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Texas CDL practice test

Getting a commercial driver's licence in Texas starts with the CDL knowledge tests. The content is federal: every state, Texas included, writes its tests from the FMCSA CDL manual, so the general knowledge test has 50 questions, the endorsement tests have 20 to 30, and the passing score is 80% on each. The Texas driver licensing agency administers the test; the rules behind it are published by the FMCSA. Try the free Texas CDL practice questions below, then pick a full test.

Free Texas CDL practice questions

Five questions from the general knowledge, air brakes and combination vehicles banks, the three tests most Texas Class A applicants take first. Show the answer to read the explanation.

  1. When backing a trailer, to make the trailer go left you should:

    • Turn the top of the steering wheel to the left
    • Turn the top of the steering wheel to the right
    • Use the trailer hand valve
    • Keep the wheel straight and use the mirrors
    Show answer
    Answer: B. Turn the top of the steering wheel to the right

    The trailer goes the opposite way from the top of the steering wheel. Turn right to push the trailer left, then straighten and follow it. Back toward the driver's side when you can, use pull-ups to fix your angle, and get out and look.

    Source: FMCSA CDL Manual, Section 6.1.5 (Backing with a Trailer)

  2. On the air lines between tractor and trailer, the emergency (supply) line and its glad hand are colored:

    • Blue
    • Red
    • Green
    • Yellow
    Show answer
    Answer: B. Red

    Red is the emergency or supply line, which charges the trailer tanks and controls the trailer spring brakes. Blue is the service line, which applies the trailer brakes with the pedal. Metal tags on the lines help too.

    Source: FMCSA CDL Manual, Section 6.2 (Trailer Air Lines and Hose Couplers)

  3. The trailer hand valve (trolley valve) should be used:

    • To slow the rig on a downgrade
    • As a parking brake
    • Only to test the trailer brakes
    • To prevent jackknifing on a curve
    Show answer
    Answer: C. Only to test the trailer brakes

    Applying only the trailer brakes while moving can lock the trailer wheels and start a skid, and the hand valve cannot park the rig because air can leak off. Use it to test the trailer brakes and nothing else.

    Source: FMCSA CDL Manual, Section 6.2.1 (Trailer Hand Valve)

  4. The tractor protection valve:

    • Keeps the trailer from rolling when parked
    • Keeps air in the tractor if the trailer breaks away or develops a bad leak
    • Limits the front brake pressure
    • Holds the kingpin in the fifth wheel
    Show answer
    Answer: B. Keeps air in the tractor if the trailer breaks away or develops a bad leak

    If the trailer air line breaks, the valve closes (around 20 to 45 psi) so the tractor keeps its own air and brakes. Closing it also lets the air out of the trailer emergency line, which puts on the trailer spring brakes.

    Source: FMCSA CDL Manual, Section 6.2.2 (Tractor Protection Valve)

  5. Pulling out the red eight-sided trailer air supply knob:

    • Releases the trailer brakes
    • Shuts off air to the trailer and applies the trailer emergency (spring) brakes
    • Applies the tractor parking brake only
    • Tests the low air warning
    Show answer
    Answer: B. Shuts off air to the trailer and applies the trailer emergency (spring) brakes

    The red knob controls the air supply to the trailer. Push it in to send air to the trailer; pull it out to cut the air off and set the trailer emergency brakes. It pops out on its own if pressure drops into the 20 to 45 psi range.

    Source: FMCSA CDL Manual, Section 6.2.3 (Trailer Air Supply Control)

Every CDL test for Texas drivers

Each page has ten free sample questions, the real question count, the 80% pass mark and what the test covers.

How the Texas CDL knowledge test works

You take the general knowledge test first; it is required for every CDL class. Class A drivers add the combination vehicles test. Almost everyone takes the air brakes test, because skipping it puts an air brake restriction on the licence. Endorsements (hazmat, tanker, doubles/triples, passenger, school bus) each have their own knowledge test. Pass the tests and you hold a commercial learner's permit; the skills test in a truck comes later.

Fees, appointment rules and test centre locations are set by Texas and change over time, so check the state driver licensing agency before you go. What does not change is the content, and that is what PassRig drills.

Texas CDL test questions

How many questions are on the Texas CDL test?

The Texas CDL general knowledge test follows the federal model: 50 questions, 40 correct to pass. Endorsement tests are shorter: air brakes 25, hazmat 30, and combination vehicles, tanker, doubles/triples, passenger and school bus 20 each.

What is the passing score on the Texas CDL permit test?

80% on every knowledge test, the same pass mark used across the United States.

Where do I take the CDL knowledge test in Texas?

At the Texas state driver licensing agency (the DMV, DOT or equivalent). Check its website for locations, appointments and current fees; the test content itself comes from the FMCSA CDL manual.

Does PassRig have Texas CDL practice questions?

Yes. Pick Texas in the app and you get practice sets and mock exams built from the knowledge test content your state uses, with the real counts and the 80% line.

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