The Siemens-Halske Sh.III was an 11-cylinder, air-cooled counter rotary engine developed in Germany during World War I.

[1] The crankshaft was driven at 900 rpm via a set of bevel gears, located at the back of the engine, with a 2:1 ratio.

The cylinders and propeller would have rotated at a speed of 1800 rpm anti-clockwise had the crankshaft been fixed.

[1] Additional benefits of the counter rotary design were lower aerodynamic losses[1] and reduced gyroscopic forces as the net cylinder rotational speed was reduced when compared to a conventional rotary of similar power output.

The engine tended to overheat as the relatively slow rotation of the cylinders limited cooling air flow.