🔍 Key Concepts

• air-bladder (pneumatic) clutches and how inflation changes their shape • relationship between internal air pressure and the contact area between clutch and drum • what must physically happen inside the clutch before the driven part can turn with the engine

💭 Think About

• Picture the bladder before and after air is added: does it move inward, outward, or away from the drum? • For torque to be transmitted, what needs to happen between the clutch gland and the drum surfaces: more contact or less contact? • If the inside diameter of a circular bladder changes, in which direction must the rubber move to grip something on its outside?

✅ Before You Answer

• Be clear which diameter we are talking about: inside diameter of the gland, not the outside • Think about how a balloon around a tube behaves when inflated—does its inner opening get larger or smaller? • Confirm which option directly leads to greater frictional engagement between the clutch and the drum.