Practice question

For the Washington CDL Air Brakes knowledge test, in which order should you typically drain the air storage tanks?

Any order is fine
Drain each tank fully, opening the drain valve until no more air, oil, or water comes out — most drivers start with the wet tank
Only drain the secondary tank
Drain them only after parking on a hill

Answer: B — Drain each tank fully, opening the drain valve until no more air, oil, or water comes out — most drivers start with the wet tank

The correct answer is shown above. Try the full quiz for additional practice.