Motor-tachometer

Claim 1

A combined motor and tachometer comprising a drive shaft, separate motor and tachometer armatures mounted in axially spaced relation on said shaft, motor housing means surrounding said armatures and rotationally supporting said shaft, a pair of correspondingly spaced fields associated with said housing means one each for each of said armatures, a drum-type motor commutator on said shaft positioned in the space between said armatures adjacent said motor armature and having an axial commutating surface, disk-type tachometer commutator on said shaft in the space between said armatures positioned adjacent said tachometer armature and being formed with a radial commutating surface, said radial surface facing away from said axial commutating surface and toward said tachometer armature, and said tachometer commutator being formed with a radial diameter which exceeds the diameter of said motor commutator for isolating, and providing mechanical protection of, said tachometer commutator from said motor commutator, said tachometer field including a permanent magnet in surrounding relation to said tachometer, a combined magnet retainer and brush holder having an encircling yoke portion supporting said magnet and further having a pair of axially extending brush holder portions, means mounting said retainer on said housing at said brush holder portions, and means in said brush holder portions slidably receiving a corresponding pair of axially movable brushes for coaction with the radial face of said tachometer commutator.