GB986288A - Improvements in or relating to timing devices - Google Patents

Abstract

986,288. Toothed gearing. S. SMITH & SONS (ENGLAND) Ltd. Dec. 18, 1963 [Oct. 22, 1962], No. 39976/62. Heading F2Q. [Also in Divisions G3 and H2] A time alarm or electric time switch actuator of the kind in which an actuating spindle 1 is manually rotated to tension a driving spring fixed to the spindle and on release is returned by the spring under the control of a timekeeping escapement in train with a pinion (not shown) which engages a gear-wheel 24 fast with the spindle, is arranged so that the wheel 24 disengages from this pinion during one part at least of the return movement, whereby a rapid actuating movement of the spindle to actuate the alarm or switch, is permitted, followed by further movement under control of the escapement. The teeth of gear-wheel 24 are cut away over a sector as indicated by full and dotted line. A superimposed gear sector 25 free on the spindle is movable relative to gear 24 between extreme positions determined by stop faces 38, 39 co-operating with a lug 37 on gear 24. A light spring (not shown) normally biases gear sector 25 to the extreme position shown in Fig. 3. The teeth of sector 25 partly overlap and coincide with the teeth of gear 24 in both extreme positions and the pinion can engage both gears simultaneously. Assuming that the spindle is wound clockwise to a position in Fig. 3 where the pinion engages only the gear 24, then on running down anticlockwise to a position where the pinion engages only the sector 25, gear 24 is freed from the escapement and can rotate rapidly to the position of Fig. 2 taking up the lost motion. Further rotation of the spindle under control of the escapement is then continued until sector 25 also disengages from the pinion, whereupon the spindle 1 is again permitted free rotation back to an initial position. In a modification, two spaced tooth portions of the superimposed sector overlap two cut-away portions of the gear 24, whereby two periods of rotation free of the escapement are permitted in addition to a third such period which takes the spindle back finally to its initial position. The pinion may be of the " kick-out " type to allow of winding the device. Specification 968,587 is referred to.