Abstract: An eddy current retarder having a rotor part of the retarder with symmetry of revolution about the axis of the engine shaft so that it has a peripheral face facing a peripheral face of the stator part, the inductor of the retarder having at least one electromagnetic winding. Thus, the Eddy current retarder maintains a compact structure while at the same time allowing simple and easy control over its magnetic flux by virtue of the presence of electromagnets.

Abstract: The rotor or the stator of the apparatus has inductor coils whose respective axes are parallel to the axis of rotation and distributed at regular intervals along a circle centred on the axis of rotation. Each coil is traversed by a cylindrical pole core, one end of which is provided with a pole shoe of larger cross-section. An armature disc travels past these pole shoes with interposition of a gap. In relation to the direction of travel of the armature disc, each pole shoe offers an area which is larger in front than to the rear of the radial plane passing through the axis of rotation and through the axis of the corresponding coil. Each pole shoe has a rear edge of convex general shape in a plane parallel to the armature disc.