A drive mechanism for a vehicle is disclosed, said drive mechanism converting the reciprocating clockwise-counterclockwise motion of an input shaft into continuous rotation of an output shaft by means of two one-way clutches mechanically coupled to the input shaft and the output shaft, said one-way clutches having their power stroke in opposite directions of rotation. In an embodiment, said drive mechanism can be contained in a wheel hub and used for human-powered vehicles such as scooters, bicycles, wheelchairs, rollerskates, or other vehicles.