GB511327A - An improved time measuring apparatus comprising a synchronous motor and an auxiliary movement - Google Patents

Abstract

511,327. Electric clocks. LANDIS & GYR AKT.-GES. Aug. 2, 1938, No. 22857. Convention date, Sept. 2, 1937. [Class 139]. In a time-measuring apparatus (e.g. for driving a switch disc) having a synchronous driving motor and a spring-driven reserve movement, a separate detent relay 2 for holding and releasing the escapement 21 is of low voltage relatively to the voltage of the motor. The winding of this detent relay is in series with the exciting coil of the motor or is in parallel with a portion of said coil. The relay armature 6, 3 is attached to the end 10 of a lever 11 which is pivoted at 12 weighted at 13 and counter weighted at 14. Attached also to shaft 12 is an arm 18 moving between stops 15, 16 and a leaf spring 17 coacting with stop 19 and with a pin 20 on the balance 21 of the reserve movement. The relay bobbin is wound directly on to core 1, the latter being carried by insulation. Under normal conditions, with current flowing and the synchronous motor 25, Fig. 1 (not shown) driving the switch disc, the lever 11 is attracted counterclockwise to the position shown, the blade 17 being stressed against the stop 19 and its end arresting the stop 20 in a position in which the hairspring is still partially stressed. At current failure, or fall, armature 3 is released, arm 18 moves till it meets the still stressed blade 17 and the latter is next removed suddenly from pin 20 on to pin 16 so that the balance starts automatically owing to the stored energy in the hairspring. To avoid sticking of the balance, the lever 11 is rocked periodically to free the wheel 21 by a pin 40, Fig. 1 (not shown) on a gear wheel rotated by the synchronous motor. The reserve movement may be a pendulum movement, and a spring may replace the weight 13. The exciting coil of the motor may have tappings so that the apparatus may be used with different voltages.