Alabama General Knowledge CDL Practice Test — Questions and Answers

Question 1: WHAT KIND OF FIRE IS A B:C EXTINGUISHER GOOD FOR?

Electrical, fuel (Correct answer)
Meat, cheese
Wood, paper, cloth
Metal, rubber

Correct answer: Electrical, fuel

A B:C fire extinguisher is specifically designed and rated for Class B and Class C fires. Class B fires involve flammable liquids like gasoline, oil, and grease (fuel), while Class C fires involve energized electrical equipment (electrical). This type of extinguisher uses agents that interrupt the chemical reaction of these fires without conducting electricity, making it safe and effective for these specific hazards.

Question 2: WHAT IS "HYDROPLANING"?

Tires lose contact with road and have no traction (Correct answer)
Turning steering wheel but vehicle doesn't turn
Braking but vehicle doesn't stop
Form of surfing

Correct answer: Tires lose contact with road and have no traction

Hydroplaning occurs when a vehicle's tires lose contact with the road surface due to a layer of water between the tires and the road. This loss of contact results in a complete loss of traction, making it impossible to steer, brake, or accelerate effectively. It's a dangerous condition that can lead to a loss of control, especially at higher speeds or in heavy rain.

Question 3: IF A TIRE BLOWS OUT, YOU SHOULD PUT THE BRAKES ON HARD TO STOP QUICKLY.

TRUE
FALSE (Correct answer)

Correct answer: FALSE

If a tire blows out, you should not put the brakes on hard. Applying the brakes forcefully can cause the vehicle to swerve violently or lose control, especially if it's a front tire. Instead, you should hold the steering wheel firmly, ease off the accelerator, and allow the vehicle to slow down gradually before gently applying the brakes to pull over safely.

Question 4: WHAT IS THE MINIMUM NUMBER OF TIE DOWNS FOR A 20 FOOT LOAD?

At least one tie down for every 20 feet
At least two tie downs for every 10 feet
At least one tie down for every 5 feet
At least one tie down for every 10 feet (Correct answer)

Correct answer: At least one tie down for every 10 feet

Federal regulations require a minimum number of tie-downs to secure cargo properly. For loads that are 10 feet or shorter, at least two tie-downs are needed. For loads longer than 10 feet, there must be at least one tie-down for every 10 feet of cargo length, in addition to two tie-downs for the first 10 feet. Therefore, a 20-foot load would require at least one tie-down for every 10 feet, meaning a minimum of two tie-downs (one for the first 10 feet and one for the second 10 feet), plus two additional tie-downs for the first 10 feet, totaling four tie-downs, but the question asks for 'at least one tie down for every 10 feet' as the general rule for longer loads.

Question 5: WHICH STATEMENT IS TRUE ABOUT REAR DRIVE-WHEEL BRAKING SKIDS?

When pulling a trailer, the trailer can push the towing vehicle sideways (Correct answer)
The locked wheels have more traction than the ones that are rolling
It is not a cause of jackknifing
The vehicles front wheels will slide sideways

Correct answer: When pulling a trailer, the trailer can push the towing vehicle sideways

Rear drive-wheel braking skids are particularly dangerous when pulling a trailer because the trailer's momentum can push the towing vehicle sideways. This phenomenon is known as jackknifing, where the trailer swings out and forms an acute angle with the tractor. The locked rear wheels of the tractor lose traction, making it impossible to control the direction of the vehicle as the trailer continues to push it.

Question 6: WHAT IS THE "GROSS COMBINATION WEIGHT" (GCW)?

Weight of cargo, plus weight of drivers and passengers
The maximum weight specified by the manufacturer that a vehicle can hold
Weight of trailer plus weight of cargo
Weight of power unit, plus trailer, plus cargo (Correct answer)

Correct answer: Weight of power unit, plus trailer, plus cargo

Gross Combination Weight (GCW) refers to the total weight of a power unit (the truck or tractor), its trailer(s), and all the cargo being carried. It represents the combined actual weight of the entire vehicle combination at a given time. This is distinct from Gross Combination Weight Rating (GCWR), which is the maximum weight specified by the manufacturer.

Question 7: FOR WHAT THREE THINGS RELATED TO CARGO ARE DRIVERS RESPONSIBLE?

