GB821860A - Variable speed drive transmission - Google Patents

Abstract

821,860. Variable-speed gearing. ROLLER GEAR CO. Inc. Sept. 24, 1956 [Sept. 23, 1955], No. 29113/56. Class 80 (2). Variable-speed friction gearing comprises balls 23 capable of free rolling movement in all directions and spaced by rollers 24 in a spider 25 and arranged between coaxial pairs of inner and outer races, of which the outer races 11, 13 are carried by a driving- shaft 5 and are movable apart or together to vary the gear ratio while one inner race 14 is fixed to a driven shaft 7 and the other inner race 15 is slidably keyed on shaft 7. The difference between the radius of curvature of the outer races 11, 13 and the radius of the balls 23 is at least twice the difference between the radius of curvature of the inner races 14, 15 and the balls 23. The outer races may, therefore, be conical. The race 11 is secured to a piston 10 slidably keyed on shaft 5 and is slidably keyed to a cylinder 12, to which latter the race 13 is fixed. Contact pressure between the balls and races is provided by a spring 50 and by loadresponsive means comprising balls 18 in helical grooves on members 16, 17 mounted on shaft 7 and on an output shaft 6. Hydraulic ratioadjusting means comprises a manually or automatically (by engine speed, torque or fuel supply) operated sleeve valve 38 controlling supply of oil from a gear pump 40, 41 driven by shaft 5 to a space 46 in the cylinder 12, so as to move the outer races apart or together. In the planetary form shown in Fig. 1, affording both forward and reverse drives, the spider 25 is driven in the same direction as shaft 5, but slower from cylinder 12 through a spring-loaded friction coupling 30 and planet gearing 32, 34, 35, 36. In the event of overloading, the friction coupling 30 slips. In the non-planetary form shown in Fig. 5, the spider 25 is stationary or is frictionally secured to the casing so as to be capable of slipping at overload, and the hydraulic pressure acts positively both in forcing the races 11, 13 together and in forcing them apart. In this case, the cylinder 12 has two pressure spaces 46, 72, space 46 being bounded by piston 10 and space 72 by a piston 63 rigidly connected to piston 10, the control sleeve valve 38 controlling the supply of oil to the two spaces. By connecting the hollow shaft 6 of the gear to a gear annulus 83, shaft 5 to a sun-gear 85, and a planet carrier 86 to a final output shaft 88, both forward and reverse drives of the latter can be obtained.