Patent GB-674733-A (GB)
Title: Improvements in or relating to a secondary clock mechanism
IPC: G04C11/00
Filed: 1949-05-16
Abstract: 674,733. Electric clocks. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 16, 1949 [July 9, 1948], No. 12976/49. Class 139 A secondary clock mechanism of the type having a series of' time indicating drumlike elements comprises a rotatable seconds member (disc 102), a rotatable units minutes member (gear 92), means normally rotating said seconds member continuously and uniformly at its normal time-keeping rate of one r.p.m., and Geneva driving gear mechanism operatively connecting said members whereby continuous rotation of the seconds member causes intermittent rotation of the units minutes member, a rotatable member (disc 100), clutch means for connecting, said rotatable member and seconds member in driving relationship for causing the former to rotate at the speed of the latter, a latch member normally rendering said clutch means inoperative, means for tripping said latch member to permit said clutch means to become operative, said last mentioned means comprising an electromagnet responsive to the reception of a signal, and coupling means between said rotatable member and units minutes member operable when the latter is at a chronological position slower than standard time. The " seconds drum 45, is operative for driving said units minutes member uniformly at the rate of said rotatable member for an angular distance sufficient to advance the units minutes member to a chronological position coincident with standard time and when said clutch means Figs. 1 and 5, is normally rotatable at one revolution per minute by an electric motor M through a gear 66, a gear 68 on a drive shaft 70, a gear 72, Fig. 5, an idler gear 74, a gear 78 fixed to a correction shaft 80 rotating at 1 rev/min., and a driving gear 52 frictionally coupled to the drum 45. The units minutes drum 42 is stepped-on by a Geneva mechanism 57, 59, from the drum 45. The hours, and tens of, minutes drums 40, 44 are also stepped on by Geneva mechanism. The gear 57 also meshes with a gear 98 on a shaft 96 which carries a gear 94 which normally drives a gear 92 loose on the shaft 80 in sychronism with the drum 42. Loosely mounted co-axially with the gear 92 is a normally stationary correction disc 100. Secured to the shaft 80 is a toothed disc 102 (the seconds member). A clutch piece 106 is pivoted to the disc 100 which is normally retained by a pivoted latch member 114 in such a position that its laterally extending tooth 122 is out of engagement with the toothed disc 102. When, at the reception of a synchronizing signal, as described in Specification 674,721, the latch member 114, Fig. 4, is swung anticlockwise, the clutch piece 106 is moved by a spring 110 and its tooth 122 engages the teeth of the disc 102 whereupon the disc 102 is rotated one revolution in one minute. Secured to the disc 100 is a spring piece 124 which includes an arm 128 and an inwardly extending part 130 which projects through an opening in the disc and supports the spring 110. The arm 128 is bent outwardly at its end 140, which normally touches the adjacent face of the gear 92. During the revolution of the disc 100, however, if the clock is slow the end 140 of the spring piece enters a recess 138 in the gear 92 which is thereby rotated for the remainder of the revolution with the disc 100. The movement of the gear 92 is transmitted via gears 94, 98 and 57 to the drum 45. The disc 100 has a notch 200, Fig. 6, in which a roller 202 carried by a lever 204 normally rests to retain a spring stop 214 carried by a block 208 out of the path of the Geneva tooth 59. During rotation of the disc 100, however, the roller 202 is moved and the spring stop comes into the path of the Geneva tooth 59 and the drum 45 is arrested at the "59 seconds" position until the disc 100 completes its revolution and the roller 212 again engages the notch 200.