Patent ID: 11296575

Abstract:
An electric machine having a field coil and a rotatable armature coil. A rotatable commutator is conductively coupled with the armature coil and has a plurality of contacts. A plurality of brushes are conductively engageable with the plurality of contacts wherein rotation of commutator about the rotational axis causes the plurality of contacts to sequentially engage the plurality of brushes as the plurality of contacts rotate about the rotational axis. The plurality of brushes includes at least one positive brush and at least one negative brush, the at least one positive brush being a multi-layer brush and the negative brush being a single layer block brush. The multi-layer brush may include a high-copper layer and a low-copper layer with the low-copper layer forming the trailing edge of the brush. The single layer brush may have a copper content greater than the high-copper layer of the multi-layer brush.