GB980563A - Improvements in or relating to timing devices - Google Patents

Abstract

980,563. Timing devices. S. SMITH & SONS (ENGLAND) Ltd. Oct. 25,1963 [Nov. 16, 1962], No. 43348/62. Heading G3T. A timing device of the kind in which a spindle 4 is rotated by hand from an initial position to wind up a driving spring 25 and on release is rotated back to its initial position by the spring under the control of a constant speed device or balance escapement 31, 32, is characterized by a spiral cam driven by the spindle and a co-operating cam follower arranged to disconnect the constant speed device over a predetermined range of movement adjacent to the initial position, whereby a period of timing rotation is followed by a period of rapid rotation which is terminated when the spindle reaches its initial position. The spiral cam track 6, on a disc 5 fast with the spindle, engages a follower 33 carried by a lever 8 which has an index 34 co-operating with a fixed scale. A second cam 7 on the spindle moves a lever 15 to establish a driving connection between the spindle 4 and the escapement 31, 32 on winding up the device, this connection being broken before the spindle returns to its initial position, the period of rapid rotation serving to actuate an alarm hammer 29 through another escapement lever 28 and escape wheel (not shown). Spindle 4 has rotatably mounted on it a gear wheel 26 connected to the spindle through a friction clutch 44. A common gear 43 meshing with wheel 26 drives the alarm train 27 and also a timing train 30. This timing train includes a pinion 41 carried on a tilted arbor 20 of which one end is journalled in a spring bearing 35 in one arm of the lever 15. A second arm 16 of this lever is engaged by the cam 7 to move the pinion 41 into mesh with the common wheel 43 as the device is wound up. Lever 15 has a third or detent arm 17 biased by one prong of a two-pronged spring 21, of which the other prong biases a pivoted latch 13. On winding up, the detent arm 17 is engaged by the latch 13. The time indicating lever 8 has an extension 10 which on running back of the device releases the latch 13 so that the lever 15 is moved to disengage the drive to the time measuring excapement 31, 32 at a predetermined position.