Vehicle transmission system fitted with an electrical retarder

A transmission system for a self-propelled land vehicle, the transmission system comprising a shaft rotatable about an axis together with an electrical eddy current retarder itself comprising an annular inductor stator and a rotor, said rotor including at least one wheel secured to the shaft, which at least one wheel includes a ring-shaped core that heats and is subjected to thermal expansion during operation of the retarder, and that itself includes an annular core disk of ferromagnetic material, said core disk being disposed facing the stator and being secured to a plurality of blades forming cooling fins, said at least one wheel further including at least three fixing arms each extending inwards from an outer end secured to the ring-shaped core to an inner end connected to the shaft,

• wherein the inner end of each fixing arm is connected to the shaft by means of a metal tongue which is flat in the radial direction and which extends longitudinally parallel to the axis of rotation at least between a metal tongue fixing zone secured to the shaft and a free end fixed to the inner end of the fixing arm in question, each metal tongue being elastically deformable in the radial direction when the core ring is subjected to thermal expansion.