🔍 Key Concepts

• Valve actuation methods used on large, low-speed, two-stroke marine diesel engines • How modern engines reduce mechanical parts between the camshaft and the exhaust valve • Differences between mechanical, pneumatic (air), and hydraulic valve actuation systems

💭 Think About

• Think about which systems are commonly used today to operate exhaust valves on very large, slow-speed main propulsion engines, not small or medium-speed engines. • Ask yourself: does the camshaft normally open the exhaust valve directly, or through some intermediate system on modern designs? • Consider which method allows variable timing and high force at the valve with fewer heavy moving parts at the cylinder cover.

✅ Before You Answer

• Verify which method is most associated with modern electronically controlled low-speed diesels (e.g., common rail / electronic camless concepts). • Check whether compressed air alone is typically strong and precise enough to repeatedly open large exhaust valves at high firing pressures. • Consider whether having long mechanical push rods from the camshaft to each exhaust valve is still common practice on the newest large low-speed engines, or if something has largely replaced them.