🔍 Key Concepts

• Manufacturer’s recommended limits for lubricating oil temperature rise across reduction gears and bearings • Why excessive oil temperature can damage gear teeth and bearing surfaces • Typical engineering practice limits for temperature rise in closed-loop lube oil systems

💭 Think About

• Think about what happens to lubricating oil properties (viscosity, film strength) as the temperature increases too much. • Consider which choice seems most consistent with protecting expensive reduction gears and bearings during continuous operation. • Ask yourself: would engineers design for a small, moderate, or very large temperature rise to ensure both efficiency and safety?

✅ Before You Answer

• Check which option represents a conservative, continuous-service limit rather than a short-term or emergency limit. • Make sure the value you pick seems reasonable for maintaining oil viscosity and preventing metal-to-metal contact. • Verify that the chosen rise is something a shipboard lube oil cooling system could realistically maintain under normal load.