GB1462624A - Time switch - Google Patents

Abstract

1462624 Time switches UNITED GAS INDUSTRIES Ltd 6 March 1974 [23 March 1973] 14027/73 Heading H1N A programme switching device comprises a timing drive connected to rotate two or more rotatable cams for operating respective switch means the driving connection allowing each cam to be manually advanced independently of the other cam or cams so as to advance, for a period of time, the operation of the respective switch means, the advanced cam or cams being disconnected from the timing drive during the advance period. Preferably each cam has a thumbwheel for manual advancement, and the driving connection preferably comprises a member with a shoulder which engages in an arcuate cut-out in the cam, said cut-out being of greater angular extend than said shoulder thereby allowing lost motion movement of said cam in advance of the shoulder, the cam then remaining stationary until the shoulder "catches up" and normal timed operation is automatically resumed. As shown, a synchronous motor 13 drives a time dial 15 carrying four adjustable tappets 16 each having a depending leg 17 to step an actuator 19 through 45 degrees. Actuator 19 is rigidly secured on one end of a spindle 22 which carries two pairs of cams 28, 29, each pair being integral with a respective thumbwheel 30 and actuating two respective microswitches 31, 32 (and 34, 35, Fig. 2, not shown). Resilient arms (44, Fig. 2, not shown) locate the eight positions of the cams. The shaft 22 may have a shoulder (40, Fig. 7, not shown) engaged in arcuate cut-out (41) to provide the lost-motion drive, or a washer (50, Fig. 11, not shown) mating on a flat on shaft 22 and having two arms (51, 52) may constitute shoulders which engage end wall (53) of an indented "cutout" in the associated cam. Neon lights 38, 39 indicate when respective circuits are operative.