GB878075A - Improvements relating to belt and pulley transmissions - Google Patents

Abstract

878,075. Belt and expanding-pulley gear. SAMPIETRO, A. C. June 17, 1959 [June 24, 1958], No. 20255/58. Classes 80 (1) and 80 (2). [Also in Group XXXI] The adhesion of a driving belt 10, Fig. 1, on a pulley 11 is increased by an auxiliary belt 14 which laps freely rotatable auxiliary pulleys 15, 16 and presses the main belt 10 against its pulley. The pressure can be altered by adjusting the position of one or both auxiliary pulleys relative to the main belt. As shown, the axis of pulley 15 is fixed and that of pulley 16 is adjusted by supplying fluid pressure to a cylinder 22 slidable on a pivoted piston 23. The main pulley may be of the variable diameter expanding type having twin conical discs. In a speed-sensitive pulley, Fig. 2, the pulley discs 41 are slidable on splines on radial discs 34 secured to a shaft 30 and the spacing of the discs 41 is automatically controlled by centrifugal balls 33 radially slidable between the discs 41, 34 formed with radial guide ribs 35, 42, and opposed by the tension of the belt 43, which latter may have a rubber base 43 reinforced by a steel band 44. Fig. 3 shows the discs 55 slidable on splines on a shaft 50 and formed with annular cylinders 56 which cooperate with annular pistons 57 fixed relative to the shaft and to which fluid pressure can be supplied through ducts 58-63 to alter the spacing of the discs. In Fig. 4 (not shown) the pulley discs are slidable on splines on the shaft and are spring loaded towards one another so that the spacing depends on the tension in the driving belt. Fig. 5 shows an arrangement in a motor vehicle wherein front-mounted pulleys 84 each drive pulleys 85 geared to each rear wheel, supported on swinging arms 83, drive being through long belts 86 running along the sides or centrally of the vehicle under jockey-pulleys 92, and eliminating need for the usual differential gear. Auxiliary belts 90 are loaded by hydraulic jacks 91, as in Fig. 1, all supported by the wheel-carrying structure. Either the input or output pulleys 84, 89 may be of variable diameter, in which case the input pulley diameter may be controlled by centrifugal, hydraulic, or belt-tension responsive means. As applied to a front-wheel drive motor vehicle, Figs. 6, 7, a wheel-mounting arm 95 in which the driving pulleys are mounted in rotatable about an extension 98 of the engine gear casing and is sprung by a rubber ring 101 mounted in torsion between the arm 95 and the casing 98. A drive shaft 109 from the engine is connected to a speed-responsive pulley 112 (see Fig. 2 above) lapped by a belt 116 driving a spring-loaded pulley 113 connected through a reduction gear 120 and a universal coupling 105 to the road wheel 104. Owing to the comparatively large diameter of the pulley 113 the adhesion-promoting device is applied only to pulley 112 where the auxiliary belt 125 laps pulleys 124 mounted on a frame having a rod 122 slidable in a tube 123 mounted on a cylindrical member 126 connected to the arm 95 and the lower end of the casing is closed by a flexible sleeve 131. The frame for the adhesion-promoting belt is biased by a spring 127 towards the driving belt as it laps pulley 112, but the spring effect is modified by connecting the cylinder 126 to the engine manifold which controls the effective diameter of the driving pulley 112.