Brush holders are used to hold the brush in position. Brush holders are used in DC motors as well as in AC slip ring motors. The function of a brush holder is to hold the brush at the proper angle and position. The brush holder should also ensure that the brush rests on the commutator with the correct pressure. if the contact pressure is too high, the brush can get worn out faster. If the contact pressure is too low, arcing may result.
Modern brush holders have markings which indicate the extent of wear on the brush. The height of the brushes can be adjusted. Quick disconnect terminals in modern brush holders make replacing carbon brushes easier and quicker.