Abstract: A structure for retaining a cartridge brush holder in a dynamoelectric machine having a tubular frame member having a smooth curved inner surface and an outer surface is shown, including an aperture adapted to receive a generally cylindrical body of said cartridge brush holders through the frame member, the body of the cartridge brush holder being installed through the aperture with its flange adjacent the outer surface. A plano-convex member having a first convex surface and a second flat surface and having a bore therethrough receives the body of the cartridge bursh holder. A spring washer is placed over the cylindrical body of the brush holder, and retained by a retaining ring means pressed over the cylindrical body of the brush holder adjacent the spring washer to compress the spring washer to retain the brush holder in the tubular frame member.