brush as an important part of dc motor controller, use wear over time will happen. If wear serious, need to be replaced. 1. Because of the different types of brush hardness and current density is different, so the change when you choose the same type of brush. 2. When change the double brush, pay attention to the change of sequence, cant agree, prevent brush to beat, affect the reversing. 3. When replacing a single brush can be put into use directly without grinding, but if the same more than two brush brush arm need to change, is the need for grinding. 4. Change, will the new brush grinding into the radian of like the old brush size.