A mechanical gearbox for aircraft includes a sun gear with an external toothing, a ring gear with an internal toothing, and planet gears which are meshed with the sun gear and the ring gear and which each have a first toothing of average diameter D32 meshed with the toothing of the sun gear, and a second toothing of average diameter D28, different from D32, meshed with the internal toothing of the ring gear. The planet gears are guided by hydrodynamic bearings which each include a first smooth guiding surface extending at least partly under the first toothing, and a second smooth guiding surface extending at least partly under the second toothing.

A mechanical gearbox for aircraft includes a sun gear with an external toothing, a ring gear with an internal toothing, and planet gears which are meshed with the sun gear and the ring gear and which each have a first toothing of average diameter D32 meshed with the toothing of the sun gear, and a second toothing of average diameter D28, different from D32, meshed with the internal toothing of the ring gear. The planet gears are guided by hydrodynamic bearings which each include a first smooth guiding surface extending at least partly under the first toothing, and a second smooth guiding surface extending at least partly under the second toothing.

A carrier assembly has a pair of axially spaced-apart plates defining an axial gap therebetween. The plates have a plurality of planetary bores on a plurality of planetary axes. A plurality of planetary gear mount assemblies are disposed on the planetary axes and mounted within the planetary bores of the gear carrier. Each assembly comprises a journal bearing shaft having a pair of compliance grooves extending axially from opposed axial ends of the shaft. An inner cylindrical surface of each compliance groove defines a shaft mounting surface. A pair of collars is provided to assemble each journal bearing shaft to the carrier. Each collar has a mounting socket mating the shaft mounting surface and an external collar surface matching the planetary bore diameter.

A carrier structure for an epicyclic gear drive is provided. The carrier structure includes carrier elements connected with at least one planet gear and the first carrier element is connected with the second carrier element through at least two struts with the at least two struts having an inclination angle of more than 20° in the direction of a rotation around a rotation axis of the carrier structure.

A gas turbine engine comprises a gearbox comprising a sun gear, an annulus gear, a plurality of planet gears and a planet gear carrier. The sun gear meshes with the planet gears and the planet gears mesh with the annulus gear. Each planet gear is rotatably mounted in the planet gear carrier. The planet gear carrier comprises a plurality of axles arranged parallel to the axis of the gearbox. The axially spaced ends of each axle are secured to the planet gear carrier. Each planet gear is rotatably mounted on a corresponding one of the axles by a bearing arrangement. Each bearing arrangement comprises a journal bearing and a rolling element bearing and each planet gear is rotatably mounted on a journal bearing and each journal bearing is rotatably mounted on an axle by at least one rolling element bearing.

A gear motor for decreasing speed at a mechanical power output is provided with a housing; an electric motor including an outer stator and a rotor surrounded and driven by the outer stator; a planetary gear train including planet gear assemblies, a stationary ring gear at one end of the planet gear assemblies, and a driving ring gear at the other end of the planet gear assemblies. Each planet gear assembly includes a first gear and a second gear coaxial with and co-rotated with the first gear. The first and second gears are disposed in a carrier. The first gear meshes the stationary ring gear. The second gear meshes the driving ring gear. A driving shaft is rotatably disposed through the housing and secured to the driving ring gear as a mechanical power output.

An epicyclic gear train for a turbine engine includes a gutter with an annular channel. A rotating structure includes a ring gear that has an aperture that is axially aligned with the annular channel. Axially spaced apart walls extend radially outward relative to the rotating structure to define a passageway. The passageway is arranged radially between and axially aligned with the aperture and the annular channel. The walls are configured to inhibit an axial flow of an oil passing from the aperture toward the annular channel.

A planetary gear mechanism is desired in which pinion gears can be inserted between support portions on both sides in the axial direction of the pinion gears after the support portions on both sides in the axial direction of the pinion gears are coupled together. In this planetary gear mechanism, a coupling inner portion of a carrier coupling portion is located between a first sun gear and a second sun gear in the axial direction, and a carrier and the carrier coupling portion are formed so that each pinion gears can be inserted between a first shaft support portion and a second shaft support portion in the axial direction from the outside in the radial direction.

A planetary gear mechanism is desired in which pinion gears can be inserted between support portions on both sides in the axial direction of the pinion gears after the support portions on both sides in the axial direction of the pinion gears are coupled together. In this planetary gear mechanism, a coupling inner portion of a carrier coupling portion is located between a first sun gear and a second sun gear in the axial direction, and a carrier and the carrier coupling portion are formed so that each pinion gears can be inserted between a first shaft support portion and a second shaft support portion in the axial direction from the outside in the radial direction.

A turbomachine engine can include a fan assembly, a pitch change mechanism, a vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The fan assembly can include a plurality of fan blades. The pitch change mechanism can be coupled to the fan assembly. The vane assembly can include a plurality of vanes. The core engine can include one or more compressor sections and one or more turbine sections. The gearbox includes an input and an output. The input is coupled to the one or more turbine sections of the core engine and comprises a first rotational speed, the output is coupled to the fan assembly and has a second rotational speed, and a gear ratio of the first rotational speed to the second rotational speed is within a range of 4.1-14.0. The gearbox efficiency rating is 0.10-1.8.