🔍 Key Concepts

• Valve spring dynamics in a high‑speed diesel engine • The meaning of spring surge and how it affects valve motion • How inertia of moving valve gear parts can cause separation from the cam profile

💭 Think About

• Which option directly relates to the behavior of the valve spring itself, rather than wear or adjustment issues? • What happens if the spring cannot follow the cam accurately at certain engine speeds—does the valve stay firmly on the cam, or does it momentarily lose contact and "bounce"? • Consider which condition would most likely cause a cyclic oscillation in the spring, leading to loss of control of the valve motion.

✅ Before You Answer

• Identify which choice describes a dynamic spring effect (not just a static condition like tightness or wear). • Ask: under which option could the spring start oscillating at its natural frequency, causing the valve to lift and close irregularly? • Eliminate options that are mainly about long-term wear or simple over‑tightening, rather than high‑speed dynamic motion of the valve train.