This machine can be run independently as a DC motor or a DC generator. The armature, shunt field, and series field windings are terminated separately on the faceplate to permit long and short shunt as well as cumulatively and differentially compounded motor and generator connections. This machine is fitted with exposed movable brushes to allow students to study the effect of armature reaction and commutation while the machine is operating under load. An independent, circuit- breaker protected, shunt-field rheostat is mounted on the faceplate for motor speed control or generator output voltage adjustment.