"220V Cooling Fan" is to provide the use of a DC power source: DC motor stator and rotor two major components, there is a stator pole (winding or permanent magnet), rotor windings, the power, the rotor is also formed on the magnetic field ( pole), there is an angle between the stator and the rotor poles, "220V Cooling Fan" in the rotor magnetic field (N and S poles between) mutual attraction, the motor rotation. Change the brush seat, you can change the angle between the rotor and stator poles (assuming that is the angle between the stator pole starting side, "220V Cooling Fan" to the other side of the rotor poles, the rotor poles pointing in the direction of the stator poles is direction of rotation) direction, thereby changing the direction of rotation of the motor.