Patent GB-1341147-A (GB)
Title: Clock mechanism
IPC: G04C21/06
Filed: 1972-02-24
Abstract: 1341147 Striking clocks ERHARD JAUCH 24 Feb 1972 [26 Feb 1971] 8681/72 Heading G3T The mechanism of a chiming clock has a movement, a striking mechanism, a control section for the striking mechanism, a gear motor to drive the striking mechanism, and a battery set which powers the gear motor and the movement, all constructed as separate sub-assemblies and mounted on a support plate 24 or on a housing for the clock mechanism. The battery set and the gear motor are readily replaceable and a manual switch (22, Fig.1 not shown) is provided in the gear motor circuit to switch off the striking mechanism. The control section for the striking mechanism, Fig. 2, comprises a star wheel 48 which is driven indirectly by hour wheel 26 and has three cam teeth 50 and a longer cam tooth 52. The wheel 48, which rotates once per hour, operates a system of levers 58, 62, 66 and 84 so that when, at a quarter-hour, a roller 54 on lever 58 drops from one of the cam teeth 50, 52, a pin 86 on lever 84 closes a switch 88 in the gear motor circuit. The gear motor then rotates striking mechanism shaft 34 upon which is mounted quarter-hour wheel 74. The quarter-hour strike is stopped by one of four pins 76 on wheel 74 engaging a nose 72 on lever 66 which frees a tooth 78 on lever 66 from a pin 80 on lever 84 thus allowing switch 88 to open. After the third quarter a pin 92 on lever 84 drops into a recess 90 on the circumference of the wheel 74 so that only the longer cam tooth 52 can actuate the lever system to close the switch 88. The striking mechanism, Fig.5, comprises an hour cam wheel 110, which actuates hammer 120, and four quarter-hour cam wheels (108, Fig.3  not shown) which actuate further hammers (112), the five wheels being mounted on the striking mechanism shaft 34. The hour cam wheel 110 carries a tooth 118 which engages a tooth 122 on hammer 120 for one hour stroke. A spring- biased member 126 is pivotally mounted on the wheel 110 and has eleven further teeth 124 for the hour strokes two to twelve. Upon rotation of shaft 34 a cam 130 on the member 126 rides over a fixed stop 132, the member being thus pivoted into the position depicted in Fig. 5 where it is held by a spring-loaded pawl 134. In this position of the member 126 teeth 124 can actuate hammer 120. A gear wheel 36, driven indirectly by the hour wheel 26 via intermediate wheels 28, 30 Fig. 2, and 32 (Fig.4 not shown) is loosely mounted on the shaft 34 adjacent to the hour cam wheel 110. The wheel 36 rotates once every 36 hours and has three equi-angularly spaced pins 116, one of which, after the required number of hour strokes, engages the pawl 134 to release the member 126. Member 126 thus moves to the position depicted in Fig. 6 (not shown) in which the teeth 124 can no longer actuate hammer 120. A device for automatically switching off the gear motor during a predetermined period may also be provided. In the embodiment described it comprises a sector 98, Fig.2, and a control cam 96 fitted on the intermediate wheel 30 which rotates once a day. The striking mechanism is stopped by the cam 96 moving lever 66 so that it can no longer engage lever 84; alternatively the cam can be arranged to open a further switch in the gear motor circuit.