Patent GB-1465838-A (GB)
Title: Variable speed friction drives
IPC: F16H15/50
Filed: 1974-02-11
Abstract: 1465838 Variable-speed gear A L NASVYTIS 11 Feb 1974 6091/74 Heading F2D A steplessly variable ratio friction gear comprises two circumferentially distributed sets of oppositely double coned planetary or non- planetary rollers 130, 140, contacted by a sun and ring which are axially split into halves 112, 113, and 133, 134 respectively, moved simultaneously towards and away from each other to make contact with different axial parts of the rollers, and successive rollers are drivingly connected to each other by contacting cylindrical surfaces 141, 142. In Figs. 1 and 2, the rollers 130, 140 are non-planetary, and reverse is provided by a separate output-driven toothed planet gear 160. The radially outer rollers 130 swing radially on tangential links 130b carried by the fixed casing 138, and contact outer ring halves 133, 134, whilst the inner rollers 140 alternate circumferentially with the outer, and are supported only by the cylindrical surfaces 141, 142 and the halves 112, 113 of the central wheel splined on an input shaft 110. Threaded rods 115, engaging the central wheel halves 112, 113, are turned to adjust their separation, and hence the speed ratio, by turning, through a worm 126, ring gear 125 and triple planet set 123, 127, 129, which maintains the adjusting ring gear 125 stationary when the threaded rods 115 are stationary about their axes. The ring halves 133, 134 are carrried on oppositely threaded rods 136 and drive an intermediate output shaft 155 through shells 151, 152 having internal and external gear teeth 137, 150, meshing a wheel 135 carried by each rod 136, the shells 151, 152 being geared to the output shaft 155 through wheels 153, 154 having a lost-motion connection with the shaft whereby the transmitted torque causes relative circumferential movement between the output shells 151, 152 which turns the threaded rods 136 and adjusts the separation of the ring halves 133, 134 to preserve friction contact as the coned rollers 130, 140 are moved radially by adjustment of the central wheel halves 112, 113. The intermediate shaft 155 drives a final parallel output shaft 170 either forwards through a dog clutch 161 and meshing wheels 163, producing output speeds of 2000 to 5000 r.p.m., or reversely through the dog clutch 161 and a wheel 162 meshing a ring gear 172 of a double planet set, comprising planets 160, 165 independently mounted on a free carrier and meshing respectively the ring 172 and an output sun 171; and a fixed ring 168 and input sun 165, reverse being thus torque split, and producing output speeds of zero to 2000 r.p.m. A second embodiment, Figs. 3 and 4, not shown, has two sets of oppositely tapered double coned planetary rollers (215, 225) alternating circumferentially and supported only by axially adjustable sun and ring halves (211, 212 and 220, 221) by interengaging cylindrical end surfaces (226, 227) thereon, and by V-belts (232) driven by a parallel input shaft and engaging grooved pulleys (231) at each end of the radially inner rollers (215). The stationary ring halves (220, 221) are axially adjusted to ramp the speed-ratio by turning oppositely threaded rods (235) which carry them, and the sun halves (211, 212) follow up the consequent radial movement of the coned rollers by automatically screwing along quick-pitch threads on an output shaft (210) which carries them. The contacting friction surfaces of the sun and ring halves, and the cylindrical contacting surfaces, are rubber covered. Forward, zero and reverse output speeds are within the range of adjustment.