Hall sensor brushless dc motor is used for reversing, the traditional have a dc motor is through the carbon brush and commutator mechanical commutation, the advantage of the brushless dc motor is a brushless dc motor in the process of reversing did not produce sparks, and ordinary brush motor has a small number of sparks produced in the process of commutation; Brushless dc motor life generally between tens of thousands of hours, and ordinary life in 1000 - of brush motor2000 hours;