149. Your truck has a dual air system and one of the systems loses its pressure. What will happen?
Detailed Explanation
The correct answer is "Either the front or back brake will not be fully operational.". This question tests general CDL knowledge and the safest action expected of a commercial driver. For a differently worded version of this question, identify the hazard first and then choose the answer that preserves control, visibility, or legal compliance.
Correct Answer: Either the front or back brake will not be fully operational.
Why This Matters on the CDL Test
This question belongs in your brake safety review. Pay close attention to pressure limits, inspection steps, stopping distance, and warning signs because brake-system mistakes are a common reason CDL applicants miss endorsement questions.
How to Remember It
Say the rule in your own words, then explain why the wrong answers are unsafe or incomplete. That habit makes similar General Knowledge questions easier when the exam changes the wording.
Answer Review
Choose "Either the front or back brake will not be fully operational." because this answer matches the safe CDL action for brake system safety. On the knowledge test, the safest answer is usually the one that protects space, control, visibility, legal compliance, or inspection accuracy before the vehicle is put at risk.
Why the other answers are weaker
- The manual slack adjusters of the S-cam brakes will not be set properly."The manual slack adjusters of the S-cam brakes will not be set properly." does not best answer this brake system safety question. When you see a similar option on the CDL permit test, compare it against the exact safety rule and choose the answer that prevents the most immediate risk.
- Brake drums will not be fully pressurized."Brake drums will not be fully pressurized." does not best answer this brake system safety question. When you see a similar option on the CDL permit test, compare it against the exact safety rule and choose the answer that prevents the most immediate risk.
Test-Day Checklist
- Read the question once for the topic, then read it again for the exact CDL action being tested in General Knowledge.
- Eliminate answers that sound convenient but skip an inspection, warning sign, or safety step.
- Say the correct rule out loud before moving on so you can recognize it when the exam changes the wording.
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Start Practice TestRelated Questions
11. You are driving a new truck with a manual transmission. What gear will you probably have to use to take a long, steep downhill grade?
130. You are checking your brakes and suspension system for a pre-trip inspection. Which of these statements is true?
142. The biggest problem with a broken exhaust system is that it may let poison fumes into the vehicle's cab.
152. The oil pressure gauge should come up to normal within how long after starting the engine?
184. You should let air out of hot tires so the pressure goes back to normal.
Keep Studying General Knowledge
Question pages help you review one rule at a time. To build test-day speed, move back into the full General Knowledge practice test and answer a mixed set without looking at the explanation first.
State CDL Practice Paths
After you understand this answer, use a state practice path to connect the federal CDL rule with the DMV test pages drivers search for most.