GB616562A - Improvements in electromagnetic relays - Google Patents

Abstract

616,562. Electric selective signalling systems. GENERAL ELECTRIC CO., Ltd., and SMART, N. C. July 15, 1946, No. 21079. [Class 40 (i)] In a code-responsive switching mechanism of the type described in Specification 546,889, in which operation of a lever by a relay sets a motor in operation, this motor rotating a plurality of cams to close a work contact, and in which the cycle is completed only if the received signals are of correct duration and frequency, the relay operating the lever is of a vibratory tuned reed pattern to render the circuit more selective to the operating frequency, and the lever, when moved off normal, is held there by a magnet until restored by a further motor-driven cam. Referring to the Figure, reception of the correct frequency at coil 2 causes vibration of reed 6 to rotate lever 4 about a pivot 5. An armature 35 at its upper end is brought into proximity with a magnet where it is held, causing pivotal movement of a further lever 36 and closing the circuit of motor 12 through contacts 13. The motor commences to. rotate cams through step-down gearing 11 and a pin wheel through further step-down gearing 25, this pin wheel restoring the levers to their original positions. If the duration and spacing of the code signal is not correct one of levers 20 or 21 engages with one of the projections on code cams 26 and 27 causing reversal of the motor to its original position as described in Specification 546,889. The work contact is shown at 32, and contacts 39 hold the motor circuit closed when contacts 13 part if the motor is away from its zero position.