Size of cargo, where cargo is placed, and unbalanced cargo
Inspection of cargo, balanced weight of cargo, secured cargo (Correct answer)
Secured cargo, inspection of sealed cargo, balanced weight of cargo
Inspection of a sealed container, balanced weight of cargo, where cargo is placed

Correct answer: Inspection of cargo, balanced weight of cargo, secured cargo

Commercial drivers have significant responsibilities regarding their cargo to ensure safety and compliance. They must inspect the cargo before, during, and after the trip to ensure it is properly loaded and secured. Additionally, drivers are responsible for ensuring the cargo's weight is balanced correctly to maintain vehicle stability and prevent overloading, and that all cargo is securely tied down to prevent shifting or falling.

Question 8: STAB BRAKING SHOULD NOT BE USED ON VEHICLES:

Hauling hazardous materials
Equipped with air brakes
Towing trailers
Equipped with anti-lock brakes (Correct answer)

Correct answer: Equipped with anti-lock brakes

Stab braking is a technique used to stop quickly by applying the brakes fully until the wheels lock, then releasing them when the wheels start to skid, and reapplying. However, this technique should NOT be used on vehicles equipped with anti-lock brakes (ABS). ABS systems are designed to automatically modulate brake pressure to prevent wheel lock-up, effectively performing the 'stab' and 'release' action much faster and more efficiently than a human driver, making manual stab braking unnecessary and potentially counterproductive.

Question 9: WHAT ARE THE 2 MAIN THINGS TO LOOK FOR AHEAD?

Traffic and road conditions (Correct answer)
Vehicles and stoplights
Disabled vehicles and obstacles
Curves and potholes

Correct answer: Traffic and road conditions

When driving, especially a large commercial vehicle, it is crucial to constantly scan the road ahead for potential hazards and changing conditions. The two main things to look for are traffic conditions, including other vehicles, pedestrians, and potential congestion, and road conditions, such as potholes, construction zones, curves, and slippery surfaces. This proactive scanning allows drivers to anticipate problems and react safely.

Question 10: HOW MANY REFLECTIVE TRIANGLES SHOULD YOU CARRY?

2
4
1
3 (Correct answer)

Correct answer: 3

Federal regulations require commercial vehicles to carry a minimum of three reflective warning triangles. These triangles are essential safety equipment used to warn other motorists of a stopped or disabled vehicle, especially during emergencies or breakdowns. They should be placed at specific distances behind the vehicle to provide adequate warning.

Question 11: WHAT IS A PULL-UP?

Re-positioning of your vehicle when backing (Correct answer)
A replacement for backing
Short forward movement to save brake wear
A Diaper

Correct answer: Re-positioning of your vehicle when backing

A 'pull-up' is a maneuver used when backing a large vehicle, particularly a tractor-trailer. It involves moving the vehicle forward a short distance to straighten out the trailer or adjust its angle relative to the tractor. This allows the driver to correct their alignment and continue backing more effectively, making it an essential skill for precise maneuvering in tight spaces.

Question 12: NAME SOME THINGS YOU SHOULD CHECK ON THE FRONT OF YOUR VEHICLE DURING THE WALK AROUND INSPECTION?

Fuel tank, engine, tires
Brakes, air lines, suspension
Signal and clearance lights, headlights (Correct answer)
Cab area, coupling system, rims

Correct answer: Signal and clearance lights, headlights

During the pre-trip inspection, checking the front of your vehicle is critical for safety. Key components to inspect include the signal lights, clearance lights, and headlights to ensure they are clean, operational, and properly aimed. These lights are vital for visibility and communicating your intentions to other drivers, especially in varying light and weather conditions.

Question 13: HOW OFTEN WHILE ON THE ROAD MUST YOU STOP TO INSPECT YOUR CARGO?

Every 1 hour or 50 miles
Every 3 hours or 150 miles (Correct answer)
Every 6 hours or 300 miles
Before and after your trip

Correct answer: Every 3 hours or 150 miles

To ensure cargo remains secure and balanced throughout a trip, federal regulations mandate periodic inspections while on the road. Drivers must stop and inspect their cargo within the first 50 miles of a trip, and then every 3 hours or 150 miles, whichever comes first. This regular check helps prevent shifting loads, which can affect vehicle handling and safety.

