🔍 Key Concepts

• Cam profile shape in a two-stroke diesel and how the follower is accelerated and decelerated • Where on a rotating cam the greatest tendency to separate (leave the surface) occurs: during rapid acceleration vs. deceleration • Relationship between spring force, inertia of the valve train, and cam speed

💭 Think About

• On which part of the cam motion is the follower being pushed hardest away from the cam by inertia rather than being pressed into it? • Does a sudden increase in lift (rising flank) or a sudden decrease in lift (falling flank) create more tendency for the follower to lose contact at high RPM? • Think about what happens if the valve gear is moving upward quickly and the cam surface suddenly “drops away” versus when it is just starting to move up.

✅ Before You Answer

• Identify whether acceleration or deceleration of the follower increases the risk of separation from the cam • Determine which event (intake or exhaust, opening or closing) usually involves the steepest cam flank and highest speed of movement • Consider how valve spring force vs. inertia affects contact when the cam profile changes direction quickly