🔍 Key Concepts

• Cam lobe opening flank vs closing flank and what their steepness means for valve motion • How abrupt vs gradual changes in cam radius affect valve speed and potential for bounce • The direction of cam rotation shown by the arrow and which side of the lobe is used for valve closing (reseating)

💭 Think About

• Look at cam B and trace the rotation arrow. As the follower rides up and then back down, on which side does the valve close and reseat? Is that side steep or gently curved? • Compare the shape of cam B’s closing side to a symmetrical cam in figure A. Does cam B make the valve return to its seat more suddenly or more slowly than a symmetric profile would? • Think about valve bounce: would a very sudden stop at the seat make bounce more likely, or less likely? How does that relate to the answer choices?

✅ Before You Answer

• Identify exactly which part of cam B corresponds to valve closing (reseating) by following the rotation arrow. • Decide whether the closing flank in B is steeper or more gradual than the opening flank and than a normal symmetric cam. • Match that closing behavior to the choice that best describes how the valve returns to the seat (abrupt vs gradual, and effect on bounce).