Abstract: A two-piece housing having a base section and a closure section, is mounted on a motor or other machine having a projecting shaft, and the housing encloses a series of annular brake discs mounted on a hub member which receives the shaft. The discs interfit between a series of non-rotating annular brake plates supported by the base section of the housing, and the hub member is also effective to circulate cooling oil within the housing and outwardly between the plates and discs. A non-rotating annular thrust plate and a set of circumferentially spaced springs are located adjacent the base section and compress the plates and discs together and against the closure section for braking the shaft. A set of circumferentially spaced solenoids are mounted on the closure housing section and have corresponding armature rods or members which extend axially into the housing to push the thrust plate against the springs when the solenoids are energized to release the plates and discs.