GB543395A - Improvements in master clock mechanisms - Google Patents

Abstract

543,395. Electric clocks. SMITH & SONS (MOTOR ACCESSORIES), Ltd., S., and RUSSELL, V. J. S. Aug. 21, 1940. No. 13312. [Class 139] A master clock mechanism comprises an A.C. synchronous motor, a time-keeping device for connection with a D.C. source, an impulse-forming device arranged to operate one or more secondary movements and a change-over switch for effecting operation of the impulse-forming device either by the synchronous motor or, on failure of the A.C. source, by the D.C. source under the control of time-keeping device. The A.C. source 31 through a transformer 14, drives a synchronous motor which drives a rotary cam 7 so as to perform one revolution per minute. The impulseforming device 2 comprises a rocking mercury switch 39 having a pair of contacts 6 which are closed by the rotary cam 7 twice in a revolution so that, in circuit with a battery 22, a succession of impulses are provided for operating the secondary movements 21 and if desired, through a second cam and a second mercury switch 35, the time recorders 37. The A.C. source also keeps the battery 22 charged through a rectifier 13 and the battery 22 is arranged to drive continuously a clock pendulum 10. In failure of the A.C. source the relay 4 is de-energized and by means of the mercury switch 32 opens the contacts 18 and closes the contacts 5. The swing of the pendulum 10 of the time-keeping device or clock is maintained in known manner by contacts 11, 23 closing when necessary the circuit of an electromagnet 17 to give an impulse to the pendulum 10. The pendulum 10 controls, magnetically, the contacts 12, 29 to operate an electromagnet 9 to drive the cam 7 through a stand-by step-by-step D.C. motor 3 comprising a ratchet wheel 8 and pawl 16 and the cam 7, as before, in conjunction with the contacts 6 gives the required impulses to the secondary movements 21, &c. Manually operated retarding switches 41, 42 and advancing switches 43, 44 are provided.