Aircraft engine Mercedes D.IV

The D.IV was the first mass-produced German engine to be equipped with a reduction gear mechanism to drive the propeller. This engine also represents a first attempt of Daimler to develop an eight-in-line engine.The engine overcame the acceptance test in December of 1915, but it was produced in only 429 copies because of its poor reliability, mainly due to the fragility of the crankshaft which tended to break for its excessive length.