Abstract: An eddy current type brake system connected to an output shaft of a transmission of a vehicle comprises a rotor connected to the transmission shaft, a stator movable relative to the rotor and a magnet mounted on the stator. The rotor has a ferromagnetic part and a non-magnetic or feeble-magnetic part. The magnet of the stator can move into the vicinity of the ferromagnetic part of the rotor to allow an eddy current to flow in the rotor. The magnet also can move into the vicinity of the non-magnetic or feeble-magnetic part of the rotor to prevent the eddy current from reaching the rotor. Therefore, when the magnet is moved into the vicinity of the ferromagnetic part, a brake force is applied to the rotor due to the eddy current whereas when the magnet is moved into the vicinity of the non-magnetic or feeble-magnetic part, the brake force is no longer applied to the rotor.

Abstract: A rotor for an eddy current type retarder produces a brake force by producing eddy current using magnets mounted on a stationary member of the retarder. The rotor is mounted on a rotatable shaft and faces the magnets. The base member is made from a material containing steel. A thin film is formed on that face of the base member which faces the magnets. The film is made from a material containing rust-preventative material. A plurality of fins are formed on the base member by casting, using a material of good castability, with the base member as an insert. The rotor can be manufactured inexpensively and has the same characteristics as a rotor made from low-carbon-made steel.

Abstract: An eddy current type brake system adapted to a vehicle comprises a drum-like rotor mounted on an output shaft of a transmission of the vehicle, a stator provided in the rotor and being able to reciprocate in an axial direction of the rotor, a plurality of permanent magnets mounted on the stator, a brake force producing device provided between the stator and the rotor for magnetically connecting the permanent magnets of the stator with the rotor to apply brake force to the rotor, and a device for magnetically cutting the permanent magnets of the stator from the rotor to release the brake force from the rotor. When the stator is moved to a position to face the brake force producing device, the permanent magnets of the stator are connected to the rotor magnetically and the eddy current is produced in the rotor so that the rotating shaft is decelerated.