OR CDL Air Brakes

It is a multiple-choice knowledge test taken on a computer at an Oregon DMV office. You select one answer per question from the choices shown. Confirm current scheduling and testing procedures on the Oregon DMV website, since office practices and appointment requirements change.

The Oregon DMV publishes the current question count and passing score, and those figures are not repeated here because they can change. Check the official Oregon DMV CDL pages or your local office before you test so you know exactly what to expect.

The Oregon DMV sets the current time allowance, so verify it with the agency rather than relying on secondhand reports. Most candidates finish knowledge tests well within the allotted window, but read each question fully; air brake questions often hinge on one qualifying word such as 'first' or 'immediately.'

It is moderately difficult for candidates who only skim the manual. The concepts are simple, but the test rewards precise recall of sequences: inspection order, leakage check steps, and what to do when the low pressure warning sounds. Candidates who can explain why each step exists usually pass comfortably.

Mixing up the three system checks. Candidates confuse the static leakage test with the applied leakage test, forget that the engine must be off and the system fully charged, or misstate what the spring brake test proves. Learn each check as a numbered procedure with a purpose, not as a list of facts.

Start with components and how air flows through the system, because everything else depends on that. Then study the dual-circuit system and safety features, followed by the pre-trip inspection, the three system checks, normal driving technique on grades, and finally emergency procedures. Review the checks last so they stay fresh.

Oregon DMV policy governs retesting, including any waiting period or additional fee. Because those rules are set by the agency and can be revised, confirm the current retake policy directly with the Oregon DMV rather than assuming you can retest the same day.

No. The knowledge test removes the air brakes restriction on your CDL, but you must also pass the vehicle inspection and skills tests in an air-brake-equipped vehicle. The written test proves you understand the system; the skills test proves you can inspect and operate it.

Do both. The manual gives specific allowable pressure loss for the static and applied tests, and those numbers are testable. But understanding why a leak rate matters, and what a failed check means for the vehicle, helps you answer scenario questions and prepares you for the real pre-trip inspection.

Expect to present identification and any required application materials, then take the knowledge test at a computer station. Confirm acceptable documents and appointment needs on the Oregon DMV site beforehand, since requirements vary by transaction and incomplete paperwork is a common reason candidates are turned away.