Can the foot control valve maintain the application pressure that you've selected, even if there is a small leak downstream from the foot valve?

1. Yes ✓
2. Yes, but only if the leak is not in the primary system
3. Yes, but only if the leak is in a brake chamber
4. No, any leak will cause a severe drop in application pressure

Answer: A. Yes

Yes. The foot control valve can maintain the application pressure you selected even when there is a small leak downstream from the foot valve.

Why this is the answer

The handbook describes the foot valve as a pressure regulator controlled by the pedal. If you hold the treadle in one position, the pressure sent to the brakes stays constant. It also says a special feature of this valve is that it keeps the pressure you chose when small leaks occur downstream. The valve briefly opens to replace lost air and then closes on its own, so you just keep the treadle position.

Why the other answers are wrong

• B. Yes, but only if the leak is not in the primary system — The passage does not limit this holding ability to leaks outside the primary system; it describes small leaks downstream from the foot valve generally.
• C. Yes, but only if the leak is in a brake chamber — It does not say the valve can hold pressure only when the leak is in a brake chamber; the feature is described for small downstream leaks.
• D. No, any leak will cause a severe drop in application pressure — This contradicts the passage, which says the valve can replenish lost air automatically when the leak is small, so a small leak does not force a severe drop.

Remember it

Think of the treadle as a pressure setting: hold it steady and the valve tops up small losses by itself.