GB528790A - Improvements in or relating to electric selective signal-responsive devices - Google Patents

Abstract

528,790. Electric signalling systems. STANDARD TELEPHONES & CABLES, Ltd., and BOWSHER, A. H. March 31, 1939, No. 10112. [Class 40 (i)] Selector mechanism responsive solely to a pair of impulses of predetermined spacing comprises a carrier which executes a cycle of movement, e.g. one revolution, on receipt of the first impulse, an actuating member pivoted on the carrier and held inoperative by a spring until deflected by the second impulse and a variably positioned displaceable member in the path of movement of the actuating member engaged by the actuating member if the interval between the impulses corresponds with the positioning of the displaceable member. In the circuit an arrangement shown in Fig. 4, D.C. impulses over power line LN operate magnet M over transformer Tr so that the magnet does not respond to power A.C. In response to the first impulses, the magnet closes contact C1 to start a motor which drives the selector Sc the motor circuit being maintained over off-normal contacts ONS for one revolution. The selector under the control of the second impulse closes a main switch MC to switch in the load LD. The selector, Figs. 1 and 2, comprises a shaft SP driven by the motor and carrying loosely an oval switch plate P1 controlling a bell-crank BC operating the main switch MC, the plate being normally prevented from rotating by a latch bar LB engaging one or other of the spring controlled levers L1, L2 which project through spaces between fixed projections J. The shaft SP when rotated counterclockwise winds up a spring MS which has a slipping engagement with the pins on the plate P1 to prevent over-winding. A gear wheel G fixed to the shaft engages a planet pinion W mounted on a disc D1 loose on the shaft and urged in the clockwise direction by spring LS so that an actuating member H on the planet lies substantially in the position shown. As explained above, the motor is started by the first impulse and the shaft rotates for one revolution. The second impulse causes magnet M to apply a brake B to disc D1 whereupon the planet W rotates clockwise and member H, passing between the pair of projections J opposite to it at the time of the impulse, swings round in the counter-clockwise direction and clicks over the 'remaining projection J. If a lever L1 or L2 is located in the gap between the projections J entered by the member H, the lever is released from the latch bar LB and the oval cam P1 is rotated by spring MS to operate the bell-crank BC. The levers L1, L2 control on and off switching respectively. In a modification, Figs. 5 to 7 (not shown), in which the projections J and sun and planet gear are dispensed with, the actuating member H is carried by a plate rotating with the spindle and is released by a spring controlled member held until the arrival of the second impulse whereupon it flies around and engages the member H to swing it into engagement with one of the levers if the impulse arrives at the predetermined time interval. Specification 495,057 is referred to.