GB437593A - Improvements in time keeping mechanism, more especially for clocks - Google Patents

Abstract

437,593. Electric clocks. DORER, P. O., 219, Dollis Hill Lane, Cricklewood, London. March 24, 1934, No. 9309. [Class 139] In a clock normally driven by a synchronous electric motor and in which a spring driven auxiliary mechanism takes over the drive when the current fails, the auxiliary mechanism is controlled by an escapement, for example, as shown in Specifications 220,601, 225,522, [both in Class 106 (iii)], which oscillates very rapidly and starts readily directly it is freed. The synchronous motor 10 drives through gearing 11 a wheel 12 loose on the time indicating or controlling shaft 13, and winds up the spring- 14 of the auxiliary mechanism through gearing 19, overwinding being prevented by the spring slipping in the barrel. The wheel 12 is rigid with a freely mounted ratchet wheel 23 coacting with a detent 25 pivoted to a plate 24 rigid with the time shaft 13. The spring 14 is connected through gearing 15 to a pinion 16 loose on shaft 13 and through gearing 17 to the escapement 18 normally locked by an arm 22 rigid with the armature 21 of an electromagnet 20 energized with the motor 10. A friction disc 28 is loosely mounted between the wheels 12, 23, a recess 27 therein coacting with an arm 26 of the detent 25. Normally, the drag on the disc 28 forces the detent 25 into engagement with the teeth of ratchet wheel 23 and the time shaft 13 is driven through 12, 23, 25, 24. When the current supply fails, the auxiliary mechanism is released and the pinion 16 drives the time shaft 13 through a friction disc 29 against which it is pressed by a spring 30, the detent 25 being released from engagement with the ratchet wheel 23. The time shaft 13 may drive normal clock hands or other indicating devices, or may operate electric contacts to control other devices, as in the case of a master clock. In the latter case, the spindle 13 is rotated at, for example, once per minute, and actuates the contacts directly. Modifications. Alternative two-way means for driving the time shaft respectively by the electric motor and by the auxiliary mechanism may be used. The escapement may be locked by means operated directly by the magnetic field of the motor. Reference has been directed by the Comptroller to British Specifications 125,766, [Class 139], 389,406, and 389,908, and to U.S.A. Specification 1,912,650.