Patent GB-674721-A (GB)
Title: Improvements in or relating to a one-revolution clutch mechanism and a secondary clock mechanism
IPC: G04C11/06
Filed: 1949-01-07
Abstract: 674,721. Operating clutches. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 7, 1949 [Jan. 30, 1948], No. 474/49. Class 80 (ii). [Also in Group XVIII] A one revolution clutch in a secondary clock comprises a, driving member and a, driven member, clutch means for connecting said members, a latch member normally rendering said clutch means inoperative, means controlled by an electromagnet to trip the latch member, said latter means comprising a trip member movable upon energisation of the electromagnet into engagement with the driving member to be moved thereby to trip the latch member. In the secondary clock the output shaft 26 of the synchronous motor M, Fig. 5, carries a pinion 28 which meshes with an internally toothed member 30 rotatable on the seconds shaft 32. A gear 42 frictionally fixed to the gear 30 and secured to the shaft 32 carries a stop arm 46. Fig. 1, and drives through the gears 48, 52, 54 and a friction ring 56, Fig. 5, a gear 62 secured to the minutes sleeve 64. The hours sleeve 66 is driven through the gear train 68, 70 and 72. The pinion 28 also drives at one revolution per minute, through the gears 80, 82, Fig. 5, a counter shaft 84 to which a large toothed disc 86 is secured. Loosely mounted on the shaft 84 forwardly of the disc 86 'is a disc 90 which carries a pivoted clutch piece 94 biassed clockwise, Fig. 1, by a spring 98 but normally retained by a latch member 102 in such a position that a tooth 108 thereon is out of engagement with the teeth of the disc 86. A notch 110 in the disc 90 is normally engaged by a roller 112 carried by one arm of a pivoted bell-crank lever 114 the other arm of which carries an abutment member 118. The disc 90 carries an irregularly shaped spring member 124 having an arcuate arm 128 and a part 130 which passes through an opening in the disc 90 and to which the spring 98 is fixed. The arm 128 has an outturned end 140 which normally bears against the back of a disc 134 loose on the shaft 84 but which may move into a radial slot 138 in said disc 134 and thereby rotate it. The disc 134 carries a gear 142, Figs. 1 and 5, which meshes with the gear 68 and is normally rotated thereby at one revolution per hour. The arm 46 and the slot 138 should occupy datum positions at the end of every hour if the clock is " on time " and means are provided to set them to these datum positions every hour if necessary. For this purpose the pivoted armature 152, Fig. 1, of an electromagnet 150 carries a restoring weight 172 to the top end of which a trip member 174 is pivoted. The arrangement is such that when, upon energisation, the electromagnet 150 lifts its armature 152 the end 182, Fig. 1, of the trip member 174 is moved into engage- .ment with the teeth of the disc 86 and is thereby moved for the duration of the energising impulse at the end of which it moves the latch member 102 to release the clutch piece 94 the tooth 108 of which then engages the teeth of the disc 86. The disc 90 then rotates through one revolution in a minute. At the start of its rotation the roller 112 is moved out of the notch 110 and the resulting counter-clockwise movement of the bell-crank 114 brings the abutment member 118 into the path of the arm 46 which is thereby arrested in its datum position with the seconds hand 12, Fig. 5, at zero. If the secondary clock is slow the end 140, Fig. 1, of the spring member 124 will, during the rotation of the disc 90, enter the slot 138 and thereby rotate the disc 134 to its datum position with the minute hand 14 at zero. The synchronizing impulses sent to the electromagnet 150 are of approximately three seconds duration and terminate at the fifty-ninth minute after every hour. The clock is thus synchronized on the hour. Transient impulses of less than three seconds duration which reach the electromagnet will be ineffective as the trip member. 174 will not then be moved far enough to effect releasing movement of the latch member 102. A copper cylinder 184 may surround the armature end of the core. of the electromagnet 150 to provide further delay means. Specification 632,685, [Group XVIII], is referred to.