Patent GB-470562-A (GB)
Title: Improvements in or relating to clock mechanisms
IPC: G04C3/02
Filed: 1935-11-13
Abstract: 470,562. Electric clocks. SMITH, S. J., and TELEPHONE MANUFACTURING CO., Ltd. Nov. 13, 1935, No. 31446. [Class 139] A clock mechanism having a pendulum or balance employed, for example, to actuate mechanism for producing intermittent electrical impulses for operating slave clocks, time recorders and the like, has electromagnetic means for energizing the pendulum, the circuit for which includes contacts actuated by an abutment on the pendulum which engages a contact-making element only at an amplitude greater than the amplitude at which it is released from the element. The clock has (1) means for normally driving the time train-parts 19, 20, 21, 26, 28, 30 ; (2) means for closing an external circuit 44 (for secondary clocks) every half minute-parts 38, 41, 42 ; (3) means 45 for advancing or stopping the secondary clocks ; (4) means 47-50 to re-energize the pendulum 14 as its oscillations die down ; (5) means 56, 62, 60 as described in Specification 470,586 to synchronize the pendulum 14 with a synchronous electric motor 57 ; or (6) means 56, 64 to synchronize the pendulum 14 with a second and free pendulum 58. (1) A halfseconds pendulum 14 suspended at 15 is embraced by a pair of arms 16 on a strip 17 parallel to the pendulum. A plate 19 fixed to plate 17 has a roller 20 coacting with the offset end of a bell-crank 21, 26 of which the forked end 26 rocks a hemispherical piece 28 on a spring strip 27. As the pendulum swings right and left respectively, Fig. 1, the roller 20 depresses and raises the offset end of arm 21 so that the piece 28 is moved left and right respectively to engage and move the teeth of wheels 29, 30 which mesh with one another. Wheel 30 serves as the first wheel of a time train and also rotates a hand 33 over a pilot dial 34. (2) A disc 31 driven bv wheel 30 rotates once in half a minute and has a notch 39 coacting with the pawl 38 of a lever 41 pivoted at 40. An arm 42 on plate 19 normally oscillates freely, but when lever 41 is lowered by pawl 38 entering notch 39, the arm 42 rides up the lever 41 and closes contacts 44 for the secondary clock circuit. (3) In the position of lever 45 shown in Fig. 1, the operation is as in (2) above, but if lever 45 is moved to the "run up" position it lifts the arm 42 at each swing of the pendulum to close the contacts 44. If arm 45 is moved further to the " stop " position, the arm 42 is moved at each swing to a position where it can in no circumstances close the contacts 44. (4) The pendulum 14 is maintained by magnet 47 as follows : as the pendulum swings left, an offset 46, Fig. 3, on an arm pivoted to the pendulum passes freely beneath a catch 53. As the pendulum returns to the right, the righthand end of arm 46 engages the lower edge of cam 21 as the latter is depressed by roller 20 and the left-hand end of arm 46 passes across the upper surface of catch 53 and just beyond it. If the swing of the pendulum dies down, however, the offset of arm 46 does not clear the catch 53 and on the return to the left the catch is depressed to close contacts 51 which energize the magnet 47. The arm 46 continues clear of the catch 53, whereby armature 48 and its roller 49 are raised and then lowered, the roller 49 giving an impulse to a piece 50 on the plate 19. (5) The synchronous electric motor 57 rotates a cam 58, Figs. 1 and 8, which oscillates a lever 60, pivoted at 61, once every half minute-or once for every swing of the pendulum if desired. A pair of pallets 62, pivoted to the lever 60 and having serrated lower faces, are thus periodically lowered on to a blade 56 on the plate 17 swinging with the pendulum 14. There is a slight gap between these pallets and if the pendulum and arm 60 are in synchronism, the blade will enter the gap as shown in Fig. 8. If the pendulum is fast or slow, the blade will meet the serrated face of one or other of the pallets 62 so that the pendulum is retarded or given a slight impulse. (6) In a modification, Fig. 11, the master timing device is a long free pendulum 58 in place of the synchronous motor. Preferably, for a half-seconds pendulum 14, the pendulum 58 is a one-second pendulum. Blade 56 on pendulum 14 coacts with a rack 64 pivoted on two knife edges 164, 165 and held clockwise by a weight 65. Once each half minute the arm 42 on the pendulum 14 removes a latch 68 from a lever 71 carrying a roller 66 which, in falling, gives an impulse to the piece 69 on pendulum 58. At the same time, extension 70 of arm 71 depresses rack 64 about its left-hand pivot to meet the blade 56 as pendulum 14 swings left. Pendulum 14 is arranged to lose slightly if allowed to swing freely. When blade 56 meets rack 64 the latter is tipped about its right-hand pivot 165 and the swing of pendulum 14 is slightly reduced, whereby it gains.