| 摘要 |
607,600. Toothed gearing. THORENS SOC. ANON., H. April 25, 1945, No. 10426. Convention date, July 11, 1944. [Class 80 (i)] [Also in Group XXXVIII] In a toothed gear with cyclically variable ratio, used in a magazine gramophone to extend the time period between successive records, two identically cut gear-wheels 7, 8 are mounted closely together on a shaft 4 carrying a cycling cam 5, Fig. 2, which performs one complete revolution at each record-changing cycle. The lower gear-wheel 8 is mounted freely on the shaft 4, while the upper gear-wheel 7 is fixed and provided with a raised sector 71 which is sufficiently displaced to avoid engagement with a pinion 12 driven by a motor via a pinion 6, Fig. 1. The sector 7<1> is disposed at a part of the gear-wheel 7 such that it reaches the pinion 12 soon after the commencement of rotation of the cycling cam, i.e., during the period that the pick-up arm is lifted and moved outwardly across the record. A shaft 18, having a pinion 17 fixed to it, is arranged to be axially displaceable by a manually operated lever 20, so that in the upper position the pinion 17 will only engage the gearwheel 7, including the raised sector 7<1>, but in the lower position it will also engage the gearwheel 8. During a cycle of operation when no pause is required, the pinion 17 is set to engage both gear-wheels 7, 8, when the shaft 4 will revolve at a uniform speed without interruption, even when the raised sector 7<1> is passing the pinion 12. If, however, the pinion 17 is set to the upper position, the drive to the shaft 4 is interrupted when the raised sector 7<1> reaches the pinion 12, but a resilient arm 25 fixed to the underside of the gear-wheel 8, which continues to revolve, engages at each revolution one tooth of a star wheel 24 mounted on and fixed to the shaft 18, thereby causing the shaft 4 to be rotated through a small angle. The movement of the pinion 12 is therefore transmitted at reduced speed to the shaft 4 until the sector 71 has passed the pinion 12, or until the shaft 18 is set back to the lower position.
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