🔍 Key Concepts

• Function of oil control (oil scraper) rings on diesel pistons • How oil is returned to the crankcase and kept off the cylinder ports in two-stroke engines • Relationship between piston position, ports, and ring grooves in a uniflow or loop-scavenged two-stroke diesel

💭 Think About

• Think about where the intake/scavenge ports are located in the cylinder and what parts of the piston move past them. • Which ring position (high, middle, or low on the piston) will be most effective at scraping excess oil down before it can reach the ports? • Which option focuses on location of oil rings rather than ring material or ring width?

✅ Before You Answer

• Identify which choice deals specifically with oil ring location rather than ring type or material. • Visualize the relative height of the ports versus the piston skirt and pin — where must the oil ring sit to intercept oil before it reaches the ports? • Ask: which configuration best helps scrape oil down and away from the port openings during the stroke?