One of Germany's premier engine manufacturers, Junkers produced a unique range of aero engines before and after WW", and their 'Jumo' range of diesels was recognised a being one of the landmark engines in aviation.
What set these engines apart from other designs, was the unusual Junkers Layout of opposed pistons in common cylinders, and twin crankshafts with a synchronising geartrain to keep all the pistons in the right place at the right time !