The Mercedes D.III, or F1466 as it was known internally, was a six-cylinder SOHC valvetrain liquid-cooled inline aircraft engine built by Daimler and used on a wide variety of German aircraft during World War I. The initial versions were introduced in 1914 at 120 kW (160 hp), but a series of changes improved this to 130 kW (170 hp) in 1917, and 130 kW (180 hp) by mid-1918. These later models were used on almost all late-war German fighters, and its only real competition, the BMW III, was available only in very limited numbers. Compared to the Allied engines it faced, the D.III was generally outdated.
Mercedes D.III
Original 120 kW (160 hp) Mercedes D.III, with "side-slot" rocker-arm design SOHC valvetrain atop the cylinders.
Aft-end details of the original SOHC valvetrain for the D.III - the rocker arm emerges from the "rocker box" through a slot in the box's side.
Later pattern SOHC D.III valvetrain, using the relocated rocker box design, with rotary shafts to operate the fully exposed roller rocker arms.
An overhead camshaft (OHC) engine is a piston engine in which the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion chamber in the engine block.
OHC cylinder head (for a 1987 Honda D15A3 engine)
SOHC design (for a 1973 Triumph Dolomite Sprint)
DOHC design (for a V12 engine)
Rubber timing belt during installation