🔍 Key Concepts

• Piston ring gas pressure loading in large, slow-speed diesels • How combustion pressure acts on the piston ring to force it against the liner • Where relative motion and contact pressure between ring and groove are greatest

💭 Think About

• Think about how gas pressure gets behind the piston ring and which surface of the groove it pushes the ring against during power stroke. • Consider which part of the ring groove actually guides the ring outward into contact with the cylinder liner under load. • Ask yourself: in normal operation, which groove surface experiences the most constant, high-pressure contact and sliding from the ring?

✅ Before You Answer

• Identify which groove surface the ring is forced against by combustion gas pressure during the power stroke. • Consider how inertia during direction changes (top to bottom of stroke) affects which face is loaded most of the time. • Eliminate any options that are not true contact/load-bearing surfaces between ring and groove in normal operation.