Patent GB-533160-A (GB)
Title: Improvements in or relating to speed-multiplying or speed-reducing gear for high-speed machines, more particularly for cycle dynamos
IPC: F16H13/06
Filed: 1939-08-04
Abstract: 533,160. Friction gearing. RABL, A. Aug. 4, 1939, No. 22707. Convention date, Aug. 4, 1938. [Class 80 (i)] In a step-up or reduction friction gear of the epicyclic type, the outer races of a series of friction rollers are driven by a sleeve and the rollers are carried by arms or cages which are secured either to an inner stationary shaft, to the inner race of an adjacent train of the series, or to the outer revolving sleeve. In one form the driving sleeve 1, Fig. 1, has the outer races 2, 5, 8, 11 and 14 secured thereto whilst the inner races 4, 7 and 10 are free to rotate on a central fixed shaft 19, and the last inner race 13 forms the driven member. Each pair of outer and inner races is connected by balls or rollers 3, 6, 9 and 12 respectively, the balls 3 being pivoted to or spaced by a number of arms 21 attached at 20 to the fixed shaft 19. The inner race 4 is thus driven in the opposite direction to the outer race 2 at increased speed and carries the balls 6 with it by means of arms 22. The remaining trains are epicyclic and drive the inner races at successively increased speeds. End pressure to secure the friction drive is provided by a spring 16 abutting on a flange 15 on the sleeve 1 and engaging the outer race 2, each outer race being provided with a ball 17 engaging a cam slot in the sleeve which is so curved that the axial pressure decreases progressively from the balls 3 which rotate at minimum speed to the balls 12 which rotate at maximum speed. More than one ball may be provided on each outer race engaging a similar number of cam grooves, or alternatively the variable axial pressure may be obtained by varying the angles of the conical surfaces engaging the balls. The speed range may be further increased by making the contact points of the outer races nearer to the centres of the balls than the contact points of the inner races. In a three stage gear applied to a cycle dynamo built into the wheel hub, the balls or barrel shaped rollers 3, 6, 9, Fig. 6, are carried by arms 21, 22, the hub 20 of the former being loose on the fixed spindle 19 but capable of being locked thereto by means of a slot 47 and ball 46. The ball 46 is operable, to engage and disengage the drive, by means of an axially movable rod 44 within the spindle actuated by a rotatable nut 43. The inner race 10 of the last stage is attached to the rotor 48 of the dynamo 42. In a further modification the first outer race is secured to the central fixed shaft, alternate balls are carried by arms attached to the outer driving sleeve and the fixed shaft, and each inner race is connected to the outer race of the next stage. In one stage the arms carrying the balls are attached to the preceding outer race. and the final inner race constitutes the driving member In another modification the driving member 38 carries cylindrical rollers 3 by means of arms 37, these rollers engaging a stationary outer ring 40 and a rotating inner cone 36. The next set of rollers 6 is carried by arms 39 on the cone 36 and engages the ring 40 and a further inner cone 36 to drive the latter at the increased speed. The gears may incorporate any number of stages, and may be adapted for high ratio reduction gears also.