🔍 Key Concepts

• Reduction gear basic purpose in a marine engine room • Relationship between engine RPM and propeller RPM • Difference between changing speed/torque vs. changing type of motion

💭 Think About

• Think about how fast a diesel engine normally turns compared to how fast a ship’s propeller should turn efficiently. • Ask yourself: does a reduction gear usually make things go faster, slower, or just change the kind of motion? • Consider whether typical ships use one engine with one shaft, or if reduction gears are mainly used to split power to many shafts.

✅ Before You Answer

• Verify which choice deals with changing speed and torque rather than changing the kind of motion. • Eliminate any option that talks about converting rotary motion to linear motion, since gears are normally between rotating parts. • Check which option correctly reflects that reduction gears usually take a high-speed engine input and produce a lower-speed, higher-torque output.