The chariot was a small vehicle, carried on a single axle, drawn by two horses.
Also drawn on a single axle, also open to the rear.
The single non-drive axle was therefore mounted right at the front of the locomotive.
Each engine powered a single axle of the locomotive.
Truck designs will use such a configuration to provide a greater weight capacity than a single axle.
A very short wheelbase, usually with a solidly mounted single rear axle.
The rear single axle remained as it was.
They were quickly rebuilt as 4-4-0Ts due to trouble with the single leading axle.
The 9000 Series is of a conventional layout, with single or tandem rear axles.
The sprockets are attached onto a single axle which allows them to turn at the same time.