Schematic drawing of a straight-four engine
Mercedes D.IIIs on a WW1 AEG G.IV
Inverted Gipsy Major in a DHA-3 Drover
Straight-4 engine in an Indian Four motorcycle
The straight engine (also called inline engine) is a configuration of multi-cylinder piston engine where all of the cylinders are arranged in a single row, rather than radially or in two or more cylinder banks.