LO 10-1 Explain the purpose, function, and operating principles of diesel engine lubrication systems

1. Evolving Lubrication System Technology

Evolving Lubrication System Technology

Engine oil, an essential component of the lubrication system, is a substance with which every working technician has almost daily contact. It is also the most frequently inspected and serviced item in a commercial vehicle engine, ranging from daily level checks and regularly scheduled drain intervals to sampling for oil analysis. Oil and the lubrication system are essential to a running engine to prevent rapid failure. Friction produced by moving engine parts at high speed under load for even a few minutes can generate enough heat to melt and severely damage engine parts Figure 1. Without lubricant to minimize the effects of friction, the engine would be quickly destroyed, seize, or both. The lubrication system performs not only the obvious requirement to reduce friction between moving parts but also is essential for cooling, cleaning, corrosion protection, sealing piston rings, and absorbing shock loads inside the engine (Figure 2 and Figure 3) . Lubrication system technology does not stand still; changing engine technology and oil performance specifications always go together. The evolution of engine oil and lubrication systems is driven by the rapid movement to cleaner, more fuel-efficient diesel engines, which require better oils and lubrication systems to protect them. Today’s diesels also have to meet new demands imposed by emissions legislation in addition to increased durability requirements. Oils now need to be compatible with the latest exhaust aftertreatment systems and use of biofuels while meeting customers’ expectations for longer oil drain intervals to reduce operating costs. Frictional losses in engines also represent a sizable fraction of the fuel energy savings targeted by greenhouse gas (GHG) standards. Fuel consumption is reduced by new oils and lubrication system features that decrease engine friction and the energy previously needed to circulate lubricating oil.

FIGURE 10-1: This crankshaft journal was damaged because of lack of lubrication. The oil feed hole is plugged with bearing material, which melted during engine operation.

FIGURE 10-2: Observed at a microscopic level, even the smoothest metal parts have irregular surfaces. Metal-to-metal contact produces friction and wear. Friction between moving parts quickly generates heat.

FIGURE 10-3: Lubrication between moving parts separates the parts with a slippery film. Friction and heat are minimized, which extends the durability of the metal surfaces.

In this chapter, the function and construction of the lubrication system is examined, as is an explanation about how all the parts operate together to perform the various tasks required of the lubrication system. A thorough knowledge of the operation of the lubrication system will assist the repair technician not only in making correct recommendations for service and maintenance of this important engine system but also in providing the background information needed to properly diagnose and repair lubrication systems to ensure reliable engine operation and maximum engine durability.