Patent GB-995258-A (GB)
Title: Variable speed-ratio toroidal transmission
IPC: F16H15/38
Filed: 1962-03-07
Abstract: 995,258. Variable speed friction gear. EXCELERMATIC Inc. March 7, 1962 [March 8, 1961], No. 8840/62. Heading F2D. In a variable-speed friction gear in which a plurality of circumferentially spaced rollers are in driving contact between a pair of inwardly facing toric discs, the roller supporting means pivot for ratio changing and also move in a second mode in response to changes in the traction forces on the roller, such movement being balanced against a controllable fluid pressure force, and torque responsive cam means urge the discs in contact with the rollers in addition to a force determined from the controllable fluid pressure. An input shaft 12 carries a toric disc 16 on rubber rings 152, for slight angular self-alignment, and drives the disc through a camming ball torque responsive loading device 130 in which the V-grooves for the balls have a bare radius substantially greater than the balls, the line of action of the device 130 passing through one ring 152 to meet the gear axis between the discs at 154 to facilitate alignment under slight unequal loading of the rollers 20. The shaft 12 is mounted in a bearing 30 carried by an axially movable piston 100. The second disc 18 is rigidly mounted on the output shaft 14. Three idle rollers 20 are mounted on thrust bearings 44, 46, the bearing 46 being mounted on a Belleville washer 49 to limit its thrust loading. The roller spindles 48 are formed with a slot 56 engaged by a pin 60 carried in a slot 58 in roller pivot shafts 50, this connection, together with a tongue and slot 62, 64, allowing contact equalizing movement of the rollers 20. The pivot shafts 50 are carried in ball bearings 52 to allow pivoting for speed changing and also some longitudinal movement against a spring 66 and dash-pot 95 under traction forces developed on the roller. These traction forces are balanced by fluid pressure acting on a piston 72 (Fig. 3), the pressure being generated by a pump 80 and controlled by a relief valve 84 and manual valve 86. Fluid pressure from the line 82 passes through a pressure augmenter 108 through a restriction 114 and one-way valve 112, having a return bleed 113, to the rear of the piston 100 to urge the toric discs into contact with the rollers. The pressure in the line 110 is controlled by a needle valve 116 positioned by gearing 118, 120 according to the speed ratio of the toric gear as determined by the angular position of one roller pivot shaft. The pressure balancing of the rollers and pressure loading of the toric discs allows a residual loading to be maintained for a short while on sudden torque fall-off to allow for inertia effects on the rollers. In modifications, the balls of the torqueresponsive device 130 are replaced by conical or barrel-shaped rollers, and the devices may be fitted to both input and output shafts. In a second embodiment, the fluid pressure loading of the rollers is provided from the piston 72 which acts through a lever 68c on the end of a pin 180 spring-loaded within the roller pivot shaft 50c and carrying a roller 190 engaging a sloping surface 188 on the back of the roller spindle 48c which is pivoted at 186 on the shaft 50c. Thus the controllable pressure produces axial engaging thrust on the rollers 20c and balances the traction loading. In a third embodiment the roller spindle is acted on by an axially moving piston mounted in the pivot shaft and having an entry passage coaxial with the shaft.