Free Practice Questions for Vermont CDL Air Brakes
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7 Job WikiSample Vermont CDL Air Brakes Practice Questions
Try these sample questions to review concepts for the Vermont CDL Air Brakes exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 220+ question experience with AI tutoring.
1What three distinct braking systems are combined into an air brake system on a commercial motor vehicle?
2What is the primary function of the air compressor on an air-brake equipped commercial vehicle?
3How is the air compressor typically lubricated on most heavy commercial vehicles?
4Which air-brake component signals the compressor to begin and stop charging the reservoirs?
5What approximate governor cut-out pressure does the Vermont CDL Manual use for a typical air-brake system?
6At what pressure does the compressor governor allow the air compressor to resume pumping air (cut-in pressure)?
7Why must air storage tanks be drained regularly if they are not equipped with automatic drain valves?
8When should a driver drain reservoirs that have manual air-tank drain valves?
9Why might an air-brake system use an alcohol evaporator in freezing weather?
10What maintenance duty must a commercial driver perform on an alcohol evaporator during winter operating months?
About the Vermont CDL Air Brakes Exam
The Vermont CDL Air Brakes knowledge test is administered by the Vermont Department of Motor Vehicles (DMV) and covers Section 5 of the Vermont CDL Manual (VN-111). Passing it and completing skills testing in the appropriate air-brake vehicle are required to avoid the federal Restriction L (No Air Brakes) or Restriction Z (No Full Air Brake Equipped CMV). The test covers pneumatic components, dual air systems, foundation brakes, slack adjusters, low-pressure warnings, safety valves, in-cab inspection tests, leakage rates, brake lag, and mountain braking. Vermont DMV does not publish the official item count or time limit. Independent OpenExamPrep practice uses original four-option study questions and does not replace official DMV knowledge or skills testing.
Exam sponsor: Vermont Department of Motor Vehicles. The requirements and fees below concern the certification or admission exam, separate from our free practice resources.
Assessment
A knowledge examination administered at Vermont DMV offices covering Section 5 of the Vermont Commercial Driver License Manual (VN-111). Applicants must score at least 80% and complete skills testing in a full-air-brake commercial vehicle to operate full-air-brake CMVs without an L or Z restriction.
Time Limit
Not published by Vermont DMV
Passing Score
At least 80% correct under 49 CFR 383.135
Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.
Official sources
- Vermont DMV Commercial Driver License Information · Source checked 2026-10-04
- Vermont Commercial Driver License Manual (VN-111) · Source checked 2026-10-04
- Vermont DMV CDL Fees · Source checked 2026-10-04
- 49 CFR Part 383 (Commercial Driver's License Standards) · Source checked 2026-10-04
- 49 CFR § 393.51 (Warning Signals and Devices for Air Brakes) · Source checked 2026-10-04
Our practice resources: topics covered
We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.
Air Brake System Parts
Three brake systems (service, parking, emergency); compressor and governor (cut-in about 100 psi and cut-out about 125 psi); air storage tanks, manual and automatic drain valves, alcohol evaporators, safety relief valve (usually 150 psi), foot valve, foundation brakes (S-cam, wedge, disc), pressure gauges, low-air warning devices (before pressure falls below 55 psi, or the manufacturer-specified higher level), stop-light switch, and front-brake limiting valves.
Spring Brakes and Parking Controls
Mechanical coil spring brakes, automatic emergency application between 20 and 45 psi, yellow diamond parking-brake control knob, tractor protection valve, modulating valves, and dual parking control valves.
Dual Air Brake Systems
Primary (rear axle) and secondary (front axle) independent pneumatic circuits, shared compressor and reservoirs, dual pressure gauges, low-pressure warnings, and vehicle stopping capabilities if one circuit loses pressure.
Inspecting Air Brake Systems
Pre-trip inspection of hoses, lines, chambers, and slack adjusters (about 1 inch maximum hand movement at the pushrod connection); compressor drive belt; static leakage test (max 2 psi/min single, 3 psi/min combination); applied leakage test (max 3 psi/min single, 4 psi/min combination); low-air warning check (before pressure falls below 55 psi or the manufacturer-specified level); spring-brake pop-out check (20-45 psi or manufacturer specification); pressure buildup time (85-100 psi within 45 seconds); governor cut-in/cut-out verification; and parking/service brake holding tests.
Using Air Brakes and Stopping Techniques
Normal stopping, brake lag distance (approx. 0.4 to 0.5 seconds / 32 feet at 55 mph), total stopping distance (over 450 feet at 55 mph), controlled braking versus stab braking, anti-lock braking systems (ABS), downhill braking techniques (snub braking 5 mph below safe speed), brake fade from excessive heat, and proper parking brake usage.
Preparing for the Vermont CDL Air Brakes Exam
What You Need to Know
- Passing score: At least 80% correct under 49 CFR 383.135
- Assessment: A knowledge examination administered at Vermont DMV offices covering Section 5 of the Vermont Commercial Driver License Manual (VN-111). Applicants must score at least 80% and complete skills testing in a full-air-brake commercial vehicle to operate full-air-brake CMVs without an L or Z restriction.
- Time limit: Not published by Vermont DMV
- Exam / certification fees: $39 knowledge test fee; $18 CLP fee Official sources
Using Our Practice Resources
- Work through all 220 available questions
- Review every answer and explanation
- Track weak areas and revisit them
- Use our AI tutor for tough concepts
Vermont CDL Air Brakes: Suggested Study Strategy
Frequently Asked Questions
What is the passing score for the Vermont CDL Air Brakes test?
Under 49 CFR 383.135, applicants must score at least 80% to pass a CDL knowledge test. Vermont DMV publishes the Air Brakes test's Section 5 scope but does not publish its official item count or time limit.
What happens if I take my Vermont CDL skills test in a vehicle without air brakes?
Under 49 CFR 383.95 and Vermont DMV regulations, if you take your skills test in a vehicle that is not equipped with air brakes, your CDL will carry Restriction L (No Air Brakes), preventing you from legally operating any commercial vehicle equipped with an air brake system.
At what air pressure must the low air warning signal activate?
The Vermont CDL Manual requires the low-air warning to activate before pressure falls below 55 psi, or at the manufacturer-specified higher level. It notes that large-bus warning devices commonly activate at 80-85 psi.
What are the acceptable air leakage rates during an in-cab inspection?
For a single vehicle, the static leakage rate (brakes released) must not exceed 2 psi in one minute, and the applied leakage rate (brakes fully applied) must not exceed 3 psi in one minute. For combination vehicles, the limits are 3 psi in one minute static and 4 psi in one minute applied.
What is the proper technique for braking on steep mountain downgrades in Vermont?
Shift into a low gear before beginning the descent. Apply the brakes firmly enough to slow the vehicle to 5 mph below your safe speed (e.g., from 40 mph down to 35 mph), then completely release the brakes. Repeat this snub-braking technique whenever vehicle speed creeps back up to your safe speed to allow brake drums to cool.
Are these practice questions identical to the official Vermont DMV exam?
No. These are independent educational study questions based on Section 5 of the Vermont CDL Manual (VN-111) and federal safety regulations. They do not reproduce official exam questions.