🔍 Key Concepts

• Piston compression rings vs. oil control rings and what each type is designed to do • How combustion gas pressure interacts with the piston and cylinder liner • Why a tight gas seal is important for engine efficiency and safety

💭 Think About

• Ask yourself: What problem would occur if high‑pressure combustion gases could easily leak past the piston into the crankcase? • Which choice most directly relates to containing or controlling combustion pressure rather than lubrication or wear reduction? • Think about the name: "compression" ring. What part of the engine cycle is that referring to, and what must be maintained during that part?

✅ Before You Answer

• Identify which option directly describes sealing combustion pressure between piston and liner • Distinguish between gas sealing and lubricating oil control—they are related but not the same function • Eliminate any options that sound more like secondary benefits (side effects) rather than the primary design purpose of a compression ring