Mechanical reduction gear for an aircraft turbine engine

A mechanical reduction gear of a turbine engine, the mechanical reduction gear comprising:

• a sun gear having a first axis (X) of rotation and comprising an external toothing;
• a ring gear which extends around the sun gear and which comprises an internal toothing;
• planet gears which are in mesh with the sun gear and the ring gear and which each comprise a first toothing which has a first average diameter and which is in mesh with the external toothing of the sun gear and a second toothing which has a second average diameter and which is in mesh with the internal toothing of the ring gear, said second average diameter of the second toothing being different from said first average diameter of the first toothing;
• a planet carrier which supports bearings for guiding the planet gears in rotation around second axes (Y) parallel to the first axis (X);
• and
• a lubrication circuit of the mechanical reduction gear,
• wherein the planet carrier comprises at least one axial abutment which comprises a bearing surface on which said sun gear is configured to bear axially in operation, said lubrication circuit comprising:
• an annular film of oil between the bearing surface and the sun gear, and
• at least one channel configured to convey oil to said annular film of oil.