🔍 Key Concepts

• Study how the component labeled III is connected to the cam/rocker gear in the illustration. • Recall how a typical direct-acting air starting valve is opened and how it returns to the closed position. • Think about what happens to the air starting valve when starting air is no longer admitted to the cylinder.

💭 Think About

• Look closely: does the cam (or push rod) act directly on the air starting valve, or on a small pilot/control valve that then uses air pressure to move the main valve? • When the engine is running normally on fuel, should high‑pressure starting air be entering the cylinder at every revolution, or only during starting? What does that imply about the motion of valve III? • If starting air pressure is removed from the system, what force (spring, air, or cam) will determine whether valve III is open or closed?

✅ Before You Answer

• Verify whether label III is attached to a mechanical linkage (rod/lever) or to the air passage itself. • Confirm whether the main air starting valve in the illustration is air-operated and spring‑closed, or purely cam/mechanical operated. • Check which statement correctly describes the valve’s position and operation only during the starting period versus during normal running.