đ Key Concepts
⢠Four-stroke diesel cycle events at the cylinder (intake, compression, power, exhaust)
⢠Parts actually located in the cylinder head of a large, direct-reversible, direct air-start engine
⢠Which head-mounted components need precise camshaft timing (as opposed to safety/relief or indicator devices)
đ Think About
⢠List every device that is physically in the cylinder head on a typical direct admission air-start marine diesel, then cross out anything that is not âtimedâ.
⢠For each remaining device, ask: does its opening/closing depend on crank angle and camshaft control, or is it purely pressure-operated/safety-related?
⢠Connect each stroke of the 4-stroke cycle with what must happen in the head for that stroke to occur correctly, including starting and normal running.
â
Before You Answer
⢠Be sure you only count events controlled by valve or fuel timing (camshaft-governed), not safety valves or indicator cocks.
⢠Confirm that youâre thinking only about events in the cylinder head, not in the fuel pump, starting air manifold, or governor elsewhere.
⢠Make sure you include the extra timed function needed for direct admission air starting, in addition to normal 4-stroke operation.