🔍 Key Concepts

• Flexible couplings purpose in a propulsion shaft line • Difference between torsional vibration control and torque transmission with misalignment • How gear-type construction affects load sharing and alignment limits

💭 Think About

• Ask yourself: What is the main design job of a gear-type flexible coupling in a main propulsion shaft—absorbing vibration, allowing slip, or transmitting torque despite minor misalignment? • Think about which option best matches a precision-machined gear mesh: is it intended to slip, to flex like rubber, or to carry high loads accurately? • Consider how much misalignment any precision gear teeth can really tolerate—large angular offsets or limited misalignment?

✅ Before You Answer

• Verify which answer mentions torque transmission rather than slip or thrust control. • Check which option talks about limited or minimal misalignment, which matches precision-built gear teeth. • Eliminate any choice that suggests intentional slip in the coupling, since main shaft couplings normally aim for no slip in power transmission.