GB639992A - Improvements in gravity escapements and clocks embodying the same - Google Patents

Abstract

639,992. Clocks. MAINS TIME CO., Ltd. Jan. 3, 1947, No. 314. [Class 139] A gravity escapement comprises a pendulum 16, Fig. 1, a pallet 17 mounted on the pendulum, a movable mass which when allowed to fall impulses the pendulum and means independent of the pendulum to raise the mass back to its starting point said means operating only after the movable mass has imparted its impulse. A gear .wheel 7 mounted on a spindle 8 is driven through a friction clutch by a synchronous motor 1. The spindle 8 carries a snail cam 9 which cooperates with a vertical detent 10 as described later. A bell-crank lever 13 is pivoted at 12 on the cam 9 and one of its arms is bent over at 13a to form a trip member while the other arm 14 carries a pin 15, 15a the end 15 of which cooperates with the pallet 17 and the other end 15a of which co-operates with a pair of ramps 18 and 19. The arrangement is such that when the snail cam 9 is arrested by the detent 10, Fig. 3, the end 15a of the pin 15 leaves a gate 21 in the ramp 19 and the bell-crank lever 13 rocks clockwise due to gravity. The end 15 of the pin 15, 15a strikes the pallet 17 thus impulsing the pendulum as it moves to the right. The pin 15, 15a then slips from the pallet and the end 13a of the bell-crank trips the detent 10 so that the snail cam 9 is again driven anti-clockwise. The end 15a of the pin 15, 15a meets the surface 18a, Fig. 1, of the ramp 18 and is moved therealong, Fig. 8, by the continued rotation of the cam 9. The pin 15, 15a slips under the foot of the ramp 19 and is then moved up the side 19a back into the gate 21, Fig. 10. The rotation of the gear train 23 for the hands 24, Fig. 1, is thus controlled by the pendulum 16. A wheel 26 driven from the gear train 23 carries a disc 27 on which are mounted two diametrically opposite pins 28, 29 which co-operate with an arm 30 for effecting periodic closure of a mercury switch 31 to send impulses to slave clocks.