GB1412340A - Chronograph timepiece - Google Patents

Abstract

1412340 Chronographs EBAUCHES SA 7 March 1973 [15 March 1972] 10999/73 Heading G3T A chronograph gear train may be disconnected from the timepiece train, by which it is normally driven, by means of a clutch, both ends of the chronograph train being at the same time braked to avoid backlash in the gearing. As shown, a third wheel pinion 20, Fig. 2a, drives a wheel 19 and thus normally also a wheel 5 and a chronograph seconds hand shaft 18 which are frictionally coupled thereto by a spring 23, as in Specification 1403127. Operation of start-stop control member 29 to the "stop" position frees the wheel 5 and the shaft 18 from the wheel 19, and brakes the wheel 5 by pressing it against frame plate portion 2a. The member 29 carries conical pins 27 which produce axial displacement of a disc 26 for the declutching and braking action, and the member is displaced in alternate directions by successive operations of a pusher 48, Fig. 1. These displacements are produced by a swivelling finger 49 which acts on a reversing lever 55 as shown, or directly on the member 29. A locking lever 58 ensures that a zeroing member 35 cannot be actuated when the member 29 is in the "start" position shown, and in this position a brake lever 66 is held away from the shaft 18. Operation of the zeroing member 35 in the direction of arrow 59 uncouples chronograph minute and hour shafts 31 and 39 from wheels 11 and 17 respectively and actuates hammers 63-65 to return all three hand shafts to zero by acting on heart pieces 30, 37, 44, at the same time lifting the brake 66 off the shaft 18. The wheel 17 at the other end of the chronograph train is then braked by a four-armed resilient washer 45.