Upon driver releasing the treadle in an air brake system, to where does the air get directed?
- Into the compressor
- Back into the reservoir
- Through the brake drums
- Into the atmosphere ✓
Answer: D. Into the atmosphere
Releasing the treadle directs the air into the atmosphere.
Why this is the answer
The handbook describes compressed air exhausting from air brake system components and lists the exhaust ports of brake valves among the places where it leaves the vehicle. When the treadle releases, the brake valve is no longer holding that air in the applied circuit, so the air is exhausted rather than sent back through the supply side. The handbook also warns that this exhaust travels at high speed and can carry moisture, oil, dirt and dust, which is why you should stay clear of the exhaust path.
Why the other answers are wrong
- A. Into the compressor — The compressor is the source that draws in air and pressurizes it for the system, not the place where released brake air is directed.
- B. Back into the reservoir — The reservoir or supply tank stores compressed air for use; the passages describe air being exhausted from brake valves, not returned to the reservoir when the treadle is released.
- C. Through the brake drums — Brake drums are part of the wheel brake assembly, and the passages do not say that air is routed through them when the brake valve is released.
Remember it
Keep clear of brake valve exhaust ports; released air leaves the vehicle there at high speed.