A controllable brake includes a rotor supported on one shaft end. The rotor is housed within a chamber containing a field controllable material which is acted upon by a magnetic field generator to change the rheology of the material and thereby impede movement of the rotor. The shaft is supported by two bearings which, in combination with the housing define a second housing chamber adapted to enclose means for monitoring and/or controlling the brake and in this way, an integrated, compact controllable brake is provided.