🔍 Key Concepts

• Operation of a synchronous self‑shifting (SSS) clutch and why it is called “synchronous” and “self‑shifting”. • Difference between mechanical clutches and air-operated or hydraulically-operated clutches in marine propulsion gears. • Relationship between input shaft speed and output shaft speed needed for torque to be transmitted without shock loading.

💭 Think About

• Look closely at the illustration: do you see any obvious air chambers, air hoses, or inflation bladders that would be needed for an air clutch? What does that suggest about how this clutch is actuated? • Why would a synchronous clutch care about the relative speeds of the input and output shafts? What happens inside the clutch if one is significantly faster or slower than the other? • For smooth engagement and to avoid gear damage, should the driving member be trying to take hold when it is much faster, much slower, or very close in speed to the driven member?

✅ Before You Answer

• Verify whether an SSS clutch is normally purely mechanical or requires external air pressure for engagement. • Check which options describe a condition where input and output speeds are closely matched, allowing dogs or teeth to mesh without shock. • Eliminate any choices that would obviously cause severe shock or reverse loading on the gear train when the clutch tries to engage.