Working model of an NSU Wankel rotary engine, sectioned.

This is a model of a Wankel rotary piston engine. The original engine was developed by Felix Wankel in Germany during the 1950s. Between 1965 and 1975 over a million Wankel engines were made around the world. Many of these were used in motor cars, but some were also fitted to motor cycles, boats and aircraft. Instead of a piston moving up and down in a cylinder, as in a conventional motor-car engine, the Wankel engine has a triangular rotor which revolves in a closely-fitting crank-case. The rotor is the only moving part in the engine, and spins at very high speeds. The object on display is one of a series of simple educational models specially designed to show how various types of engine operate.