With over 12,000 units produced, the D III and further developed D IIIa recorded the highest production volume of all aero engines during World War I. The reasons for the great military demand were the engines high level of reliability and its advanced design. Among other things, the 6-cylinder inline engine featured steel cylinders and an overhead camshaft wih a vertical shaft drive.
6-cylinders, 14,778cc, 170-horsepower @ 1450 RPM
Design and developmen
Details of the original SOHC valvetrain for the German Mercedes D.III - note the rocker arm emerging from the "rocker box" through a slot in the box's side.
Details of the later pattern SOHC Mercedes D.III valvetrain, using the relocated rocker box design, with rotary shafts to operate the fully-exposed rocker arms.