Abstract: A mechanical reduction gear for a turbomachine, in particular for an aircraft, this reduction gear including a sun gear having an axis of rotation, a ring gear which extends around the sun gear and which is configured to be fixed in rotation around the axis, planet gears which are in mesh with the sun gear and the ring gear and which are held by a planet carrier which is configured to be fixed or in rotation around the axis, each planet gear including a first toothing of average diameter D1 for the meshing with the sun gear, and a second toothing of average diameter D2, different from D1, for the meshing with the ring gear, wherein the first and second toothings of each planet gear include herringbone teeth and are symmetrical with respect to a plane perpendicular to the axis and passing substantially in the middle of the planet gear.

Abstract: A ring gear (114) for an epicyclic or planetary reduction gear (110) of a turbomachine, in particular of an aircraft, said ring gear extending about an axis and comprising first and second coaxial annular elements (114a, 114b) and comprising, respectively, two inner annular toothing sets (150) of different orientation, said first and second annular elements further comprising, respectively, first and second radially outer annular flanges (114ab, 114bb) for attaching said first and second elements to each other, characterised in that one of said first and second flanges comprises, at its outer periphery, a cylindrical centring rim (164) configured to cooperate with the outer periphery of the other of said first and second flanges.

Abstract: The invention relates to a pivot (58) for a sliding bearing of an epicyclic train, comprising an annular wall (50) defining an axial passage (51) and comprising a first (52c) and a second (54c) annular groove opening axially in opposite directions (L1, L2) and each defined by two coaxial inner (52a, 54a) and outer (52b, 54b) annular branches formed at the axial ends of the annular wall (50). According to the invention, the recesses (60) are made in at least one bottom wall (52d, 54d) of one of the annular grooves (52c, 54c).

Abstract: The invention relates to the lubrication of a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular walls that are radial with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising orifices for mounting the axes of said planet gears, and the cylindrical wall comprising through-holes for the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage.

Abstract: A mechanical reduction gear of a turbine engine, in particular for an aircraft, includes a sun gear having external toothing, a ring gear which extends around the sun gear and has internal toothing, planet gears which are in mesh with the sun gear and the ring gear and which have toothings of different diameters, a planet carrier which supports bearings for guiding the planet gears in rotation, and a lubrication circuit of the reduction gear. The planet carrier has a hydrodynamic abutment on which the sun gear is configured to bear axially.

Abstract: A reduction gear for a turbomachine (6) extending around an axis (X-X) of rotation, comprising a ring gear (9) connected to a ring gear carrier (12), wherein the ring gear carrier (12) has, according to a section view along a plane including the axis (X-X), an internal segment (124), an external segment (126) and a ring gear support (128), extending successively from the internal shaft (122) until the ring gear support (128), the internal segment (124) extends until a radius R1 with respect to the axis (X-X), the external segment (126) forms an angle ? with the internal segment (124), the ring gear support (128) forms an angle ? with the external segment (126), and is secured to the ring gear (9) via a bolted connection accomplished at a nominal radius R2 with respect to the axis (X-X), in that the ratio R1/R2 is comprised between 0.3 and 0.7.

Abstract: 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.

Abstract: A lubricating oil distributor for a turbine engine mechanical reduction gear, for example of an aircraft, has an annular shape about an axis X and is formed of one single part. The distributor includes first and second independent oil circuits, the first oil circuit having a first oil inlet connected by a first annular chamber to several oil outlets distributed over a first circumference C1 about the axis X, and the second oil circuit having a second oil inlet connected by a second annular chamber to several oil outlets distributed over a second circumference C2 about the axis X, the first and second circumferences having different diameters.

Abstract: An impeller for a planet carrier of a epicyclic speed reduction gear of a turbine engine is fixed in rotation to the planet carrier and is rotatable about an axis of the reduction gear. The impeller has an annular shape about the axis and includes means for lubricating in particular planet gear bearings of the reduction gear. The lubricating means include an annular cavity located at the inner periphery of the impeller, wherein the impeller has an inner peripheral wall that closes the cavity in the radial direction. The impeller further includes an annular aperture that extends around the axis and opens in the axial direction into the cavity to supply lubricating oil thereto.

Abstract: A sun gear for a mechanical reduction gear of a turbine engine, in particular for aircraft, the sun gear having a general annular shape about an axis and comprising at the outer periphery thereof, a meshing gearing with planet gears of the reduction gear, and at the inner periphery thereof, splines for coupling with an input shaft of the reduction gear, characterised in that the sun gear has a staged profile in axial cross-section, and preferably comprises an annular recess opening radially inwards and configured to receive at least one oil jet.

Abstract: A ring gear for an epicyclic or planetary reduction gear of a turbomachine, in particular of an aircraft, said ring gear extending about an axis X and comprising first and second coaxial annular elements and comprising, respectively, two inner annular toothing sets of different orientation, each of said toothing sets having a pitch diameter and a median plane substantially perpendicular to said axis and with an intersection point designated Y in an axial cross-section of the ring gear, said first and second annular elements further comprising, respectively, first and second radially outer annular flanges for attaching said first and second elements to each other, wherein each of said first and second flanges comprises a peripheral portion extending in a plane that is angled with respect to said axis X and that passes substantially through said intersection point Y.

