Currently, there is no efficient mechanism for speed increasing with very high transmission ratio. Therefore, a planetary mechanism is proposed, with two suns (0b, 3b), having teeth numbers: Z.sub.1,Z.sub.4, one stationary (0b) and one (3b) constituting the input of mechanism, a carrier (1a, 1b, 1c, 1d) constituting the output, and a planetic shaft (2b) with two planets (2a, 2c), cooperating with corresponding suns (0b, 3b) and having teeth numbers: Z.sub.2,Z.sub.3, where the term: Z.sub.1/Z.sub.2.Z.sub.3/Z.sub.4 is closest to 1, so the transmission ratio between moving sun (3b) and carrier (1a, 1b, 1c, 1d) is maximum possible. In a specific case, named “Three Successive Integers Mechanism”, this transmission ratio is equal to k.sup.2, where k is integer, easily taking high value. The applications are unlimited, while some are: —wind turbine, —electric assisted bicycle, —energy storage unit of enormous kinetic energy with k.sup.4 times increased moment of inertia, —mechanically driven supercharger for ICE or fuel cell, —robotic articulated arm (as speed reducer).

A planet carrier (213) for a speed reducer (210) of a turbomachine (1), this planet carrier (213) having a main axis X and comprising: a cage carrier (222) comprising an annular row of axial fingers (282) about the axis X, which comprises first connection elements, and a cage (220) comprising at its periphery housings (280) and second connection elements which are mounted in said housings and which cooperate with the first connection elements to form connections between the cage carrier (222) and the cage (220), which allow at least one degree of freedom,

characterised in that the cage (220) comprises two shells (220a, 220b) which are axially assembled to each other, said first or second connection elements comprising broaches (288) oriented radially with respect to said axis X and passing through radial orifices (220a, 220a2, 220b1, 220b2) of said shells (220a, 220b).

A planet carrier for a speed reduction gear of a turbomachine has a main axis X and includes a cage carrier with an annular row of axial fingers around the axis X, which carry first connecting elements. The carrier further includes a cage having at its periphery housings and second connecting elements that are mounted in the housings and that cooperate with the first connecting elements to form connections between the cage carrier and the cage, which allow at least one degree of freedom. The cage comprises two shells that are axially fastened to each other and separated from each other by a plane. The housings are formed respectively in the shells.

A gear assembly for use with a turbomachine comprises a sun gear, a plurality of planet gear layshafts that each support a first stage planet gear and a second stage planet gear, and a ring gear. The sun gear is configured to rotate about a longitudinal centerline of the gear assembly, and the plurality of planet gear layshafts comprise an interior passage that receives one or more lubrication supply lines.

A mechanical part for an aircraft turbomachine is made of metal and includes at least one profiled surface configured to ensure an oil flow during operation. The surface has a hydrophobic and/or lipophobic coating or a surface texturing rendering the surface hydrophobic and/or lipophobic.

A bearing lubrication structure for a wind power gearbox includes a housing, a bearing, a planet carrier, and an oil scraper assembly. The planet carrier is rotatably disposed on the housing through the bearing. A first end face of the planet carrier and a second end face of the housing form a receiving chamber. The oil scraper assembly is disposed on the second end face and is located in the receiving chamber. The oil scraper assembly includes an oil scraper member. The oil scraper member is configured to, when the planet carrier rotates, collect oil from the first end face and make the oil flow into the bearing.

A power transmission device and a method of manufacturing the same capable of shortening a shaft length and improving mountability are provided. A power transmission device according to the present disclosure includes a planetary carrier configured to support a pinion shaft pivotally supporting a pinion gear, rotatably support the pinion gear, and cause the pinion gear to revolve by rotation of the planetary carrier and a planetary carrier plate fixed fo face the planetary carrier on a side where the pinion gear is positioned, and including dog teeth integrally formed with the planetary carrier plate.

A planet-carrier cage is provided for a turbomachine speed reducer having a planetary gear set. The cage contains a central sun gear and an annular row of planet gears arranged around the sun gear axis and engaging both the sun gear and an internal gear that surrounds the cage. A periphery of the cage has axial receiving elements configured to receive axial fingers secured to a cage carrier of the speed reducer. Each receiving element is penetrated by a radial spindle that guides the rotation of a connection means, such as a swivel joint or a bearing, which is supported by the fingers. The spindles include means for projecting lubricating oil into regions in which the planet gears mesh with the internal gear.

A machining method for forming an opening through a workpiece, serving as a green compact, by moving a milling tool in a radial direction relative to the workpiece is provided. The milling tool includes a first milling tool and a second milling tool. The method includes a pre-machining step of using the first milling tool, and forming the first sidewall surface by rotating the first milling tool so as to cause cutting edges of the first milling tool to cut the workpiece from the acute angle corner to the obtuse angle corner, while leaving a cutting allowance on the second sidewall surface; and a post-machining step of using the second milling tool whose cutting edges are reversed from the cutting edges of the first milling tool, and forming the second sidewall surface by rotating the second milling tool so as to cause the cutting edges of the second milling tool to cut the cutting allowance from the acute angle corner to the obtuse angle corner.

An engine for an aircraft includes an engine core having a turbine, a compressor, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core, the fan having a plurality of fan blades; and a gearbox. The gearbox is an epicyclic gearbox and comprises a sun gear, a plurality of planet gears, a ring gear, and a planet carrier on which the planet gears are mounted. The radial bending stiffness of the planet carrier is equal to or greater than 1.20×10.sup.9 N/m, and/or the tilt stiffness of the planet carrier is greater than or equal to 6.00×10.sup.8 Nm/rad. A method of operation of such an engine is also disclosed.