🔍 Key Concepts

• Air starting systems on medium and slow-speed diesel engines • How valve timing is usually achieved in reciprocating engines • Difference between an air supply component and a timing/control component

💭 Think About

• Which part of the system actually decides when high-pressure air reaches each cylinder during starting? • Look at each option and ask: is this primarily about providing air, distributing fluid, or mechanically synchronizing with the crankshaft? • In a conventional diesel, what keeps the opening of inlet/exhaust/fuel events in step with crankshaft position? Does the same principle apply to air start valves?

✅ Before You Answer

• Identify which option is mechanically linked to crankshaft position so timing stays correct as the engine turns • Separate components that supply or distribute air/fluid from those that control event timing • Ask whether the correct device would still keep accurate timing if engine speed changes — what design makes that possible?