Abstract: A mechanical reducer for a turbomachine, in particular for an aircraft, this reducer including a sun gear, a ring gear, planet gears which are meshed with the sun gear and the ring gear, hydrodynamic bearings for guiding the planet gears in rotation, these hydrodynamic bearings being carried by a planet carrier and including cylindrical bodies which include an internal oil circulation cavity and first pipelines for conveying oil from this cavity to at least one external cylindrical surface of the body, wherein each of the cylindrical bodies further includes second oil evacuation pipelines, which are different from the first pipelines, and which extend from said at least one external cylindrical surface to at least one of the longitudinal ends of that body.

Abstract: A drive assembly for a mechanical reducer for a turbomachine, in particular for an aircraft, includes planet gears, a planet carrier having at least one transverse wall, plain bearings for guiding the planet gears in rotation, and an oil supply circuit for the plain bearings. The planet carrier has collars for attaching the planet gears to the at least one transverse wall, and each of the planet gears includes at least one external cylindrical surface for forming an oil film with an internal cylindrical surface portion of each of the collars for forming said oil film.