Patent GB-417700-A (GB)
Title: Improvements in or relating to striking or chiming clock mechanisms
IPC: G04C21/08
Filed: 1933-10-26
Abstract: 417,700. Clocks. MAW, T. F., 18, Grosvenor Gardens, Golders Green, London. Oct. 26, 1933, No. 29762. [Class 139.] Striking - mechanism comprises a hammer spindle 14, a rotatable operating member 10 therefor, a hammer-actuating lever 11 coacting with the operating member 10 to oscillate the hammer spindle, means controlled from the time train to release the lever 11 into coaction with the member 10 at timed intervals, and means (50, 52, 23) operated from the hammer spindle 14 to render the released parts inoperative after the appropriate number of hammer strikes. Preferably, the clock is driven by a synchronous electric motor. The strike-operating member 10 is rotated continuously with the operation of the normal time train. Member 10 may be driven from the time train or by the electric motor or a separate spring. A two-armed lever 11 is pivoted at 12 to a crank 13 rigid with shaft 14 and hammer arm 15. Spring 16 tends to rock lever 11 counterclockwise and the coaction of stop 17 for lever 11, spring 16 and cam 10 causes the latter to move lever 11 longitudinally. The end 18 of lever 11 is normally arrested by a stop lever 19 pivoted at 20 and rocked up by spring 21 so that its offset 27 bears against a lever 28, which latter is pivoted at 29 and rocked up by a spring 30. Lug 33 on lever 28 coacts with a cam 34 rigid with the minute-hand spindle 35. The two rises on cam 34 are in the position shown in Fig. 1 at the hour and half-hour. The hour wheel 40 carries a resilient catch 47 which coacts with a step 46 on a twelve-toothed ratchet wheel 43 which is mounted frictionally on the minute-hand spindle 35. For the frictional engagement, a collar 44 on wheel 43 carries a spring 45 which, through a slot in the collar, presses frictionally against the shaft 35. One recess between the ratchet teeth, deeper than the rest, is at the position shown at the hour. Coacting with wheel 43 is a pawl 49, 50 pivoted at 12 and resting against a pin 51. Assuming the clock has just struck four, the parts are as shown in Fig. 1, and during the next hour the ratchet wheel 43 is turned through about 120‹. Lug 46 is diametrically opposite the deep notch in wheel 43 and catch 47 has moved one twelfth of a revolution with the hour wheel 40. As soon as lug 46 has met catch 47, slipping occurs between wheel 43 and shaft 35 for the rest of the hour, since lug 46 and wheel 43 are constrained to move at the same rate as the hour wheel 40. During this hour the wheel 43 moves, in all, five-twelfths of a revolution so that the deep notch occupies the same position as the hour hand. Just before the hour, cam 34 depresses lever 28 which in turn depresses lever 19 so that its lug 26 locks under shoulder 54 of lever 23 pivoted at 24. The part 18 is now free from the end of lever 19 but is obstructed by the depressed end of lever 28. Exactly at the hour, cam 34 permits lever 28 to rise, part 18 is now unobstructed and the right hand end of lever 11 moves into the path of cam 10. Each time lever 11 is slid to the left by cam 10, stop 17 and spring 16, the shaft 14 is rocked to effect a strike and pawl 49, 50 restores ratchet wheel 43 one tooth counterclockwise. After five strokes, pawl 49, 50 drops into the deep notch of wheel 43 and a pin 52 on pawl 49, which has been reciprocating in a slot 53 of lever 23, now hits the lower projection of the slot and moves lever 23 to the left. This releases lug 26 and lever 19, and the latter re-locks the part 18 and prevents further actuation of lever 11 by cam 10. For the half-hour strikes there is a disc 57 rigid with cam 34 and having a cutaway part which coacts with a pin 58 on pawl 49. At the hour strikes, this pin is free to move up and down in the cutaway portion, but at the half hours, disc 57 is turned 180‹ from the position of Fig. 1, and the pin 58 can only fall to the periphery of disc 57 when the second rise of cam 34 releases parts 28, 19, 11, 49, and after one stroke of the hammer the pin 52 meets the upper lug of the slot 53 and restores the parts to non-striking position. The frictional mounting of ratchet wheel 43 may be by a helical spring surrounding shaft 35. In a modification, the parts 11, 19, 28, 34, 10 are adapted to a rack-striking mechanism, the latter replacing the parts 43, 49, 46, 47. In another modification of Fig. 1, the usual gear train for operating the striking mechanism is employed and the levers 19 and 28 are arranged vertically.