OK CDL Air Brakes study guide
OK CDL Air Brakes · Work through your exam, one topic at a time.
The Oklahoma CDL Air Brakes knowledge test is the written exam a driver must pass to operate a commercial vehicle equipped with air brakes. It applies to Class A and Class B applicants whose vehicles use air brakes, and to drivers who already hold a CDL but carry an air brake restriction (typically restriction L) and want it removed. The OK CDL Air Brakes study guide has 7 sections and about 2,502 words.
01Air Brake System Components and Fundamentals
This domain tests how air is produced, stored, controlled, and turned into braking force. Expect questions on the compressor, governor, reservoirs, valves, brake chambers, slack adjusters, and foundation brakes, plus the pressure ranges that matter in the cab.
324 words, about 2 min02Dual Air Brake System and Safety Devices
This domain tests the split system that lets a vehicle stop after one circuit fails. You need to know primary and secondary circuits, check valves, low-pressure warning, spring brakes, tractor protection, and anti-compounding.
347 words, about 2 min03Inspecting and Using Air Brakes (Pre-Trip and In-Cab Checks)
This domain tests the air brake portion of the pre-trip inspection and the in-cab tests an examiner will watch. You must know the sequence, the limits, and what a failure looks like.
349 words, about 2 min04Air Brake System Malfunctions and Warning Signals
This domain tests what the gauges, lights, buzzers, and vehicle behavior tell you, and what to do before a small fault becomes a brake failure. Questions often use a pressure drop, a warning that stays on, or a compressor that will not keep up.
362 words, about 2 min05Normal Driving with Air Brakes (Stopping, Downgrades, Brake Fade)
This domain tests smooth, controlled use of air brakes: stopping distance, brake lag, downgrade technique, and preventing fade. The exam expects you to choose a gear and a speed before the grade, not to fix a hot brake halfway down.
377 words, about 2 min06Emergency Braking and Brake Failure Response
This domain tests what to do when service brakes fail, pressure drops, or a stop is unavoidable. The exam rewards controlled, progressive actions and penalizes panic moves that lock wheels or cause a jackknife.
360 words, about 2 min07Oklahoma and Federal Air Brake Rules, Restrictions, and Endorsements
This domain tests the legal side: CDL classification, the air brake restriction, Oklahoma adoption of federal CMV standards, and the difference between an endorsement and a restriction. The exam often asks what a driver may legally drive after testing in a vehicle without air brakes.
383 words, about 2 min