GB663880A - Improvements in or relating to intermittent movements - Google Patents

Abstract

663,880. Intermittent toothed gearing. GENERAL PRECISION LABORATORY, Inc. Jan. 18, 1949 [Jan. 28, 1948], No. 1424/49. Class 80 (i) [Also in Group XX] In mechanism of the kind in which a gear wheel, driving a sprocket, is rotated intermittently by a continuously rotating cam disc having a main portion perpendicular to its axis of rotation and an offset peripheral portion which advances the gear wheel by one tooth at each revolution of the cam, resilient or frictional means is provided to maintain only one face of a tooth of the gear wheel in contact with the cam. The Figures show two perpendicular elevations each partly in section of one embodiment applied to kinematograph apparatus. The sprocket 31 is carried on a shaft 28 secured to or integral with a wheel 27 with teeth 29. One of the teeth normally rests on the face of a disc 23 at the end of a continuously driven shaft 12. A portion 26, struck out of the plane of the disc, however, feeds one tooth for each revolution of the shaft 12. A spring 36 is secured at one end to a pin 38 on the shaft 28 and at the other to a pin 39 carried on a gear wheel 41 rotatable round the shaft 28. This gear wheel meshes with a gearwheel 47 on a shaft 48 driven by worm and worm wheel 22, 49 from the shaft 12. The ratio of this train is chosen to secure a constant average tension in the spring 36 and maintain the operative tooth 29 secure in engagement with the disc 23. The shaft 12 rotates in a bush '16, axial movement being prevented by the hub 19 of the worm 22 and a collar 51. The bush is screw threaded at 14 into a fixed member 13 and by rotating the bush, through a flexible shaft 58 and gearing 55, 56, an axial movement is produced which rotates the gear 27 to provide an additional movement to the sprocket to frame the film in the projection aperture. In another embodiment the spring 36 and associated gearing are dispensed with and the engagement of the operative tooth 29 with the disc 23 is secured by a frictional device which retards the shaft 28.