🔍 Key Concepts

• Common types of gears used in marine reduction gearboxes • How thrust loads and noise/vibration are handled in propulsion systems • Differences between spur, helical, double helical, and bevel gears

💭 Think About

• Which gear type is best for smooth, quiet power transmission at high load and continuous duty? • Which gear tooth arrangement helps cancel out axial (side) thrust in the gearbox? • Which gear type is typically used for changing shaft direction versus staying on the same shaft centerline?

✅ Before You Answer

• Identify which of the listed gear types is most commonly associated with main propulsion reduction gears in large marine engines • Check which gear types produce axial thrust and which designs can balance or eliminate it • Eliminate any gear types that are primarily used for changing shaft angle rather than for in-line reduction