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Pennsylvania CDL General Knowledge study materials
Pennsylvania CDL General Knowledge study resources

Pennsylvania CDL General Knowledge practice questions

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Question 1General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

During a pre-trip inspection of a tractor-trailer, you check the slack adjusters on the service brakes. Which condition indicates the brakes need adjustment?

  1. The slack adjuster moves freely with the parking brake released
  2. The slack adjuster has a light film of lubricant on its splines
  3. The push rod extends less than 1 inch (25 mm) during a full application
  4. The push rod extends more than about 1 inch (25 mm) during a full application Correct answer.

Explanation

With the brakes fully applied and the system at normal pressure, a properly adjusted slack adjuster should allow no more than about 1 inch of push rod travel on a type-30 chamber. Excessive push rod travel means the brake shoes are far from the drum and the brakes will apply weakly or not at all. A light film of lubricant is normal, and free movement with the parking brake released is expected.

Question 2General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a loaded combination vehicle and need to stop quickly on a dry, level road. What is the most important reason to keep a following distance of at least one second for each 10 feet of your vehicle length?

  1. It prevents the trailer brakes from overheating
  2. It keeps you within the speed limit on downgrades
  3. It compensates for the much longer stopping distance of a heavy combination Correct answer.
  4. It allows you to use the engine brake more often

Explanation

The one-second-per-10-feet rule gives a following gap proportional to your total length, which is the practical way to account for the far greater stopping distance of a heavy combination vehicle. At highway speed a loaded rig needs substantially more road to stop than a passenger car. The rule has nothing to do with speed limits, trailer brake temperature, or engine brake use.

Question 3General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When backing a tractor-trailer, which technique gives you the most control?

  1. Turn the steering wheel sharply and hold it in one position
  2. Rely on the right mirror alone and ignore the left mirror
  3. Back quickly so the trailer does not have time to drift
  4. Back slowly and pull forward whenever the trailer drifts out of line Correct answer.

Explanation

Backing slowly gives you time to see and correct trailer drift, and pulling forward to reposition is the standard recovery when the trailer gets out of line. Fast backing magnifies every steering error. Holding the wheel in one position ignores the constant corrections a long combination needs, and using only one mirror hides hazards on the other side.

Question 4General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the proper way to use the retarder on a long downgrade?

  1. Select a gear low enough that the retarder and engine braking can hold your speed Correct answer.
  2. Apply the retarder only after the service brakes have faded
  3. Shift to neutral and let the retarder do all the work
  4. Use the highest gear so the retarder turns slowly

Explanation

On a long grade you choose a gear low enough that engine braking plus the retarder controls your speed without continuous service brake use. Coasting in neutral is illegal and dangerous because you lose engine braking and control. Waiting until the brakes fade is too late, and a high gear gives the retarder too little mechanical advantage.

Question 5General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You must cross railroad tracks and your vehicle has low ground clearance. What should you do?

  1. Stop on the tracks to look both ways more carefully
  2. Cross slowly in the lowest gear without checking the far side
  3. Cross at an angle if possible and check that the path is clear before starting Correct answer.
  4. Sound the horn and proceed without stopping

Explanation

Low-clearance vehicles can hang up on the rails, so you should cross at an angle when the road allows and make sure there is room to clear the tracks completely before you start. You should never stop on the tracks. Sounding the horn does not make the crossing safe if the far side is blocked.

Question 6General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

Which lights must be on when you are driving at night on a highway?

  1. Headlights and all required clearance, identification, and marker lights Correct answer.
  2. Parking lights alone
  3. High beams at all times
  4. Four-way flashers only

Explanation

At night you must operate with headlights on and all required clearance, identification, and marker lights illuminated so your vehicle is visible from every side. Parking lights alone do not provide enough illumination to see or be seen. Flashers are for emergencies, and high beams must be dimmed for oncoming traffic and when following.

Question 7General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a tanker with a partial load of liquid. What driving behavior does the surge of the liquid most affect?

  1. The brightness of the clearance lights
  2. Stopping distance and stability in curves and lane changes Correct answer.
  3. The accuracy of the speedometer
  4. Tire tread wear on the steer axle

Explanation

Liquid surge shifts weight forward and sideways, which lengthens stopping distance and can destabilize the vehicle in curves and quick lane changes. Smooth, gradual steering and braking are essential with a partial load. Surge does not affect tire wear rates, speedometer accuracy, or lighting.

Question 8General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

Where should you place the warning triangles when your vehicle is disabled on a divided highway?

  1. On the shoulder beside the cab only
  2. Directly in front of the vehicle only
  3. Behind the vehicle, starting about 10 feet away and spacing them back to about 100 feet Correct answer.
  4. At the nearest intersection in both directions

Explanation

On a divided highway place the triangles behind the vehicle, with the first about 10 feet back and the others spaced to roughly 100 feet so approaching drivers have time to react. Placing them only in front or beside the cab does nothing for traffic coming up behind you. Intersections are not the required placement point.

