🔍 Key Concepts

• Main blocking valve for control air shown at the lower left of the illustration • Relationship between the emergency fuel control lever (running without governor) and the pneumatic signal going to the control circuit • How moving the manual throttle away from the ‘zero’ position affects governor control and air supply

💭 Think About

• Look at how the linkage from the emergency fuel control lever connects mechanically to the symbol for the pneumatic valve. When that lever is moved, what happens to the flow of control air? • Ask yourself whether this valve is meant to pass normal steady control signals, stop them, or protect the system from unwanted or transient changes. • Consider what must happen to the governor’s influence when you want to run the engine manually in an emergency. How would a pneumatic valve help achieve that?

✅ Before You Answer

• Identify which part of the diagram is the pneumatic (air) valve and trace the line labeled ‘From control air supply (7 bar)’. • Decide whether the valve’s main job is to equalize input and output pressure, block/secure air to the control circuit, or filter out transient signals. • Confirm how the lever labeled ‘Fuel control lever for emergency running without governor’ interacts with the valve and what that implies about the governor’s authority.