🔍 Key Concepts

• Piston ring land function and stresses on a low-speed diesel piston • Effect of clearance between ring and groove on mechanical loading • Differences between problems caused by lubricating oil condition/temperature vs. purely mechanical fit issues

💭 Think About

• Think about which option would directly increase mechanical stress and gas pressure loading on the metal area between the grooves rather than just affecting lubrication quality. • Consider what happens to a piston ring as it heats, expands, and moves in its groove at top dead center and during combustion. • Ask yourself: which condition would most likely prevent the ring from moving freely and transferring forces smoothly, leading to localized stress and potential cracking?

✅ Before You Answer

• Identify which choice most directly affects ring movement and clearance in the groove itself. • Distinguish between conditions that mainly lead to wear and lubrication breakdown versus those that create binding or metal-to-metal wedging. • Verify in your engine theory notes how too little clearance vs. oil contamination or temperature typically show up as different failure modes (scuffing, wear, vs. cracking of ring lands).