A speed change device includes a sun gear. A plurality of intermediate gears surround the sun gear. Each of the plurality of intermediate gears includes a forward set of teeth and an aft set of teeth. A ring gear surrounds the plurality of intermediate gears. The ring gear includes a forward portion with a forward set of teeth in meshing engagement with the forward set of teeth on each of the plurality of intermediate gears and an aft portion with an aft set of teeth in meshing engagement with the aft set of teeth on each of the plurality of intermediate gears. A carrier includes a carrier forward portion and a carrier aft portion. Each of the plurality of intermediate gears are located axially between the carrier forward portion and the carrier aft portion.

A housing includes an accommodation space for a prime mover and a speed reducer. A rotational translation unit includes a rotation portion that rotates relative to the housing upon receiving torque outputted from the speed reducer, and a translation portion that moves relative to the housing in an axial direction according to rotation of the rotation portion. The accommodation space is between the rotation portion and the housing. A clutch in a clutch space allows or interrupts transmission of torque between a first transmission portion and a second transmission portion. The rotation portion is between the clutch space and the accommodation space. A sealing member has an annular shape in contact with the rotation portion, and maintains an air-tight or liquid-tight state between the accommodation space and the clutch space.

An actuator is provided which includes a stationary frame; an output plate disposed within said stationary frame; a top plate; a stator disposed between said stationary frame and said top plate, said stator describing an annulus; a rotor disposed within the annulus of said stator; a principal bearing disposed between said stationary frame and said output plate; a pinion gear; and a star gear which meshes with said pinion gear.

Pericyclic transmission having at least one input shaft (58) rotatable about an axis of rotation and at least one inclined bearing seat (55, 56) secured to the input shaft with the inclined bearing seat being oriented at an inclination angle with respect to the axis of rotation of the input shaft. An input gear (52, 54) is attached to each inclined bearing seat with the input gear being oriented at the inclination angle and having an axis of rotation inclined to the axis of rotation of the input shaft by the inclination angle whereby upon rotation of the input shaft, the input gear performs at least a nutating motion. The transmission also includes an intermediate gear (51, 53) in mesh with the input gear with the intermediate gear having an axis of rotation coincident with the axis of rotation of the input shaft. The intermediate gear communicates with a transmission output.

A power transmission device includes a pinion gear having a large pinion gear and a small pinion gear, a carrier that supports the pinion gear, a ring gear that engages with the small pinion gear, an oil supply unit positioned above a horizontal line that passes through a revolution center of the pinion gear, and a downstream side wall part facing a gear surface of the large pinion gear. The downstream side wall part is arranged to be adjacent to the oil supply unit further downstream in a revolution direction of the pinion gear than the oil supply unit when viewed from an axial direction.

A power transmission device includes a box, a case disposed in the box, a differential mechanism housed in the case, and a planetary gear mechanism disposed in the box and supported by the case. The planetary gear mechanism includes a sun gear and a pinion gear that engages with the sun gear. The box has a shelf part above a horizontal line that passes through a revolution center of the pinion gear. The shelf part is arranged at a position that does not overlap the sun gear when viewed from radially above.

A gearbox is disclosed. The gearbox can have planetary gears. Each planetary gear can revolve around a rotational center of itself while concurrently revolving around a rotational center of the gear system as a whole. The gearbox can be used to deliver rotational output energy at a right (or other angle) from the direction of a received input energy.

A prime mover includes a stator fixed to a housing, and a rotor rotatable relative to the stator. The prime mover outputs torque from the rotor by being supplied with electric power. A speed reducer reduces the torque of the prime mover and outputs the reduced torque. The speed reducer includes a sun gear to which the torque from the rotor is input, and a planetary gear that revolves in a circumferential direction of the sun gear while rotating in a state of meshing with the sun gear. The rotor and the sun gear are formed separately, and are disposed coaxially so as to be integrally rotatable.

Torque of a prime mover is input into a sun gear. A planetary gear revolves in a circumferential direction of the sun gear while rotating and meshing with the sun gear. A carrier has an annular shape, rotatably supports the planetary gear, and is rotatable relative to the sun gear. A first ring gear is fixed to a housing, and meshes with the planetary gear. A second ring gear meshes with the planetary gear, is different from the first ring gear in number of teeth of a tooth portion, and outputs torque to a rotation portion. At least a part of the sun gear in an axial direction is located radially inward of the carrier. At least a part of the first ring gear and at least a part of the second ring gear in the axial direction are located radially outward of the carrier.

A reduction gearbox is provided that includes a planetary gear arrangement disposed in a casing. The planetary gear arrangement includes a sun gear, planet gear assemblies, and a fore and aft ring gears. The sun gear is configured in communication with a cantilevered end of an input. Each planet gear assembly has a main gear meshed with the sun gear, a fore lateral gear and an aft lateral gear disposed on opposite sides of the main gear and rotating therewith. The main gear has a main gear pitch diameter and the fore and aft lateral gears having a lateral gear pitch diameter. The fore ring gear is meshed with the fore lateral gears. The aft ring gear is meshed with the aft lateral gears. The aft ring gear is independent of the fore ring gear. The planet gear assemblies are in communication with an output.