Abstract: A radio-frequency interference suppressing system for inside a permanent magnet field motor case includes a pair of commutator brushes, a pair of power input terminals electrically connected with the brushes, a capacitor electrically connected across the terminals, a pair of capacitors each electrically connected to a different one of the two terminals, and a grounding member electrically connected with the pair of capacitors for engaging the inside of the motor case.

Abstract: The permanent magnet fields encircling the armature of a direct current motor are encircled by a pair of radially spaced cylindrical metal members separated by a cylindrical dielectric member. One of the metal members and one of the brushes that engages the commutator of the motor are grounded. The other brush and the other cylindrical metal member are connected to a direct current power supply, whereby a capacitor is formed by the three cylindrical members for suppressing radio frequency noise generated by sparking of the brushes at the commutator.

Abstract: A frame that has a central opening through it for the commutator of an electric motor is provided with a pair of brush housings, each having a passage therethrough in which a brush is slidable. One side of each housing is provided with a longitudinal slot, beside which a stud projects from the frame. The central coil of a torsion spring encircles the stud and has end portions extending laterally toward the housing, with the free ends of the spring biased toward each other. One end of the spring engages an abutment at the inner end of the housing and the opposite end of the spring extends through the housing slot and into a notch in the side of the brush to hold the brush retracted in the housing passage until the end of the spring is removed from the notch and placed against the outer end of the brush to move the inner end of the brush into commutator-engaging position.

Abstract: An electric motor frame has a brush-receiving recess beside the commutator. The recess has top and bottom walls and an insulating brush housing is disposed in the recess where it is held in fixed position. Slidable lengthwise in the housing is a brush, between one side of which and the housing there is a stationary metal strip that extends substantially full length of the housing and has an outer end portion extending transversely of the brush. Compressed between this end portion of the strip and the brush is a coil spring that holds the brush against the commutator. An electrical conductor engages the strip, while a flexible wire electrically connects the strip with the brush. The brush housing is provided with at least one exterior rib extending lengthwise of it, and one of the walls of the frame recess has a groove in it that snugly receives the rib to accurately position the housing in the frame.