Trimming Brushes

—At certain intervals, according to the care taken to reduce sparking, and the length of time the machine runs, the brushes will fray out or wear unevenly, and will therefore need trimming. They should then be removed from the brush holders, and their contact ends or faces examined. If not truly square, they should be filed or clipped with a pair of shears, the course of treatment differing with the type of brush. If metal strip brushes, the feathered-out ends should be clipped square with a pair of shears, the ends thoroughlyfcleaned from any dirt or carbonized oil, and replaced in their holders. Gauze and wire brushes require a little more attention. When their position on the commutator has been well adjusted and looked after, so that little or no sparking has taken place, it will generally be found only nece ary to wipe them clean, and clip off the fringed edges and corners with the shears, or a pair gy sci ors. If, however, the machine has been sparking, the faces will be worn or burnt away, and probably fused. If such is the case, they will need to be put in the filing clamp, and filed up square and true, as directed above. If the contact faces of the brushes are very dirty and covered with a coating of carbonized oil, ete., it will be nece ary to clean them with benzoline or soda solution before replacing.