Abstract: A brush assembly (100) for a slip ring assembly of a rotating electrical machine, having at a brush holder (120) defining a cage into which a brush (103) slides; and a rod (101) extending along a second axis (D2) parallel to the first axis, for supporting the brush holder. One of the rod and the brush holder defines a recess (121), the other has a portion sized to be received into the recess the mating portion (105), the recess defined by a first wall (123, 124) disposed for abutment against the mating portion when, the mating portion received in the recess, the brush holder is driven longitudinally along the rod parallel to the second axis. The recess is defined by a second wall (122) disposed for abutment against mating portion when, the mating portion received in the recess, the brush holder is driven tangentially around the second axis.