Abstract: An annular power transmission element with a longitudinal axis that has a first annular part, a second annular part with torque transmission means and a third annular part. The first, second and third annular parts are integral with each other. The first annular part and the third annular part are made of a first metallic material and the second annular part is made of a second metallic material having a density greater than the density of the first metallic material. The second annular part is locked longitudinally between the first annular part and the third annular part and radially on the first annular part, the first annular part is in contact with the third annular part and welded thereto.

Abstract: An impeller (130) for a planet carrier of a planetary gear speed reducer of a turbomachine, said impeller having a generally annular shape and comprising means (158) for supporting axes of rotation of planets of said reducer, said impeller comprising means for lubricating teeth of said planets and bearings of said axes, said lubrication means comprising an annular groove (138) located on the internal periphery of said impeller and opening radially towards the inside, said groove being connected to lubricant supply and/or spray means, characterised in that the impeller comprises dynamic annular sealing means (142, 144) located at the inner periphery of said impeller, on either side of the groove, and configured to interact with a stator (132) of the reducer or of the turbomachine intended to extend inside of and coaxially with the impeller.

Abstract: A mechanical gearbox for an aircraft turbomachine includes a sun gear having an axis (X) of rotation, a ring gear around the sun gear, and planet gears meshed with the sun gear and the ring gear. Each planet gear has a first toothing meshed with the sun gear and a second toothing meshed with the ring gear. The first toothing includes a series of upstream teeth and a series of downstream teeth located on either side of a plane (H) perpendicular to the axis (X) of rotation of the sun gear. The second toothing includes a series of upstream teeth and a series of downstream teeth located on either side of said plane (H) and separated from one another by said first toothing, these teeth being parallel to one another and to the axis (Y) of rotation of the planet gear.

Abstract: The invention relates to a pivot pin (5) for an epicyclic gear train sliding bearing, having axially opposed, laterally open circumferential grooves (25a) providing flexibility to the pivot pin, each groove having a radial width and at least one depth (P). At least one of the circumferential grooves (25a,25b) has a said width and/or depth (P) which varies circumferentially.

Abstract: The present invention relates to an oil transfer device (1) for lubricating a planet carrier, movable in rotation, of an epicyclic gear train for a turbomachine, the device (1) extending around an axis (A) and having: an annular casing (11) which extends around the axis (A), the casing (11) comprising a plurality of oil feed grooves (14), axially juxtaposed, each having an oil ejection opening configured to lead radially to a lubrication circuit of the planet carrier to be lubricated, the device (1) being characterized in that one of the oil feed grooves (14) is a high-pressure oil feed groove (14), called a high-pressure groove (14a), and another of the other oil feed grooves (14) is a low-pressure oil feed groove (14), called a low-pressure groove (14b), axially juxtaposed to the high-pressure groove (14a), the grooves (14) being arranged axially along the axis (X) so that the oil is able to be transferred axially from the high-pressure groove (14a) to the low-pressure groove (14b).

Abstract: Planet-carrier (10) for a reduction gear (6), in particular for a turbine engine of an aircraft, said planet-carrier comprising an annular cage extending about an axis X and comprising two radial annular walls (14a, 14b) extending about the axis X and connected at their outer periphery by means of first fins (14c), said radial walls being intended to be arranged opposite the planet gears (8) of the reduction gear, and said first fins defining between them the first assembly spaces (16) for these planet gears, characterised in that the planet-carrier is made of a single block and further comprises an attachment ring (15) that extends about the axis X and is connected to one of said walls by means of second fins (14d), said second fins defining between them second spaces (17a, 17b), separate from the first spaces (16), and of which at least some are intended to be intersected by lubrication pipes (20f, 21f) of the reduction gear.

Abstract: A power transmission mechanism for a turbomachine is provided, having a reduction gear having a first gear and a second gear having different reduction ratios and each having a first gear wheel mounted so as to be able to rotate freely on a shared first axle and a second gear wheel mounted on a shared second axle; and a coupling member having an annular body with an axis of revolution having first and second rows of helical coupling teeth, which are respectively oriented opposite and substantially parallel to the first and second directions, the coupling member being mounted so as to rotate with and slide axially on said first axle so as to occupy at least two predetermined axial meshing positions in which the coupling teeth mesh with complementary meshing projections of one of the first gear wheels which is then made to rotate with the first axle.

Abstract: A planet carrier for a speed-reducing unit with an epicyclic gear train for a turbine engine, said planet carrier comprising a cage defining an internal space for assembling a central sun gear having an axis of rotation and an annular row of planet gears disposed around the axis and meshed with said sun gear, said cage comprising two substantially parallel annular walls centered on said axis and a cylindrical wall connecting said annular walls to their outer periphery, a first one of said annular walls being connected to a substantially cylindrical body, wherein a second one of said annular walls is formed as a single part with a lubrication grove, channel or duct.

Abstract: The invention concerns a process for the assembly of an epicyclic or planetary gear train of a planet gear carrier comprising one or more bores, each of the bores being intended to receive a pivot (18), the process comprising the following steps: a) manufacturing of at least one pivot (18) comprising a real axis (46) distinct from a theoretical axis; b) measuring the position of a real axis of each of said one or more bores of the carrier; c) for each bore of the carrier, mounting a pivot (18) in said bore and orienting it angularly so that the eccentricity of the pivot (18) at least partially makes up for the eccentricity of said bore.