What component prevents a complete loss of hydraulic system fluid if a brake line fails or leaks?

• A. Pressure relief valve
• B. Check valve
• C. Lockout Debooster valve
• D. Bleed valve

Answer: (C)

In a brake hydraulic system, preventing total fluid loss when a line ruptures relies on isolating the failed path. The lockout debooster valve is designed to do just that: when a dangerous pressure drop or rupture is detected, it locks out the affected circuit and prevents further hydraulic fluid from leaving through that line, preserving fluid in the rest of the system. This isolation keeps enough pressure available in the remaining circuits to provide at least partial braking rather than a complete loss of hydraulics. By contrast, a pressure relief valve just vents excess pressure, a check valve stops backflow but doesn’t isolate a leaking line, and a bleed valve is used only to remove air from the system.