🔍 Key Concepts

• Purpose of cylinder liners in large diesel engines • How lubricating oil films protect moving surfaces • Effect of a porous surface vs. smooth hard surface on oil retention

💭 Think About

• Think about what happens to the oil film on a very smooth, hard surface when the piston moves quickly up and down. • Which option describes a function that would directly help keep a stable layer of lubricating oil between the piston rings and liner? • Do any of the options claim to eliminate parts or problems that are normally still needed even with special liner coatings?

✅ Before You Answer

• Which choice directly mentions lubrication or oil film and not strength or wear alone? • Ask yourself if chromium alone can prevent ring wear or make scraper rings unnecessary, based on what you know about engine design. • Consider whether small surface pores would be more likely to hold oil in place or to weaken the metal.