🔍 Key Concepts

• Thermal expansion of metal piston rings during engine operation • How piston ring gaps and clearances behave as temperature increases • What happens to a ring if there is no room for it to expand in the groove

💭 Think About

• As the engine reaches operating temperature, what happens to the length of the piston ring around its circumference? • If the ends of the ring were touching when cold, what mechanical problem could occur as the ring heats up and tries to expand? • Which option talks about preventing damage to the ring itself due to expansion, rather than about gas sealing or oil control?

✅ Before You Answer

• Distinguish between end clearance (gap at ring ends) and side clearance (space between ring sides and groove walls). • Identify which choices describe gas sealing functions and which describe mechanical protection of the ring. • Ask: Which function directly depends on the ring expanding in length and needing space at its ends?