PRINCIPAL STATIONARY PARTS OF AN ENGINE

Most internal-combustion engines of the reciprocating type are constructed in the same general pattern. Although engines are not exactly alike, there are certain features common to all of them and the main parts of most engines are similarly arranged. Gasoline engines and diesel engines have the same basic structure; therefore, the descriptions of the engine parts and systems in this rate training manual will apply generally to both types of engines. However, differences do exist and we will point these out wherever they occur. The main differences in diesel and gasoline engines exist in the fuel systems and the methods of ignition.

The main parts of an engine, excluding accessories and systems, may be divided into two principal groups: (1) those parts that do not involve motion, such as the structural frame and its components and related parts; and (2) those parts that involve motion. This chapter deals with the main stationary parts of an engine. Information about the moving parts of an engine will be given in the chapters that follow. After reading this chapter, you should be able to identify the principal stationary parts of an engine in terms of basic design, location, and function. The stationary parts of an engine maintain the moving parts in their proper relative position so that the gas pressure produced by combustion can push the pistons and rotate the crankshaft. The prime requirements for the stationary parts of Navy diesel engines are ample strength, low weight, minimum size, and simplicity of design.

Ample strength is necessary if the parts are to withstand the extreme forces that are developed within the engine. Space limitations aboard ship make minimum weight and size essential. Simplicity of design is of great importance when maintenance and overhaul procedures are performed.