Patent GB-1469181-A (GB)
Title: Friction gear with infinitely variable transmission ratio
IPC: F16H15/50
Filed: 1974-03-20
Abstract: 1469181 Variable-ratio gear G JESSE 20 March 1974 12442/74 Heading F2D A steplessly variable-ratio friction gear comprises a radially faced friction disc 5, Fig. 13, on one shaft 1, tracked by rollers 7 carried on a member 17 on a shaft 30 rotatable about a fixed axis parallel to that of the shaft 1, the rollers 7 being rotatable on pins 10 which are bodily turnable about axes parallel to the shafts 1, 30, so that the axes of the roller pins 10 always intersect a straight line parallel to the shaft axes and shiftable with respect thereto to vary the speed ratio. In the explanatory Fig. 5, 56<SP>1</SP> is the axis of the friction disc 59, 57<SP>1</SP> the parallel axis of the member 67 carrying the rollers 73, 73a, the axes of which have been turned to intersect continuously an axis 78<SP>1</SP> parallel to 56<SP>1</SP>, 571. During relative rotation between the disc 59 and roller carrier 67, the rollers 73, 73a are cyclically constrained to roll and slide on the disc in a trochoidal path about a centre spaced from their natural rolling centre, producing a force component radial to the axis 57<SP>1</SP> which applies a drive torque to the disc, reverse for the position shown, forward if the intersection point 78<SP>1</SP> lies on the opposite radial side of the axis 57<SP>1</SP>, and zero if 781 coincides with 57<SP>1</SP>. In Fig. 13, the roller-carrying pins 10 are mounted in forked trunnions 19, turnable in the member 17 about axes parallel to the shaft axes, and haying secured to them arms 21 slidable in grooves 23 in arcuate segments 25 engaging a facial groove 26 in a ring 27 prevented from rotation by a radial bar 28 and adjustable radially to produce cyclic turning movement of the trunnions 19 so that the axes of the roller-carrying pins 10 intersect the radially adjustable point (78<SP>1</SP>, Fig. 5). In Fig. 14, not shown, the ring 27 shifts the trunnion arms outwardly only, in opposition to return springs (50), whilst in Fig. 3a (not shown) the trunnion arms are again shifted positively in both directions through forks (49a) on the arms embracing the ring 27. The trunnion pins 19 are supported axially in the carrier 17 by thrust bearings 18, and the friction disc 5 is connected to its shaft 1 through a cam and pin coupling 40, which applies a torque-responsive axial thrust to the disc 5 through a spring 41. In Fig. 16, not shown, a friction disc provides a degree of positive drive by being faced with a surface of axial pins supported by a rubber backing plate which yields to permit the rollers 7 to penetrate the pin surface. In Figs. 17 to 21, not shown, two gears such as that in Fig. 13 are placed in parallel back to back, one shaft (56) carrying two spaced friction discs (58, 66) between which is interposed a roller carrier (69) on the parallel other shaft (57) which carries, on adjustably inclined trunnions (71) pairs of rollers (73, 74) in axial alignment contacting the respective discs (58, 66) outwardly and each other inwardly. In Fig. 20, not shown, the rollers are oppositely inclined in the radial plane and have unequal doubleconed peripheries contacting each other on one coned part and the discs on the other. Roller inclination is adjusted by a screw (86), shifting a ring (78) embraced by forks (76, 76<SP>1</SP> &c.) on the trunnion arms.