🔍 Key Concepts

• Purpose and function of a jacking gear on a turbine-driven vessel • What happens mechanically if the main turbine tries to turn while the jacking gear is still engaged • Relative strength and design of the jacking gear components versus the main propulsion system

💭 Think About

• Think about the torque produced by main steam on the propulsion turbine compared to the small motor driving the jacking gear. Which components are most vulnerable if both are trying to turn the shaft? • Consider which option describes a sudden, high-stress mechanical failure rather than a gradual operating condition. • Ask yourself: is the jacking gear designed to transmit full turbine torque, or just to slowly turn the shaft for maintenance and warming?

✅ Before You Answer

• Identify that jacking gear is a low-speed, low-torque device used for turning the shaft slowly during warm-up or maintenance. • Decide which listed problem would be immediate and serious if full steam torque was applied with jacking gear still engaged. • Eliminate any choices that describe conditions likely to occur even under normal, correctly operated warm-up procedures.