. WESTINGHOUSE ELECTRIC CORPORATION. Sept. 21, 1959 [Sept. 26, 1958], No. 32017/59. Class 78 (1). Chains 3, 4 driving the steps 1 of an escalator on rollers 19, 22 pass round tensioning idler sprockets 8, 9 mounted on a common axle 31 supported on a horizontally movable carriage 41 which is spring-urged to tension the chains and which is guided to prevent its rotation about a vertical axis. Bearings 44L, 44R, supporting the axle 31, are secured to the legs 42L, 42R respectively of a yoke 41 provided with a tongue 47 which is guided between rollers 65, the legs 42L, 42R and the guide tongue 47 being supported on rollers 52L, 52R and 55 on tracks 57L, 57R and 59 respectively which are channelled to prevent horizontal movement of the rollers in a direction parallel to the axle 31. A spring 71, mounted on a rod 73 secured to the yoke 41, is compressed between a fixed plate 75, through which the rod 73 passes, and a washer 77, retained on the rod by means of nuts 78, and urges the yoke and sprockets to the right to tension the chains. A safety switch for stopping the drive motor and applying a motor brake when the yoke and sprockets 8, 9 move through a predetermined distance comprises a fixed contact 87 and a contact 85 on one end of an arm 93 pivoted at 95, the other end of the arm being located in a recess 101 in the yoke leg 42L and normally retained in the vertical position shown, Fig. 3, by means of a spring 97. Thus, if the yoke moves through more than a predetermined distance, an edge of the recess 101 will engage the arm 93 which will pivot to separate the contacts 85, 87.