First Four Stroke Engine

The first practical "four-stroke" engine was patented by the Otto and Langen Company of Deutz, Germany.

A1-intake valve
A2-piston
A3-fuel/air mixture
A4-cylinder
B1-spark plug
B2-compressed mixture
C1-mixture ignites
D1-exhaust valve
D2-burned gases

Nikolaus Otto was a salesman with a grocer when he read of Lenoir's two-stroke gas-driven internal combustion engine. Otto started a workshop in Deutz near Cologne, supported by Langen in 1863. He had a model engine built and improved upon the gas engine, making it a practical power source. The four-stroke Otto Engine was invented in 1876, and a large number of engines were produced under the patent of Otto and Langen.

It was however, a German engineer named Gottlieb Daimler, who, carried out much of the development work on the engine. Daimler was at the time employed with Otto and Langen, and a substantial credit for the success is due to him.