Some engines have flat steel plates attached to each end of the cylinder block. End plates add rigidity to the block and provide a mounting surface for parts such as gears, blowers, pumps, and generators. The type of plate that would attach to the cylinder block shown in figure 3-l is shown in figure 3-5.

BASES

In the majority of large engines, a base is used to support the cylinder block. The base shown in figure 3-6 is a welded-steel structure. Not only does the base support the cylinder block but it also provides a mounting surface for accessories to the engine and serves as a reservoir for the lubricating oil used by the engine. Many of the smaller engines do not have a separate base. Instead, they have an oil pan, which is secured directly to the bottom of the block. The block shown in figure 3-l uses such a pan. Usually, the oil pan serves only as the lower portion of the crankshaft housing and as an oil reservoir that collects and holds the oil.

SUMPS AND OIL PANS

A reservoir that is used for the collecting and holding of lubricating oil is a necessary part of

Figure 3-5.Front end plate on a cylinder block.

the structure of an engine. The reservoir may be called a sump or an oil pan, depending on the design of the engine. In most engines, the reservoir is usually attached directly to the engine. In dry sump engines, however, the oil pan merely catches the lubricating oil as the oil drains through the engine. As the lubricating oil reaches the oil pan, it immediately drains by gravity flow from the oil pan to a reservoir (that is located apart from the engine) where the lube oil for the engine is collected so it can be cooled and filtered. It is from this reservoir that the engine is supplied with lubricating oil and not from the oil pan. Thus, in dry sump engines, the oil pan remains essentially dry. Regardless of the design of the engine, the oil reservoir serves the same purpose wherever it is located.