🔍 Key Concepts

• Function of inflatable clutch glands in a marine reduction gear • How ahead/astern (or directional) control is achieved in a single‑engine, single‑shaft installation • Why a designer would need two separate clutches on one reduction gear

💭 Think About

• Look at where the two inflatable clutch glands are located in the illustration: do they act on the same gear or on different gears/shafts? What does that suggest about their purpose? • Ask yourself: in normal operation, would it make sense to have one clutch just sitting idle as a spare, or would both clutches have an operational role? • Think about how a fixed‑direction diesel engine can still drive the propeller in both ahead and astern directions. What must the reduction gear be able to do, and how might two clutches help with that?

✅ Before You Answer

• Verify whether the gear shown has two different driven paths from the input shaft to the output shaft (look for two different gear trains or directions). • Check if a two‑speed gear would normally need two inflatable glands on opposite sides of the same gear, or if it would more likely use a different arrangement (like multiple gear trains or planetary gearing). • Confirm whether a true spare clutch gland would be mounted in a way that it can be isolated and replaced, or whether the drawing shows both glands integrated into the normal operating mechanism.