A reduction gear configured to decelerate and output rotation of a motor includes two-stage planetary gear mechanisms that are provided side by side in an axial direction of the motor and are each configured of helical gears, and a case made of resin and formed into a cylindrical shape, the case incorporating the two-stage planetary gear mechanisms. At least one of an inner engagement ratio of a sun gear and a pinion gear of the planetary gear mechanism in a first stage and an outer engagement ratio of the pinion gear and a ring gear of the planetary gear mechanism in the first stage is 3.0 or more, and both the inner engagement ratio and the outer engagement ratio are larger than an engagement ratio of the planetary gear mechanism in a second stage.

An oil collector for a mechanical reduction gear of a turbomachine, in particular for an aircraft, the reduction gear including a body having two opposite lateral faces configured to extend in part around planet gears of the reduction gear, the collector further including an internal oil circulation cavity connected firstly to oil inlets located on the faces, and on the other hand to at least one oil outlet, characterised in that at least one of the faces comprises includes columns and rows of several inlets each having a recess with a progressively increasing cross-section, each recess being delimited by walls, at least some of the walls having a hydrodynamic profile.

A turbomachine engine can include a fan assembly, a vane assembly, a core engine, a gearbox, and a gearbox efficiency rating. The fan assembly can include a plurality of fan blades. The vane assembly can include a plurality of vanes, and the vanes can, in some instances, be disposed aft of the fan blades. 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.

An apparatus and method for reducing edge contact stress concentrations in a press-fit. The apparatus and method of the present disclosure specifically provide for a press-fit collar having a channel circumscribing a collar axis. The channel having an asymmetrical cross-sectional profile in a radial face. The asymmetrical cross-sectional profile being configured to reduce an edge contact pressure.

A wheel and a vehicle each having a simple structure and capable of moving over a step while maintaining stability at flat ground traveling are provided. A wheel includes an outer ring that rotates about a wheel rotational axis, an arm drive gear that rotates independently from the outer ring about the wheel rotational axis, and an arm capable of rotating about an arm rotational axis fixed to the outer ring, the arm being configured to partially protrude outside from an outer peripheral surface of the outer ring in a radial direction as the arm drive gear rotates relative to the outer ring in one direction (normal rotational direction) and to be housed inside in the radial direction from the outer peripheral surface of the outer ring as the arm drive gear rotates relative to the outer ring in the other direction (reverse rotational direction) opposite to the one direction.

A wheel and a vehicle each having a simple structure and capable of moving over a step while maintaining stability at flat ground traveling are provided. A wheel includes an outer ring that rotates about a wheel rotational axis, an arm drive gear that rotates independently from the outer ring about the wheel rotational axis, and an arm capable of rotating about an arm rotational axis fixed to the outer ring, the arm being configured to partially protrude outside from an outer peripheral surface of the outer ring in a radial direction as the arm drive gear rotates relative to the outer ring in one direction (normal rotational direction) and to be housed inside in the radial direction from the outer peripheral surface of the outer ring as the arm drive gear rotates relative to the outer ring in the other direction (reverse rotational direction) opposite to the one direction.

A journal bearing comprising a first component and a second component, the first and second components being arranged to rotate relative to one another in normal use. The first component comprises a first body, a first layer forming a functional surface facing the second component, and a first subsurface layer between the body and the layer. The first subsurface layer is formed of a material having a first coefficient of thermal expansion in the radial direction, and the first body is formed of a material having a second coefficient of thermal expansion in the radial direction. The first coefficient of thermal expansion is lower than the second coefficient of thermal expansion.

A journal bearing comprising a first component and a second component, the first and second components being arranged to rotate relative to one another in normal use. The first component comprises a first body, a first layer forming a functional surface facing the second component, and a first subsurface layer between the body and the layer. The first subsurface layer is formed of a material having a first coefficient of thermal expansion in the radial direction, and the first body is formed of a material having a second coefficient of thermal expansion in the radial direction. The first coefficient of thermal expansion is lower than the second coefficient of thermal expansion.

A compact geared reduction unit for application with transmission shaft subjected to radial loads, comprising a box-like body inside which a gear system is accommodated for the transmission of rotary motion from a driving shaft to a transmission shaft, which is provided with an output reduction stage of the epicyclic type; the output reduction stage comprises a driving sun gear which rotates about a main axis and a ring gear which is integrally associated with the box-like body, between which multiple planet gears are engaged which are supported in rotation about respective longitudinal axes which are parallel to the main axis by a transmission planet carrier, which in turn rotates about the main axis and is associated so as to be integral in rotation with the transmission shaft at a connection region. The reduction unit furthermore provides for rolling means adapted to support radial loads associated with the transmission shaft.

A compact geared reduction unit for application with transmission shaft subjected to radial loads, comprising a box-like body inside which a gear system is accommodated for the transmission of rotary motion from a driving shaft to a transmission shaft, which is provided with an output reduction stage of the epicyclic type; the output reduction stage comprises a driving sun gear which rotates about a main axis and a ring gear which is integrally associated with the box-like body, between which multiple planet gears are engaged which are supported in rotation about respective longitudinal axes which are parallel to the main axis by a transmission planet carrier, which in turn rotates about the main axis and is associated so as to be integral in rotation with the transmission shaft at a connection region. The reduction unit furthermore provides for rolling means adapted to support radial loads associated with the transmission shaft.