A power unit for use with a motorized cart. Two wheels are rotatably mounted to opposite ends of an interconnecting member. In one embodiment, at least one driving motor is housed in at least one of these two wheels. In another embodiment, a driving motor is housed in one of the two wheels, and batteries are housed in the other wheel. In a further embodiment, two opposite platforms are mounted over the interconnecting member in a spaced relation to each other. In yet another embodiment, a battery-accommodating portion is disposed between the two platforms. Batteries are housed in the battery-accommodating portion. Where the cart is a golf cart, the motor and the batteries are concealed from view in every embodiment of the invention. This is favorable from an aesthetical point of view. Furthermore, the space in at least one wheel can be effectively utilized. Where the frame of the golf cart is foldable, it is easy to store and transport the cart.

A wheel assembly for a wheelchair includes a mounting plate fixed on one side of the seat portion, a motor and a gear unit which includes a gear disc, and a gear shaft that extends through the gear disc. The motor includes a driving worm fixed on the motor shaft so as to mesh with the gear disc. The gear disc is formed with an engaging recess. The gear shaft carries a slidable transverse key thereon. A spring biases the gear shaft to engage the key in the recess. A driving gear is fixed on the gear shaft. A driven gear is mounted rotatably on the mounting plate and is fastened to a wheel. A chain interconnects the driving gear and the driven gear. A hand lever can be moved against the bias action of the spring so as to disengage the key from the recess of the gear disc.

A wheelchair has a seat portion and a pair of stationary mounting plates fixed to two sides of the seat portion. Each of the mounting plates has a driven pulley rotatably mounted thereon and a driving unit with a driving pulley. An endless belt interconnects the driving and driven pulleys together. A clutch assembly is mounted on the mounting plate and is associated with the driving unit to engage and disengage the driving unit from a pair of wheels that are attached to the stationary mounting plates.

A wheeled vehicle, in particular a two-wheeler, is provided with a frame supported by running wheels, with an electromotor, for driving at least one of the running wheels, and with at least one battery provided on the frame for supplying energy to the electromotor, characterized in that the battery is disposed near the wheel hub of one of the wheels.

Motorized wheels in a wheelchair or other light vehicle are each mounted on an axle for limited rotation relative to a secondary connection to the frame of the vehicle which incorporates a sensor providing feedback which controls the motor according to torque sensed through the secondary connection. The motor and associated gearing and control circuitry are housed within a wheel hub of which a drum supporting a wheel rim is supported at its inner surface on multiple bearings spaced around its periphery.