Abstract: An electromagnetic brake comprises a plurality of electromagnetic coils disposed on a stationary part of a drive force supply unit and producing a magnetic field in response to energizing currents supplied thereto, a rotor made of a conductive material and disposed on a rotary shaft of the drive force supply unit and positioned so as to rotate in the magnetic field and produce an eddy current in the rotor. The eddy current converts the rotational energy imparted to the rotor through the shaft into heat and generates a breaking force. A switching unit connected to the electromagnetic coils selectively controls the flow of energizing current to the coils in accordance with switching data supplied thereto by a control unit, responsive to external control data, for selectively controlling the ON/OFF ratio of energizing current flow to the electromagnetic coils.

Abstract: A wheel cylinder for drum brakes having a mechanism for automatically adjusting the excess clearance formed between the lining on each brake shoe and the inner surface of the brake drum due to the wear of the lining. Excess clearance may be produced in different amounts by the respective (two) brake shoes. The wheel cylinder of this invention has incorporated in its cylinder body a mechanism for adjusting such excess clearance caused by each of the brake shoes. There are provided guide gears designed to rotate in accordance with piston movement and clutches making ratchet engagement with the guide gears, and the excess clearance is adjusted by the axial movement of each piston corresponding to the angle of rotation made by a new ratchet engagement. Also, clamps are provided between the brake shoes for ensuring the correct amount of piston movement corresponding to the angle of rotation. The present wheel cylinder finds best application to drum brakes for vehicles.