GB666772A - Improvements in or relating to timepieces - Google Patents

Abstract

666,772. Clocks and watches. ANDREWS, G. S. Aug. 16, 1948 [Aug. 28, 1947], No. 21573/48. Class 139. In a timepiece the curb pins are moved along an arc of the hairspring as the mainspring unwinds, which arc is adjustable in length. In one embodiment (Fig. 1) the curb pins 26 are carried by an arm 27 pivoted on the balance staff 22 and frictionally connected to one end of a lever 28, the other end of which is urged against a helical spring 34 rotated through gearing by the mainspring. The top end of the spring 34 is adjustable and as the arm 27 may be moved relatively to the lever 28 the length of the are of movement of the curb pins may be initially set. In another embodiment, not shown, a spiral spring is used in place of the helical spring. In another example (Fig. 7) the arm 78 carrying the curb pins 77, frictionally engages a lever 79 connected by a pin and slot connection to a lever 83 having a pin 82 constantly urged against a cam 81 driven from the mainspring. The pin 88 is adjustable along the slot 87 of the lever 83 for setting of the arc of movement of the curb pins. In another example (Fig. 9), the arm 104 carrying the curb pins 103 is frictionally connected to a lever 106 having an adjustable tip 107 urged against a gear wheel 110, which is moved vertically along a screwed shaft 109 as the mainspring unwinds. In another example (Fig. 10), not shown, a gear wheel movable along a screwed shaft as the mainspring unwinds carries a conical cam 129 which co-operates with a pivoted lever of adjustable length which lever moves the lever which is frictionally connected to the arm carrying the curb pins. In another example (Figs. 11 and 12), a spiral cam 146 rotated by the mainspring is vertically adjustable along a shaft 145 and moves a lever 150 frictionally connected to the arm 149 carrying the curb pins 148.