Patent GB-773389-A (GB)
Title: Synchronous motor secondary clock
IPC: G04C11/06
Filed: 1955-06-16
Abstract: 773,389. Electric clocks. INTERNATIONAL BUSINESS. MACHINES CORPORATION. June 16, 1955 [Jan. 18, 1954], No. 17381/55. Class 139. A secondary clock is driven from and receives correcting signals over the supply mains. The seconds hand, the seconds and minutes hands and the seconds, minutes and hour hands are corrected by signals of different duration. The main shaft 18 of the motor 17, Fig. 1, drives a seconds hand shaft 21 through a friction clutch comprising a drum 20 on the shaft 18 and a U-shaped spring 25 attached by a stud 27 to a seconds hand correcting cam fixed to the shaft 21. The minute sleeve 22 carrying the minute hand 12 is driven from the shaft 21 via gears 28, 31, 33, 34 and friction clutch 35, 36, the member 36 of which is fixed to the sleeve 22 and constitutes the minutes hand correction cam. The hours sleeve 23 is driven from sleeve 22 via gears 41, 42, 44, 45 and a friction clutch 46, 47, the member 47 of which constitutes the hours hand correction cam. A shaft 53 is driven at a speed of 1 revolution per minute from the shaft 21 via gears 19, 50, 52 and carries a disc 54. Adjacent the disc 54 is a clutch arm 55, Figs. 1 and 4, pivoted to a crank arm 56 secured to a sleeve 58 loose on the shaft 53. A friction member 57 also secured to the sleeve 58 bears against the disc 54 and carries a leaf spring 61, Fig. 3, which normally urges the arm 55 clockwise out of engagement with the disc 54 against a detent 62 carried by a shaft 64. At its other end the sleeve 58 carries a cam 59, Figs. 1 and 4, which co-operates with a roller 71 carried by one arm of a rocker member 70 rigidly secured to a sleeve 73 rotatable on shaft 64 and carrying a seconds correcting arm 74 having a roller 75. The members 70, 74 are normally urged clockwise by a spring 77 with roller 71 against the lowest part of cam 59 and roller 75 spaced from cam 26. Pivoted on sleeve 73 is an arm 81 which is urged clockwise by a spring 84 and which carries a roller 82 in line with but normally spaced from the cam 36. Adjacent the arm 81 the sleeve 73 carries a hook lever 85 which co-operates as described later with a pawl 86 loose on lever 81. Also pivoted on the sleeve 73 is an arm 91 urged clockwise by a spring 94 and which carries a roller 92 in line with but spaced from the hours cam 47. A hook portion 70a of the rocker member 70 coacts as described later with a pawl 96 loosely pivoted to the arm 91. Tripping of the clutch detent 62 is effected by an electromagnet 100 which upon energization by a high frequency signal moves its armature 101, Fig. 3, so that a sector member 106 moves into engagement with the disc 54 and is moved thereby in a counter-clockwise direction until a pin 108 secured thereto moves detent 62 to release the arm 55 and initiate a correction cycle. Upon de-energization of the electromagnet 100 the member 106 is withdrawn from the disc 54 and returns to its initial position. Hand correction. Three seconds before the fourteenth, twenty-ninth and forty-fourth minutes of each hour the electromagnet 100 receives a three second impulse to effect, as described above, release of the clutch arm 55 after three seconds to cause rotation of the sleeve 58 and the cam 59 for one revolution. The roller 71, Fig. 4, follows the cam 59 and the arms 70, 74 are slowly moved counter-clockwise until roller 71 reaches the drop off of cam 59 and the arm 74 is rapidly returned clockwise and the roller advances or retards the cam 26 to its datum position. At the end of its revolution the arm 55 meets the detent 62 and is disengaged from the disc 54 and the arms 70, 74 are returned to their initial positions by spring 77. Three seconds before the fifty-ninth minute of each hour the electromagnet 100 receives a six seconds impulse. While the electromagnet is energized a lever 110, Fig. 4, attached to the armature retains the pawl 86 in position to be engaged by the hook 85 on the sleeve 73 so that the minutes correcting arm 81 is moved with the seconds correcting arm. The seconds hand is corrected as previously described and the roller 82 on the arm 81 will correctly locate the cam 36 attached to the minutes sleeve. Three seconds before the fifty-ninth minute which precedes every twelfth hour the electromagnet 100 receives a nine seconds impulse so that the pawls 86 and 96 are held in position by the lever 110 to be engaged successively by the hook levers 85 and 70a respectively so that during the correction cycle the hour correcting arm 91 will be moved with the arms 74, 81. The arms 74, 81 will effect seconds and minutes hand correction as before and the roller 92 will correctly locate the cam 47 attached to the hours sleeve. Each cam 26, 36, 47 has a slot 114 to provide a resilient lobe. Specification 674,721 is referred to.