It was an oscillating mechanism involving an extra wheel, as compared with the verge-and-foliot system.

The point of that extra wheel though is not novelty but stability and safety.

Co-Cos are most suited to freight work as the extra wheels give them good traction.

Driving extra wheels meant more drive train weight, in turn requiring a larger and heavier engine to maintain performance.

Its drivetrain featured an extra wheel to improve off-road capabilities, and the hull was wider.

With these extra wheels, I can haul anything we find.

It also had an extra wheel put on each side which lowered its center of gravity to prevent flipping.

She did not have to explain to this audience what the sandbags and extra wheels meant.

The rider sits on and operates these vehicles like a motorcycle, but the extra wheels give more stability at slower speeds.

Which ones belong in the record books for their exceptional dimensions, their extra wheels, their low price?