“It spins like a top” was the slogan used by the Adams-Farwell automobile company, as it was building its unique line of coaches around the turn of the 20th century. There are only three of these engines in existence, and you’re looking at the one surviving automobile of the breed.

The Adams-Farwell engine is a four-stroke rotary engine that used a unique frame-mounted vertical crankshaft, upon which the horizontally-mounted radial engine rotated. The five-cylinder engine has five exhaust pipes – one for each cylinder – that are mounted to the side of the air-cooled cylinders and spin with the engine.

The engine fires every other revolution like a traditional four-stroke, and the rotation of the engine assists in cooling the fins that are cast into the cylinders. The five-cylinder was rated at 50 horsepower, achieved through the use of a 5.500-inch bore and 5.000-inch stroke.

One interesting feature of the engine was the variable compression control valve, which permitted compression to be relieved during the starting sequence to ease the cranking process.

The crankcase consisted of two discs that sandwiched the cylinders, reducing size and weight. The top disc incorporated the intake pipe, while the bottom disc served as a mount for the beveled gear that carried the power to the transmission.

There are no valve springs – the valves themselves are operated by centrifugal force. The engine’s simple design allowed for easy repair – one could simply rotate it around to work on a particular cylinder, and the company claimed that the entire engine could be disassembled and removed from the car in one hour.

An interesting walk back in time – check it out!