US Patent 7276833 Electromagnetic retarder system and method

An electromagnetic retarder system is disclosed. In one embodiment, the retarder system comprises: a shaft; a coil statically disposed on the shaft and having a hollow cylindrical shape; a yoke statically disposed on the shaft, the yoke having a first cylindrical surface and a second cylindrical surface, the second cylindrical surface disposed coaxial with said coil; at least one claw pole rotor mounted on the shaft, the at least one claw pole rotor formed of magnetic half wheels that taper into claws; and an induction drum disposed coaxial with the shaft and mounted so as to encompass the coil, the yoke and the at least one rotor.