One of the most versatile small German military vehicles, the Kettenkrad, a blend of a tractor and a motorcycle, was powered with a 1.4 L Olympia four-cylinder engine. Produced by NSU, it had motorcycle-type front-wheel steering for gentle turns and negotiated tight corners with brakes on the propelling caterpillar tracks. The Kettenkrad towed antitank guns and transported troops and signal gear in several theatres of war. NSU continued to make it after the war for use in mines and forests. It was one of the few vehicles that could do jobs formerly performed by horses for which, owing to the shortage of oats, even less fuel was available than for motor vehicles.
It had some crazy mechanical issues. At one point it stumbled and stalled because the carburetor had come loose from the intake manifold and I had to tighten it back down! Another time, my brother was driving it and the brakes failed. Somehow the end of the brake shoe that meets the brake cylinder piston had become worn on one side, causing the piston to slip off the end of the shoe when the brakes were applied, losing braking and squirting fluid all over.