GB1487908A - Timepiece - Google Patents

Abstract

1487908 Watches EBAUCHES SA 25 March 1976 [10 April 1975] 11951/76 Heading G3T In a timepiece having a minute indicator 1 on a cannon pinion 2, and an hour indicator 6 which is adjustable in one hour steps when changing time zones, in order to avoid displacement of the minute hand 1 during such adjustment a locking member 30 is coupled to the adjusting mechanism momentarily to lock the cannon pinion, and a resilient coupling is provided in the drive to the cannon pinion to yield when the pinion is so locked, the coupling acting, when the pinion is released, to move the minute hand to the position it would have occupied if it had not been restrained during the adjustment of the hour hand 1. The resilient coupling yields at a torque below that transmitted by the usual friction clutch (not shown) provided in the drive to the cannon pinion to permit conventional hand setting. As described the coupling comprises an arcuate wire spring 35 with its ends 35a bent at right angles into elongated slots 33, 34 formed respectively in a centre wheel 31, which is freely mounted on the cannon pinion 2, and a disc 32 which is forced on that pinion. The hour hand 6 is attached to a wheel arid arbor 5 with a star 7. The star is coupled to hour wheel 4, which may bear a conventional hour hand, by an annular spring 8 attached to the hour wheel at 9. The star has twelve teeth and the torque needed for it to slip under the spring 8 during adjustment is greater than the yield torque of the resilient coupling. The watch has a stem 10 coupled to a pull-out piece 17 and a lever 13 which is pivoted at 14. With the stem pushed in as shown, a wheel 12 mounted on the lever couples clutch pinion 11 on the stem to a pinion 24. The latter is attached to a shaft 25 which carries a member 28 with two sets of teeth 28b and a cam 29 which acts on one arm of bifurcated locking spring 30. When the stem is turned, the teeth 28b are rotated into intermittent engagement with the wheel 5 to rotate it in one hour steps and, at the same instants, the cam 29 brings teeth 30b on the other arm of the spring 30 into locking engagement with the hour wheel 4. The cannon pinion is thus also locked but the centre wheel 31 continues to rotate, flexing the spring 35. When the stem is released, the spring 30 returns the parts to the position shown and the spring 35 moves the cannon pinion and minute hand to their correct position. If the stem is pulled out to an intermediate position, the wheel 12 is displaced to bring calendar correction toothing 21 thereon into mesh with a date ring 22. When the stem is fully pulled out, the wheel 12 meshes with an idler 23 which meshes with the hour wheel 4 for conventional correction of the hands.