GB659729A - Improvements in mechanical drives - Google Patents

Abstract

659,729. Driving sound reproducing machines. PHILIPS ELECTRICAL, Ltd. Nov. 21, 1949, No. 29714. Convention date, Nov. 24, 1948. [Class 40 (ii)] [Also in Group XXIV] Arrangements of belt reduction gearing are described which reduce the radial bearing pressure on the driving shaft. A member to be driven, e.g. the turntable 4 of a gramophone, is engaged by two belts 6, 7, each driven by a driving pulley 1 and passing over guide pulleys 8, 9. As shown, the planes containing the axis of the driving pulley and the axes of the pulleys 8, 9 are inclined at an angle of 150 degrees but the angle may be increased up to 180 degrees if larger pulleys are used. A two-speed belt reduction gear (e.g. for longplaying records) is also described, Fig. 3 (not shown), in which the two guide pulleys are mounted on a plate pivoted so that either belt may be brought into contact with the turntable 4. The belts are driven at different speeds by two pulleys on the driving shaft, and the plate may be resiliently mounted to provide belt driving pressure. Alternatively, the turntable and tone arm may move to engage either belt. In a modification, Fig. 2 (not shown), one belt is used for a single-speed drive, the driving pulley being situated between two quick pulleys, one larger than the other. The guide pulleys may be resiliently mounted to maintain belt tension, or jockey pulleys may be provided.