Is there generally a brief delay in air brake response when the brake pedal is pressed or released?
- This happens only in older air brake systems
- This is common in all hydraulic brake systems
- This never happens in well-maintained systems
- This is common in all air brake systems ✓
Answer: D. This is common in all air brake systems
Yes — a brief delay is common in all air brake systems when the pedal is pressed or released.
Why this is the answer
The handbook explains that air brakes work by moving compressed air from storage tanks through valves to the wheels. Even though the valves are designed to move the air quickly, there is a tiny lag between when you apply or release the pedal and when the brakes react. The passage states plainly that this short delay happens in every air brake system, which is why it is not limited to old, poorly maintained, or hydraulic setups.
Why the other answers are wrong
- A. This happens only in older air brake systems — Older systems are not the point, because the handbook says the short lag is present in every air brake system, not just aging ones.
- B. This is common in all hydraulic brake systems — Hydraulic brakes are a different design; the passage ties the lag to compressed air moving through an air brake system, not to hydraulic brakes.
- C. This never happens in well-maintained systems — Well-maintained systems still have the lag, since the handbook says it occurs in all air brake systems, not only neglected ones.
Remember it
Think “air has to travel”: expect a small lag both when you press and when you release.