An example traction drive includes a first ring having an inclined surface that is inclined at a first angle; a second ring having a respective inclined surface that is inclined at a second angle different from the first angle, such that the inclined surface of the first ring and the respective inclined surface of the second ring form a groove; a third ring disposed opposite to the first ring and the second ring, and having a respective groove disposed on a surface of the third ring; and a plurality of rollers disposed between, and configured to roll within, (i) the groove formed by the inclined surface of the first ring and the respective inclined surface of the second ring, and (ii) the respective groove of the third ring.

There is provided a drive power transmitting mechanism that can transmit drive power losslessly and can be used in environments where silence is required. The drive power transmitting mechanism includes a rotor having a first outer circumferential surface and rotatable about a first rotational axis, a rotor having a second outer circumferential surface pressed against the first outer circumferential surface and rotatable about a second rotational axis due to a frictional force produced between the second outer circumferential surface and the first outer circumferential surface, a gear rotatable in unison with the rotor about the first rotational axis, and a gear rotatable in unison with the rotor about the second rotational axis, in which the gear and the gear are brought into mesh with each other when the second outer circumferential surface slips against the first outer circumferential surface.

A friction roller-type reduction gear includes a sun roller concentric with an input shaft, a ring roller having a stationary ring roller element and a moveable ring roller element, intermediate rollers in rolling contact with an outer peripheral surface of the sun roller and an inner peripheral surface of the ring roller, a coupling part coupling the ring roller and the output shaft, and a loading cam mechanism having a cam ring for changing contact surface pressure of each rolling contact surface. The outer surface of the sun roller is a concave curved surface of which a shape of an outer edge in an axial cross-section is a single circular arc-shaped concave curve, and an outer surface of the intermediate roller is a convex curved surface of which a shape of an outer edge in an axial cross-section is a single circular arc-shaped convex curve.

A friction roller-type reduction gear includes a sun roller concentric with an input shaft, a ring roller having a stationary ring roller element and a moveable ring roller element, intermediate rollers in rolling contact with an outer peripheral surface of the sun roller and an inner peripheral surface of the ring roller, a coupling part coupling the ring roller and the output shaft, and a loading cam mechanism having a cam ring for changing contact surface pressure of each rolling contact surface. The outer surface of the sun roller is a concave curved surface of which a shape of an outer edge in an axial cross-section is a single circular arc-shaped concave curve, and an outer surface of the intermediate roller is a convex curved surface of which a shape of an outer edge in an axial cross-section is a single circular arc-shaped convex curve.

A sun roller of a friction roller-type transmission includes a movable sun roller element (23) capable of moving in an axial direction. Furthermore, the sun roller is provided with a loading cam mechanism which is formed along the circumferential direction of an input shaft (12), the loading cam mechanism having a first cam surface (75), a second cam surface (77) arranged facing the first cam surface (75) and secured to the input shaft (12), rolling elements (63) held between the first and second cam surfaces (75, 77), and an annular holding device (51), and the loading cam mechanism axially displacing the movable sun roller element (23). The holding device (51) has an inside-diameter-surface guiding part (81) for positioning the holding device relative to the input shaft by being fitted over the input shaft, the guiding part being provided to the inside diameter surface.

A sun roller of a friction roller-type transmission includes a movable sun roller element (23) capable of moving in an axial direction. Furthermore, the sun roller is provided with a loading cam mechanism which is formed along the circumferential direction of an input shaft (12), the loading cam mechanism having a first cam surface (75), a second cam surface (77) arranged facing the first cam surface (75) and secured to the input shaft (12), rolling elements (63) held between the first and second cam surfaces (75, 77), and an annular holding device (51), and the loading cam mechanism axially displacing the movable sun roller element (23). The holding device (51) has an inside-diameter-surface guiding part (81) for positioning the holding device relative to the input shaft by being fitted over the input shaft, the guiding part being provided to the inside diameter surface.

A drive roller (1) comprising a central hub (4), a body (5) extending around the central hub, the body (5) being made of a deformable material, a deformable band (8) extending over a circumference of the drive roller, and first rigid fins (17) and second rigid fins (18) arranged in alternation and extending radially inside the body (5). Each first fin presents a proximal end (17a) fastened to the central hub, and each second fin presents a distal end (18b) that extends in the proximity of the deformable band.

A drive roller (1) comprising a central hub (4), a body (5) extending around the central hub, the body (5) being made of a deformable material, a deformable band (8) extending over a circumference of the drive roller, and first rigid fins (17) and second rigid fins (18) arranged in alternation and extending radially inside the body (5). Each first fin presents a proximal end (17a) fastened to the central hub, and each second fin presents a distal end (18b) that extends in the proximity of the deformable band.

A roller (1) having a rigid reinforcement (4) defining a hub (5) for rotation of the roller about an axis of rotation X and a plurality of bars (6) regularly arranged around the hub (5) and extending parallel to the axis X. The roller further has bushings (10), each engaged on a respective one of the bars (6) and each comprising an outer rigid ring (11) surrounding a bushing body (12) made of deformable material.

A roller (1) having a rigid reinforcement (4) defining a hub (5) for rotation of the roller about an axis of rotation X and a plurality of bars (6) regularly arranged around the hub (5) and extending parallel to the axis X. The roller further has bushings (10), each engaged on a respective one of the bars (6) and each comprising an outer rigid ring (11) surrounding a bushing body (12) made of deformable material.