They use a slipring. In some ways, its kind of ironic, because these are now most prevalent in brushless DC motors. Slip rings work in the same fashion as bru

They use a slipring. In some ways, its kind of ironic, because these are now most prevalent in brushless DC motors. Slip rings work in the same fashion as brushed motors. To achieve continuous rotation in a brushed motor, there are carbon brushes that are closing different circuits as the rotor spins. This allows the phase of the electricity to stay constantly ahead of the phase of the motor, giving it its acceleration. In a brushless DC motor, this same effect is achieved through a feedback loop, obviating the need for the brushes, which wear over time, and leave carbon deposits. https://www.sparkfun.com/products/13064 https://www.sparkfun.com/products/13064