Patent GB-529519-A (GB)
Title: Improvements in or relating to striking and chiming clock mechanisms
IPC: G04B21/02
Filed: 1939-05-20
Abstract: 529,519. Striking and chiming mechanism for clocks. MAW, T. F. May, 20, 1939, No. 15104. Addition to 417,700. [Class 139] The invention relates to striking mechanism of the kind having a rotatable hammer-operating member 14, a hammer-actuating lever or slide 19 co-operating with the member 14 to rock the hammer-shaft 16, release means (cam 33, lever 29, 22) actuated from the time train to render the member 14 and the lever 19 operative at striking times, and resetting means 21, 41, 30, actuated from the hammer-shaft 16 to render the member 14 or lever 19 inoperative after the appropriate number of hammer strokes. According to the invention, in striking mechanism of the above kind there is a strike restraining lever 22 between the release cam 33 and the slide 19, and the resetting means acts on the slide 19 through this strike-restraining lever 22. The striking mechanism is preferably combined with chiming mechanism constructed and acting on similar lines. The striking mechanism is carried on a plate 11 so that it may be attached as a separate unit to an existing clock movement, of which 34 is the minute-hand spindle. The hammer-operating cam 14 is mounted on a suitable continuously-rotating spindle 13 of the clock movement. The slide 19 is pivoted to an arm 18 rigid with the shaft 16 of the hammer 17 and has an offset 24 by which it is normally held up out of the path of cam 14 by a strikerestraining lever 22, 29 pivoted at 23. A pawl lever 21, pivoted at 20 to the arm 18, is normally in the position of Fig. 1, in which a lug 31 on it engages a notch 30 in arm 29 to maintain the arm 22 raised. At the hour, or half hour, the rise 35 or 36 of a cam 33 raises the arm 29 to the left so that notch 30 is released from the lug 31 and pawl lever 21 falls on to a fixed pin 39. As the rise 35 or 36 wipes clear, lever 22, 29 falls counterclockwise and allows the slide 19 to fall on to a fixed pin 32, into the path of cam 14, as shown in Fig. 3. Thereafter cam 14 oscillates the slide 19 to rock the hammer-shaft and a pawl 38 on lever 21 actuates a ratchet count wheel 40 frictionally mounted on the minute-hand spindle 34. After the appropriate number of hour strikes the pawl 38 rides on a tooth 41 of half depth so that the end 31 of lever 21 re-engages the hook 30. As lever 21 returns to the left under the weight of hammer 17, the arms 22 and 19 are raised to terminate the oscillations of the hammer shaft 16. A detent 145 on count wheel 40 co-acts with a detent 42 on a wheel 43 which is loosely mounted on spindle 34 and is driven by train 44, 45 to rotate once in twelve hours. Since the wheel 40 has twelve teeth, the detent 145 during each hour moves away from the detent 42 by an amount equal to the number of the next hour to be struck, tooth 41 coacting with pawl 38 as the detent 145, on the return of wheel 40, meets the detent 42. For the half hour, a second cam 47 on spindle 34 coacts with pawl 38 to reset the parts after one stroke. Chiming mechanism. The chiming mechanism of Figs. 4 and 5 is combined with the abovedescribed striking mechanism, the same reference numerals being used for the striking as in Figs. 1 and 3. The chime-hammer actuating cam 61 is on the same shaft 63 as the strike-hammer actuating cam 14 and is wide enough to actuate five slides 60 pivoted to five hammer levers 51 ... 55 carrying the hammers 50. Four levers co-act with gongs and the fifth lever 51 merely causes a pause between chiming phases as set out below. The chime release cam 86 co-acts with a chime restraining lever 68 which supports a lug 70 on a bail 64 which is pivoted at 65, 66 and holds up the hammer-actuating slides 60. The pawl-lever 83, carrying pawl 85, co-acts with a notch in the restraining-lever 68 and is pivoted to an arm 82 which carries a dummy hammer 117 to operate the lever 68 by its weight and is pivoted on spindle 72 for actuation by a pin 81 on the slide 60 of the non-chiming lever 51. Five cam discs 74 ... 78 have each a notch 80 in various places and constitute a chime drum. Offsets 79 on the five levers 60 co-act with these discs so that after release by cam 86 and bail 64 the slides 60 are only actuated by member 61 as their lugs 79 drop into the notches 80. At chiming, a rise of cam 86 lifts lever 68 to the left to release the pawl lever 83 ; lever 68 and bail 64 drop and lugs 79 fall on to discs 74 ... 78. Chiming occurs and after the chime-phase the slide 60 of the fifth lever 51 advances the chime drum to introduce a pause before the next phase. This fifth slide 60, through its pin 81, also rocks the lever 82 and causes pawl 85 to return a chimes count wheel 84 one tooth. This sixteen-toothed wheel 84 is frictionally mounted and has four detents 93 which co-operate with a detent 92 on a wheel 88 driven by a pinion 89 on a spindle 190. The action is similar to the striking detents 145, 42 above. A detent 93 advances during a quarter hour away from the detent 92 by an amount equal to the number of phases to be chimed at the next quarter and when pawl 85 has returned the acting detent 93 to the detent 92, a half depth tooth on wheel 84 raises lever 83, as it moves to the right, to re-hook and then raise the chime-restraining arm 68, the bail 64 and slides 60 to terminate chiming. A lostmotion differential 112, 111, 113 is provided between the striking and chiming operating members 14, 86 to give a pause between chiming and striking. Striking and chiming sequence and silencing devices. Pins 96, 95 on the strike-restraining lever 22 and chime-restraining lever 68 respectively co-act with detents 97 and 104. Normally the detent 104 does not function. Detent 97 has an arm 198 to which is pivoted at 99 a push bar 100. Towards the end of hour chiming, a pin 101 rotating with cam 86 lifts pushbar 100 so that on its last, elevated stroke to the right the pawl lever 83, meets a lug 103 on bar 100 so that the latter slides over pin 101 and moves bar 100 and pivot 99 bodily to the right. This lifts detent 97 about its pivot 98 so that it releases the pin 96, thereby freeing the strike-restraining lever 22 and striking commences. The detents 104 and 97 on pivot 98 overlie cams 105 and 108 which are mounted on a spindle 106 and are rigid with an indicator 107. By using the indicator to adjust these cams, the striking or chiming or both may be silenced.