NEXT BIG THING
IN WHEEL MOTORS
WORDS: PAUL HORRELL
IN WHEEL MOTORS ARE ON THE VERGE of real applications. That’s a terrible pun: the Verge motorcycle has one. It looks dramatic, with no central hub or axle. Verge is part of Donut Lab, a Finnish builder of motors in the shape of donuts.
The idea is wonderfully simple. A normal motor’s rotor, the spinning bit, is inside, with its output shaft emerging from the centre. The stator, the coil windings that don’t turn, is fixed to the outer casing. A wheel motor flips that layout inside out. The rotor is on the outside diameter, in unit with the wheel rim and so driving it. The stator is fixed to the suspension. The large diameter means much more torque than usual, so there’s no need for the reduction gears that come with inboard motors.