Electromagnetic Retarder and Assembly Comprising Such a Retarder

An assembly comprising a rotational driving mechanism of a drive shaft, and an electromagnetic retarder capable of slowing down the rotation of the drive shaft, the driving mechanism comprising a housing and a drive shaft that is capable of pivoting around an axis of rotation extending along an axial direction, said electromagnetic retarder comprising a rotor fixed to the drive shaft, a stator support fixed to the housing, and a stator integral with the stator support, wherein the stator support comprises at least one relief extending along the axial direction, and in that the housing comprises at least one stud provided with an attachment hole configured to fix the stator support to the housing and at least one complementary relief cooperating with at least part of the relief of the stator support to fix the position of the stator support in relation to the housing along at least one direction contained in a plane perpendicular to the axial direction, said complementary relief being a projection extending in the extension of a cylindrical face of the at least one stud.