An electric motor includes a chassis having a front tube to rotatably support a handle, two arms each having one end pivotally attached to the chassis to support two front wheels on the outer ends. A cushioning device may be used to cushion the front wheels and the arms relative to the chassis. A carrier is pivotally attached to the rear portion of the chassis, and includes a spindle to support two rear wheels. An electric motor device is attached to the carrier to drive the rear wheels. Another cushioning device may be used to cushion the rear wheels and the carrier relative to the chassis.