🔍 Key Concepts

• Relationship between control air (CA), start air (SA), and the labeled opening (OP) and closing (CP) pilot air ports • Purpose of an air distributor mounted on the camshaft of a large slow-speed diesel engine • Difference between systems that control starting, governor oil pressure, reversing hydraulics, and intake/exhaust valve timing

💭 Think About

• Look at where the control air inlet (CA) goes and where the start air outlet (SA) is directed. What component of the engine would need timed bursts of start air? • Why would this device be driven by the camshaft and have markings for base circle (BC) and cam circle (CC)? What does that tell you about its timing role? • Which of the choices actually involves air as the working medium, and which involve oil or hydraulic fluid instead?

✅ Before You Answer

• Verify which ports are labeled with air-related abbreviations (CA, SA, EA, OP, CP) and which answer choice matches an air-distribution function. • Confirm that this unit is concerned with the starting sequence (opening and closing of something only during start) rather than continuous running functions like valve timing or governor lubrication. • Eliminate any choice that refers to lube oil or hydraulic pressure since the illustration clearly shows an all-air manifold and distributor.