You are checking a truck whose air compressor has its own oil supply. Which extra check belongs in the pre-trip inspection?
Correct answer: Check that compressor's oil level.
A separately lubricated compressor needs its own oil-level check. Engine lubrication does not automatically cover every compressor design.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.1, physical PDF page 92, printed page 5-1. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
During a stationary check, reservoir pressure falls to the manufacturer's cut-in setting. What should a functioning governor allow?
Correct answer: The compressor to resume building reservoir pressure.
Cut-in is the point at which the compressor resumes charging the air reservoirs. Check the actual cut-in and cutoff settings specified for that vehicle.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.2, physical PDF page 92, printed page 5-1. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
Water has accumulated in an air reservoir before a freezing night. What brake-system risk does this create?
Correct answer: Ice can obstruct components and interfere with braking.
Moisture carried in compressed air can collect in the tanks and freeze. Removing contamination helps prevent brake-system failures in cold conditions.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.4, physical PDF page 92, printed page 5-1. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A truck has manual tank drains and no automatic drainage. When should the driver complete the regular draining task described in the manual?
Correct answer: At the end of each driving day.
The manual's daily draining instruction applies to tanks that require manual drainage. Water and oil can accumulate in warm weather too.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.4, physical PDF page 92, printed page 5-1. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
On a spring-brake-equipped truck, what normally keeps the powerful parking-brake springs from applying while driving?
Correct answer: Sufficient air pressure holding the springs back.
Air pressure holds the spring brakes released. Loss or release of that air allows the mechanical springs to apply the brakes.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.14, physical PDF page 94, printed page 5-3. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
The wheel brakes on a spring-brake truck are out of adjustment. Which braking capability can be affected?
Correct answer: Both normal braking and spring-brake holding power.
Adequate air pressure alone cannot correct a mechanical adjustment defect. The same wheel-brake condition can undermine service and spring-brake effectiveness.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.14, physical PDF page 94, printed page 5-3. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A truck lacks a reliable anti-compounding feature. Why should its driver avoid a hard foot-brake application while the spring brakes are applied?
Correct answer: The combined forces can damage the brake mechanism.
Service pressure and spring force can act together. Not every system prevents this compounding, so the driver must use the controls as specified for the vehicle.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.15, physical PDF page 94, printed page 5-3. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A bus has a separate emergency reservoir that can briefly release applied spring brakes after main-air loss. What should the driver remember?
Correct answer: That reserve permits only a limited number of releases.
A reserve air supply is finite and must be managed carefully during an emergency move. It is not a repair or an unlimited replacement for the main air system.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.15, physical PDF page 95, printed page 5-4. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
During a walk-around, you find oil-soaked brake lining and a hose worn by rubbing. What is the appropriate assessment?
Correct answer: These are brake defects that must be addressed.
Reservoir pressure cannot prove that friction material and hoses are sound. Contaminated lining and damaged air hoses require attention before relying on the brakes.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.3.2, physical PDF page 97, printed page 5-6. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
While using controlled braking in a vehicle without ABS, the wheels lock. What is the correction described for that method?
Correct answer: Release the brakes, then reapply as soon as control permits.
Controlled braking aims to avoid wheel lock while preserving direction. A lockup calls for release and timely reapplication; this is not an instruction to pump functioning ABS.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.3, physical PDF page 99, printed page 5-8. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A stopping-distance estimate includes perception, reaction and wheel-braking distance. Which additional allowance is important for an air-braked vehicle?
Correct answer: Distance traveled while air pressure reaches and operates the brakes.
Air-brake response includes a delay between pedal application and braking action. That travel distance adds to the other parts of the stopping-distance estimate.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.4, physical PDF page 99, printed page 5-8. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A driver proposes reducing following space because the truck has ABS. Which explanation best corrects that decision?
Correct answer: ABS helps control wheel lock but does not guarantee a shorter stop.
The main ABS benefit is wheel-lock control during braking. It does not eliminate reaction time, traction limits or the need for adequate following space.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.1.16, physical PDF page 95, printed page 5-4. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
Several wheel brakes are out of adjustment while the others work correctly. Why does this also threaten the working brakes on a descent?
Correct answer: The working brakes may carry extra load, overheat and fade.
If some brakes do less work, the others must absorb more of the vehicle's braking demand. This can overheat them and reduce overall control.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.5, physical PDF page 100, printed page 5-9. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
Before a long, steep downgrade, how should the driver plan to control an air-braked truck's speed?
Correct answer: Select an appropriate low gear and use service braking as a supplement.
The engine's braking effect in a suitable gear helps control the descent. The service brakes supplement it; they should not carry the entire speed-control task.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.6, physical PDF page 100, printed page 5-9. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A driver has selected an appropriate low gear and a safe downhill speed of 35 mph. In the manual's described braking cycle, about when is the brake application released?
Correct answer: After slowing to about 30 mph.
The described cycle reduces speed by about 5 mph below the selected safe speed before release. This example is a technique illustration, not a universal safe speed for a hill.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.6, physical PDF page 100, printed page 5-9. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
At a safe, level stopping place, the brakes are very hot after a descent. What precaution does the manual describe before using the parking brakes?
Correct answer: Secure the vehicle with wheel chocks and let the brakes cool.
The manual warns about applying parking brakes to very hot brakes. Its stated alternative is wheel chocks on a level surface while cooling, not leaving the vehicle free to roll.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.4.8, physical PDF page 100, printed page 5-9. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A safely secured tractor-trailer loses 5 psi during the one-minute held-foot-brake leak check, with the engine off. How does this compare with the manual's applied-check limit?
Correct answer: It exceeds the 4-psi limit for that combination.
Section 5.3.3 treats more than 4 psi per minute as excessive for this combination-vehicle applied check. A 5-psi loss requires finding and correcting the leak before driving.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.3.3, Test Air Leakage Rate: applied combination, physical PDF page 98, printed page 5-7. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
In section 5.3.3's dual-system low-pressure warning check, the lower-pressure reservoir falls through 60 psi without any warning. Which result was expected?
Correct answer: The warning should activate before the tank pressure falls below 60 psi.
This question uses the manual's dual-system inspection example, not another state's exam rubric. It calls for a warning before the lowest tank falls below 60 psi. A missing warning requires correction; do not wait for spring-brake application while driving.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.3.3, Test Low Pressure Warning Signal, physical PDF page 98, printed page 5-7. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
For a conventional pop-out system in section 5.3.3's spring-brake check, which pressure range does the manual give while directing the driver to the manufacturer's specification?
Correct answer: 20–45 psi, with the actual vehicle specification identified.
The manual gives 20–45 psi for this conventional automatic-application check and identifies the manufacturer's specification as the reference. This is distinct from the low-air warning and governor cutoff; it is not a universal rule for every control design.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.3.3, Check That Spring Brakes Come On Automatically, physical PDF page 98, printed page 5-7. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
A driver is preparing a supervised stationary air-brake check that requires releasing the parking brakes. What safeguard should be established before releasing them?
Correct answer: Prevent vehicle movement with suitable wheel chocks on a safe, level surface.
An air check must not allow the vehicle to roll when parking brakes are released or pressure changes. Secure the vehicle with wheel chocks and follow the applicable equipment and instructor procedures before testing.
Source: Louisiana OMV-linked Commercial Driver License Manual, July 2017 cover version; section 5.3.2 (level-ground wheel restraint) and 5.3.3 (continued on physical page 98), physical PDF page 97, printed page 5-6. Equipment knowledge, not a claim about current Louisiana test scoring; actual vehicle instructions and supervised training remain necessary. ↗
