Patent GB-612611-A (GB)
Title: Improvements in or relating to electric master and secondary clock systems
IPC: G04C13/04
Filed: 1945-09-19
Abstract: 612,611. Electric clocks. LANDIS & GYR SOC. ANON. Sept. 19, 1945, No. 24240. Convention date, Sept. 19, 1944. [Class 139] In an electric master and secondary clock system, control means are provided whereby, when the hands of the master clock are manually set forward or back or when there has been a current failure in the circuit of the secondary clocks, the secondary clocks are subsequently automatically brought into agreement with the master clock. The hands 7, 10 of the master clock are driven through gearing from the spring driving means 1. A differential shaft 11 driven on the one hand by the spring driving means 1 carries a disc 12 and rotates it at a speed of one revolution in thirty minutes. Behind the disc 12 is a second disc 14 which is rotated once in twelve hours. The differential shaft 11 is driven on the other hand as described later from a shaft 25 driven by spring means 26 and carrying a double armed lever 27, one end of which normally bears on a segment 28 which is normally urged by a spring 30 so that a pin 29 engages recesses 13, 15 in the discs 12, 14 respectively. The speed of rotation of the shaft 25 is controlled by a brake disc device 32, 33 and the shaft carries at its outer end an eccentric 34 which co-operates with a wire spring 35 mounted on a pin 36 of a crank 37. The pin 36 projects between two springs 38, 39 of a switch having the limbs 41, 40 and 42 and inserted in the circuit to the secondary clocks 44 from a battery 43. A relay coil 45 is also connected to the spring limbs 40, 42 and when energized holds its armature 46 in such a position that the detent 48 on the arm 47 is out of the path of movement 52 of the ends of the lever 27. An indicating lever 53 constantly engages a pin on the segment 28. In normal operation, the discs 12, 14 are rotated in the direction of the arrow 62, by the spring driving means 1, and the segment 28 is rocked clockwise so freeing the lever 27. The spring driving means 26 then rotates the shaft 25 in the direction of the arrow 52 until the second arm of the lever 27 is arrested by the segment 28 which has been returned to its initial position by the return movement of the discs 12, 14, also by the spring driving means 26. During this time the eccentric 34 through the crank 37, the pin 36 operates the switch to send an impulse to the secondary clocks 44. The operation continues and in the next half-revolution of the lever 27 the eccentric 34, the crank 37 and the pin 36 operates the switch to send another impulse, this time of opposite polarity, to the secondary clocks 44. If the hands 7, 10 are set forwardly by the knobs 59 through the clutch 61, the discs 12 and 14 are moved again in the direction of the arrow 62, the segment 28 is rotated clockwise and the pin 29 rests on the rim of the discs 12, 14. The spring driving means 26 then rotates the shaft 25 and the discs 12, 14 in the return direction and consequently impulses are transmitted in succession to the secondary clocks until the lever 27 is again arrested by the segment 28, at which time the secondary clocks 44 once again agree with the master clock. If the hands 7, 10 are set back, the segment 28 is rocked counterclockwise and arrest the lever 27, so preventing impulses from going to the secondary clocks until the discs 14 and 12 bring the segment 28 back to its initial position and the clocks are in agreement. The lever 53 is provided with " + " and " - " signs to indicate the position of the segment 28. The action after a failure in the circuit of the secondaries is similar to that produced by the setting forward of the hands 7, 10 as the discs 12, 14 are continuously driven in the direction of the arrow 62 during the failure, while the lever 27 is arrested by the detent 48 on the arm 47 of the armature 46. The end 56 of the arm 47 serves as an indication of current failure. In another embodiment, not shown, two switching means, two double armed levers and a backward and forward switching relay, are provided so that the secondary clocks may be set backward as well as forward to come into agreement with the master clock.