The aim of this work, consisting of 9 individual, self-contained booklets, is to describe commercial vehicle technology in a concise and illustrative way. Compact and easy to understand, it provides an overview of the technology that goes into modern commercial vehicles. Content of this volume: This volume, The Diesel Engine, provides an overview of the vast topic of diesel engines. It offers basic information about the mechanical functioning of the engine. The integration of the engine into the vehicle and major systems such as the cooling system, the fuel system and the exhaust gas aftertreatment system are explained so that readers in training and in a practical setting may gain an understanding of the diesel engine. A chapter on thermodynamics rounds off the book.