GB832903A - Electric commutator or slip-ring brush - Google Patents

Abstract

832,903. Brushes for dynamo-electric machines. MORGAN CRUCIBLE CO. Ltd. May 25, 1956 [May 27, 1955; Aug. 31, 1955], Nos. 15414/55 and 25029/55. Class 35. In a split brush in which the brush-parts are not secured together, at least one part has a cap of different resistance so that the brush provides paths of different resistance. As shown in Fig. 3, two brush parts 11, 12 are provided with caps 21, 22 of different material mutually insulated by a strip 45. The parts may be pressed by a single spring 3, as shown, or by separate springs. Modifications have caps to which the brush parts make contact on oblique surfaces, the caps being recessed to prevent contact with the centre portion. In a further modification, Fig. 6, the cap 25 is extended down between the brush-parts 11, 12 to form a central brush-part. If desired additional caps of differential resistivity may be inserted at the top of the partbrushes 11, 12. A single part-brush in addition to the extended cap may be used so that the cap is L-shaped instead of T-shaped. Two partbrushes may be on the same side of this L-shaped brush. In Fig. 14, only the brush-part 12 has a cap 22 bonded to it. The flexible pigtail 31 may be connected to the brush 11, as shown, or to the cap 22, or to both. Two capped brushparts may be used, thus producing a triple brush. Fig. 11 shows how the brush part to which the pigtail 31 is attached has a step X so that both parts may be pulled up simultaneously. A modification is described in which the cap-part covers more than one brush-part, and pigtails are connected to the cap and a brush-part. The caps may be of graded resistance. Specification 832,904 is referred to.