A planetary gear assembly includes a wheel hub surrounding an axis, and having an end face and a plurality of engaging recesses formed in the end face, and a planetary gear reduce mechanism including a sun gear disposed on and rotatable about the axis, a plurality of planet gears, and first and second ring gears. The planet gears angularly surround the sun gear and mesh with the sun gear and the first and second ring gears. The first ring gear is stationary relative to the planet gears. The second ring gear is arranged between the wheel hub and the first ring gear along the axis. The second ring gear includes a wheel-hub-facing face surrounding the axis and facing the end face, and a plurality of joining protrusions disposed on the wheel-hub-facing face and respectively complementary in shape with and respectively engage the engaging recesses.

A conveyance for surmounting obstacles which includes a first ground engaging arrangement, and a second ground engaging arrangement, and the first and second ground engaging arrangements are operable to move in an alternating sequence of movements to enable the conveyance to surmount obstacles. The conveyance is statically balanced alternately by one then the other of the ground engaging arrangements throughout the sequence of movements. Each ground engaging arrangement includes a forwardly disposed portion and a rearwardly disposed portion which are spaced apart from one another. Each ground engaging arrangement further includes an obstacle accommodating region located between the forwardly disposed portion and the rearwardly disposed portion which can accommodate a portion of an obstacle being surmounted during use.

There is provided a mechanical paradox planetary gear mechanism, including: a sun gear configured to be rotatable together with rotation of an input shaft; a plurality of first planetary gears arranged around the sun gear at equal intervals, and configured to rotate about their own axes while revolving around the sun gear in a state in which the first planetary gears mesh with the sun gear; a first internal gear arranged around the plurality of first planetary gears, and configured to mesh with the plurality of first planetary gears; a second internal gear arranged in the same axis as the first internal gear; and a plurality of second planetary gears respectively arranged on the same axes as the plurality of first planetary gears, and configured to mesh with the second internal gear.

A planetary gear device configured by combining a plurality of planetary gear mechanisms includes first and second planetary gear mechanisms sharing a carrier, wherein each planetary gear mechanism is composed of an internal gear I.sub.k (k is an integer equal to or larger than 2) and a planetary gear P.sub.k which is engaged with the internal gear I.sub.k and revolves in a circumferential direction of the internal gear, the planetary gear P.sub.k of each planetary gear mechanism is composed of a spur gear in the form of an external gear, the planetary gears P.sub.k of the planetary gear mechanisms share a central axis or have central axes integrally connected to integrally rotate on a common rotation central axis line or are integrated with each other to integrally rotate on the common rotation central axis line in order to configure the entire planetary gear device as a two-stage gear mechanism, the planetary gear device is configured such that the number of teeth z.sub.p1 of a first planetary gear constituting the first planetary gear mechanism and the number of teeth z.sub.p2 of a second planetary gear constituting the second planetary gear mechanism are different from each other, the number of teeth on the internal gear I.sub.1 is z.sub.i1, and the number of teeth on the internal gear I.sub.2 is z.sub.i2, an addendum modification coefficient of the first planetary gear is x.sub.p1, an addendum modification coefficient of an internal gear which is engaged with the first planetary gear and constitutes the first planetary gear mechanism is x.sub.i1, an addendum modification coefficient of the second planetary gear is x.sub.p2, an addendum modification coefficient of an internal gear which is engaged with the second planetary gear and constitutes the second planetary gear mechanism is x.sub.i2, a power transmission efficiency of the planetary gear device having the addendum modification coefficients x.sub.p1, x.sub.i1, x.sub.p2, and x.sub.i2 is η, an addendum modification coefficient of the internal gear I.sub.1 is x.sub.i1, and an addendum modification coefficient of the internal gear I.sub.2 is x.sub.i2, and the addendum modification coefficients have relationships in which values selected from combinations of the addendum modification coefficients which maximize or submaximize the power transmission efficiency η within an allowable range of design specifications given in advance are combined.

In one aspect, there is provided a planetary gearbox, comprising a sun gear, a plurality of planet gear assemblies, each planet gear assembly having 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, a diameter of the main gear being different than a diameter of the fore and aft lateral gears, a planet carrier rotatably supporting at least some of the planet gear assemblies, and at least one fore ring gear meshed with the fore lateral gears, at least one aft ring gear meshed with the aft lateral gears, wherein one of the sun gear, the planet carrier, and the ring gears is configured to be operatively connected to an input, one is configured to be operatively connected to an output, and rotation of a remaining one is limited.

An aircraft engine reduction gearbox includes a power input and a power output, and an epicyclic gear train engaged with the power input and the power output. The epicyclic gear train includes a sun gear engaged with the power input and centrally disposed to define a center axis of the epicyclic gear train. Compound planet gears are mounted to a carrier and rotatable about respective planet gear axes. Each compound planet gear has an input gear in meshed engagement with the sun gear, and output gears axially spaced from the input gear. Ring gears are axially spaced apart and rotatable about the center axis. The ring gears are engaged with the power output. Each ring gear is in meshed engagement with one of the output gears.

A drivetrain architecture may include a first shaft for connection to a torque source, a first sun gear attached to the first shaft, a second sun gear attached to a second shaft, a first planet gear attached to a third shaft and in meshing engagement with the first sun gear, a second planet gear attached to the third shaft, a ring gear attached to a fourth shaft and in meshing engagement with the second planet gear, a planet carrier attached to a fifth shaft, the planet carrier supporting the third shaft, a sixth shaft for connection to a first motor generator, a seventh shaft for connection to a second motor generator, a first gear set connecting the second shaft and the sixth shaft, a second gear set connecting the fourth shaft and an eighth shaft and a third gear set connecting the fifth shaft and the seventh shaft.

A planet gear housing assembly in an epicyclical gear assembly comprises an aft planet gear assembly and a forward planet gear assembly. The aft planet carrier assembly comprises an aft flange defining a central aperture and an annular mounting flange positioned forward of and coaxial with said central aperture, said mounting flange forming a forward facing mounting surface comprising a curvic structure. The forward planet carrier assembly comprises a forward flange defining a central aperture and an annular mounting flange positioned aft of and coaxial with said central aperture, said mounting flange forming an aft facing mounting surface comprising a curvic structure. The curvic structures of the mounting surfaces are positioned relative to each other to thereby form a static curvic joint.

A prime mover includes a stator fixed to a housing, and a rotor rotatable relative to the stator. The prime mover is capable of outputting torque from the rotor by being supplied with electric power. A speed reducer is capable of reducing the torque of the prime mover and outputting the reduced torque. The speed reducer includes a sun gear rotatable integrally with the rotor, and planetary gears capable of revolving in a circumferential direction of the sun gear while rotating in a state of meshing with the sun gear. A gear width of the sun gear is set such that a length in the axial direction by which the sun gear and the planetary gear are overlapped is smaller than a gear width of the planetary gear.

A planetary transmission (2) includes a stepped planetary gear (24), or planetary gears, which are connected to each other, that is/are disposed radially between a first shaft (6) and axially-adjacent first and second ring gears (12, 16). The stepped planetary gear, or connected planetary gears, include(s) a first gearing region (26) that meshes with a sun gear (8) on the first shaft (6) and the first ring gear (12), as well as a helically-toothed second gearing region (28) that meshes with the second ring gear (16). A cylindrical support region (32) is coaxially provided on/around the first shaft. The stepped planetary gear or the connected planetary gears is/are supported on the cylindrical support region of the first shaft by the outer circumferential surface of the second gearing region. The second gearing region lies on the addendum circle of the second gearing region.