Patent GB-190819458-A (GB)
Title: Improvements in Electrically Driven Turret Clocks.
Filed: 1908-09-16
Granted: 1909-09-16
Abstract: 19,458. Newitt, E. J. D., Webber, A. B., and Standard Time Co. Sept. 16. Electric clocks.-Relates to means for locking the hands of electric turret-clocks against external influences, and also to means for synchronizing such clocks. An electrically-maintained pendulum a drives a ratchet-wheel c in the usual manner through a claw b, and the motion of the wheel c is communicated to a spindle k<3>, connected to the clock-hands, by means of the epicyclic train shown in Fig. 2 ; this mechanism is non-reversible, and effects a high reduction in speed. The pinion j, carried by an arm i which revolves with the ratchetwheel c, gears simultaneously with spur-wheels k<1>, k', the wheel k<1> being fixed, and the wheel k' being connected to the spindle k<3>. This spindle consequently cannot be rotated diractly by the action of wind &c. on the hands. The clock is synchronized with a standard clock, by giving it a slight gaining rate, and, by the action of a current transmitted from the controlling clock, periodically disengaging the driving-claw b from the ratchet c sufficiently long to correct the error. The leads m<1>, m', Fig. 1, carrying the synchronizing- current, are normally short-circuited by springs o<1>, o<2>, which are held in contact with each other by a disk o<3> carried by the minute arbor of the clock. When the end of the spring o' drops into the notch o<4> of the disk, the synchronizing-current energizes the magnet n causing the lever n<2> to lift the claw b, thereby stopping the clock until the current ceases at the proper instant. If the synchronizing-circuit is accidently traversed by an extraneous current, the circuit is automatically broken by means of the device shown in Fig. 4. This comprises an electro - magnet p in the synchronizing-circuit, the magnet having an armature q which bears a pin q<1> adapted to press against a spring r' when the armature is fully attracted, whereupon a bridge-piece s along which the current is flowing, drops from its supports r<1>, r<2>, and breaks the circuit. The movement of the armature q is delayed by an escapement, so that only a prolonged current will draw the armature into the position at which the bridge s drops, a normal synchronizing- current being of insufficient duration. The delaydevice comprises a sector t, adapted to gear with a pinion u on the arbor of a scape-wheel v controlled by a pendulum, and connected by a link q<3> to the armature. To permit a quick return of the armature q by means of a spring q<2>, the sector t is mounted on a pivoted arm t<1>, so that a downward movement of the armature draws the sector into gear with the pinion u, the arm t' resting against a stop t<3>; the upward return motion raises the arm t<1> and throws the sector out of gear. When the clock is synchronized only after long intervals, the current initiates the stopping of the clock through a relay circuit, which is kept energized for the required period by means of a delay-device similar to that described above, but in which the armature has a free approach and a delayed return. In the Provisional Specification, Specification No. 12,999, A.D. 1905, is referred to ; and the use of worm gearing between the pendulum and the hands o<-> the clock is described.