Question 14: STOPPING IS NOT ALWAYS THE SAFEST THING TO DO IN AN EMERGENCY.

TRUE (Correct answer)
FALSE

Correct answer: TRUE

In an emergency situation, stopping is not always the safest or most effective course of action. Sometimes, steering to avoid an obstacle or hazard, or accelerating to get out of a dangerous situation, might be a better option than attempting to stop. Drivers must quickly assess the situation and choose the action that minimizes risk and prevents a collision.

Question 15: WHAT FACTORS DETERMINE YOUR SELECTION OF A "SAFE" SPEED WHEN GOING DOWN A LONG, STEEP DOWNGRADE?

Speed/ space/ distance / perception
Reaction time/ distance/ speed/ vehicle size
Weight of vehicle/ length of grade/ steepness/ road conditions/ weather (Correct answer)
Perception/ reaction/ speed of vehicle/ stopping distance

Correct answer: Weight of vehicle/ length of grade/ steepness/ road conditions/ weather

Selecting a safe speed when descending a long, steep downgrade is crucial for preventing runaway vehicles and maintaining control. Several factors must be considered: the weight of the vehicle (heavier vehicles build speed faster), the length and steepness of the grade, and prevailing road and weather conditions (e.g., wet, icy, or winding roads). Drivers should use a low gear and engine braking to control speed, not just the service brakes.

Question 16: THE FIRST OFFENSE FOR DRIVING A COMMERCIAL VEHICLE UNDER THE INFLUENCE OF DRUGS OR ALCOHOL WILL CAUSE YOU TO LOSE YOUR CDL FOR:

6 months
2 years
1 year (Correct answer)
3 years

Correct answer: 1 year

The first offense for driving a commercial vehicle under the influence of drugs or alcohol results in a mandatory disqualification of your Commercial Driver's License (CDL) for a minimum of one year. This severe penalty underscores the strict regulations and zero-tolerance policy for impaired driving in the commercial trucking industry, prioritizing public safety.

Question 17: NAME A SUSPENSION SYSTEM DEFECT

Leaking shock absorbers (Correct answer)
Under-inflated tires
Loose lug nuts
Cracked brake cylinder

Correct answer: Leaking shock absorbers

A leaking shock absorber is a clear indication of a defect in the suspension system. Shock absorbers are vital for controlling spring action and maintaining tire contact with the road. A leak means the shock absorber is failing, which can lead to poor handling, reduced stability, and increased stopping distances, making it a serious safety concern.

Question 18: IF YOUR VEHICLE IS 40 FEET LONG AND YOU ARE TRAVELING AT 50 MPH, WHAT IS THE SAFE FOLLOWING DISTANCE?

3 seconds
4 seconds
7 seconds
5 seconds (Correct answer)

Correct answer: 5 seconds

The general rule for safe following distance for commercial vehicles is one second for every 10 feet of vehicle length at speeds under 40 mph, plus an additional second if traveling over 40 mph. For a 40-foot vehicle at 50 mph, this means 4 seconds for length (40 feet / 10 feet per second) plus 1 second for speed, totaling 5 seconds. This provides adequate time to react and stop safely.

Question 19: EMPTY COMMERCIAL TRUCKS HAVE THE BEST BRAKING.

TRUE
FALSE (Correct answer)

Correct answer: FALSE

This statement is false. Empty commercial trucks generally have worse braking performance than loaded trucks. When a truck is empty, there is less weight over the drive wheels, which reduces traction. This can cause the wheels to lock up more easily during braking, leading to skids and loss of control, especially on slippery surfaces. Loaded trucks have better traction due to the weight distribution.

Question 20: WHAT IS THE MINIMUM TREAD DEPTH FOR TIRES NOT INSTALLED IN THE FRONT?

4/32 inch
2/32 inch (Correct answer)
7/16 inch
3/8 inch

Correct answer: 2/32 inch

Federal regulations specify minimum tread depths for commercial vehicle tires to ensure adequate traction and safety. For tires not installed on the front steering axle, the minimum tread depth is 2/32 inch. Front steering axle tires have a stricter requirement of 4/32 inch due to their critical role in steering control.

Alabama General Knowledge CDL Practice Test

WHAT KIND OF FIRE IS A B:C EXTINGUISHER GOOD FOR?