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Securing a CDL without an air brake restriction is vital for expanded job opportunities in Missouri because most semi-trucks, tractor-trailers, and large buses rely on air brakes for safe navigation. Failure to pass the Missouri DOR CDL Air Brakes Knowledge Test results in your CDL including the restriction “L,” which will prevent you from operating commercial motor vehicles (CMVs) with air brakes. Failing the air brakes test in Missouri also results in a one-day waiting period and a retest fee should you decide to retake the test. Our Missouri DOR CDL Air Brakes Practice Tests help you pass your knowledge exam on the first attempt.
From the rolling hills, river valleys, and flat plains to the steep grades and winding roads of the Ozark Mountains, Missouri’s diverse terrain demands the mastery of air brakes for hauling heavy loads in these regions. Key transportation routes include I-70 (major east-west route from St. Louis to Kansas City), I-44 (passes through the Ozarks with steep grades), Route 60 (east-west corridor with hilly terrain), and I-55 (follows the Mississippi River). Given these challenges (and the opportunities they provide), the restriction “L” would severely limit your job prospects.
M.S., Chief Educational Researcher (ACES member)
Last verified for accuracy on
The Show Me State relies on drivers with the air brake qualification in key industries, including agriculture, manufacturing and freight (Boeing and Ford), and tourism (Branson and Lake of the Ozarks). Major companies requiring this qualification include Hogan Transportation (St. Louis), Prime Inc. (Springfield), and YRC Freight (Kansas City) in the logistics sector, as well as Jefferson Lines (Kansas City and St. Louis) and Metro Transit (St. Louis) in the charter bus and public transit industry. Missouri’s school districts also employ thousands of air brake-qualified drivers for their full-size school buses. The “L” restriction makes all these opportunities unattainable.
Our CDL Air Brakes Practice Tests cover all key information for the official DOR Air Brakes Knowledge Test. The information you learn will also be useful as you practice inspecting and operating CMVs to pass your skills test. Featuring multiple-choice questions that are based on the state’s CDL manual (Missouri CDL Handbook 2026), the written Air Brakes knowledge test requires a score of at least 80% to pass.
Our practice tests also provide real-time feedback on all responses. This scientifically proven approach helps you learn faster and ensures you pass the test.
Driver’s Ed is - nobody wants to set foot inside the DOR. That’s why millions of learners trust us for simple, visual, effective prep.
We are an officially recognized FMCSA Entry-Level Driver Training provider and a proud partner to over 2,500 libraries. We work with safety organizations like GHSA and the National Safety Council to help create safer roads for everyone.
Our trademarked system automatically saves questions you miss, creating personalized tests that target your weak spots until you’ve mastered the material.
Get smarter as you study. Our new AI-powered feedback provides detailed, question-level insights to help you understand the why behind each answer.
Go beyond the boring black-and-white manual. Our interactive handbook lets you read, listen with an MP3 audio version, or even chat with it to find the information you need, faster.
We build our practice questions from the current 2026 MO Driver Handbook and refine them using patterns recent test‑takers report.
Driver handbook • Knowledge‑test/permit overview • Fees & ID requirements • Office/appointment info
We mirror recurring themes (e.g., right‑of‑way traps, sign look‑alikes) and use similar distractors and wording styles.
We don’t collect or publish actual test items and we’re not affiliated with DOR.
