🔍 Key Concepts

• Purpose of a jacking gear on a turbine-driven propulsion plant • Relationship between jacking gear and reduction gears • When turbines are stopped, what must be done to prevent rotor damage or gear damage

💭 Think About

• Ask yourself: Is a jacking gear designed to move the ship through the water, or to slowly turn/position internal machinery? • Think about why engineers might want the main shaft or reduction gear to rotate very slowly when the plant is secured or being inspected. • Which option sounds like a low‑speed, precise, maintenance/inspection function rather than an operating or maneuvering function?

✅ Before You Answer

• Identify which option clearly relates to slow turning for inspection or protection of gears/shafts. • Eliminate any choice that suggests normal propulsion or maneuvering capability. • Check which answer directly involves the reduction gear teeth rather than the turbine’s operating speed while underway.