Question 9General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

Why should you avoid using the jake brake in a residential area or near a hospital?

  1. Local ordinances may prohibit engine brakes because of noise Correct answer.
  2. Engine brakes overheat the service brakes
  3. Engine brakes prevent the ABS from working
  4. Engine brakes damage the transmission in low gears

Explanation

Many municipalities restrict engine brakes in noise-sensitive areas such as residential zones and hospital districts, and violating the ordinance can bring a fine. The restriction is about noise, not mechanical harm. Engine brakes do not overheat service brakes or disable ABS.

Question 10General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are approaching a curve posted at a lower speed than the surrounding road. What is the safest approach?

  1. Slow to the posted speed before entering the curve and maintain steady speed through it Correct answer.
  2. Brake firmly in the middle of the curve to scrub speed
  3. Accelerate into the curve to increase traction
  4. Coast through the curve with the clutch disengaged

Explanation

The posted curve speed is the maximum safe speed for the curve, and a heavy vehicle should be slowed to it before the curve begins. Braking hard mid-curve can cause a skid or rollover, and accelerating into a curve increases the risk. Coasting with the clutch disengaged removes engine braking and control.

Question 11General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

A front tire blows out at highway speed while you are driving a loaded tractor-trailer. What should you do first?

  1. Steer sharply toward the shoulder to get off the road
  2. Hold the steering wheel firmly and keep the vehicle going straight while slowing gradually Correct answer.
  3. Release the steering wheel to let the vehicle correct itself
  4. Brake hard immediately to stop as quickly as possible

Explanation

With a front tire failure, the priority is to grip the wheel firmly and keep the vehicle straight while you slow gradually and then pull off the road. Hard braking can pull the vehicle toward the failed tire and cause a loss of control. Sharp steering at speed can cause a rollover, and releasing the wheel surrenders all control.

Question 12General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How does the stopping distance of a vehicle change when the road is wet?

  1. It increases because traction between the tires and the road is reduced Correct answer.
  2. It stays the same because ABS compensates for the water
  3. It is unaffected as long as the tires are properly inflated
  4. It decreases because water cools the brakes

Explanation

Wet pavement reduces the friction available between tire and road, so the vehicle needs more distance to stop. ABS helps prevent wheel lockup but cannot create traction that is not there. Water does not shorten stopping distance, and correct inflation does not restore lost grip on a wet surface.

Question 13General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a bus and must stop to load passengers on a busy street. What should you do before pulling back into traffic?

  1. Rely on the passengers to warn you of approaching vehicles
  2. Sound the horn and move out without checking mirrors
  3. Signal and pull out immediately to keep traffic moving
  4. Check both mirrors and the blind spots, signal, and re-check before moving Correct answer.

Explanation

Before re-entering traffic you must check both mirrors and the blind spots, signal your intention, and check again before moving out. Pulling out immediately or relying on passengers puts you in conflict with passing vehicles. Sounding the horn does not clear the lane.

Question 14General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the correct way to check that the trailer is securely coupled to the tractor after hooking up?

  1. Have someone stand behind the trailer while you accelerate
  2. Lower the landing gear and drive forward slowly
  3. Pull the tractor gently forward against the locked fifth wheel with the trailer brakes set Correct answer.
  4. Look at the coupling from the cab and assume it is locked

Explanation

The standard pull test is to set the trailer brakes and pull gently forward against the locked fifth wheel; if the coupling is secure the tractor will not move. Visual inspection alone from the cab is unreliable. Having someone behind the trailer is dangerous, and driving with the landing gear down can damage the gear and does not test the coupling.

Question 15General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When should you use the interaxle differential lock on a tractor with tandem drive axles?

  1. Continuously on the highway to reduce tire wear
  2. Whenever you back the trailer into a dock
  3. Only on slippery surfaces at low speed, and unlock it once traction is regained Correct answer.
  4. Whenever you drive on dry pavement to improve fuel economy

Explanation

The interaxle differential lock should be engaged only on slippery surfaces at low speed to get the vehicle moving, then disengaged once traction returns. Leaving it locked on dry pavement causes binding and tire and driveline damage. It is not a fuel-saving device, a docking aid, or something to leave engaged on the highway.

Question 16General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving in heavy fog and visibility drops sharply. What is the safest action?

  1. Slow down and use low beams, and pull off the road if visibility becomes too poor Correct answer.
  2. Use high beams so you can see farther ahead
  3. Turn on the four-way flashers and keep driving at the speed limit
  4. Increase speed to get through the fog quickly

Explanation

In fog you should slow down and use low beams, because high beams reflect off the moisture and make visibility worse. If conditions become too poor, pull well off the road and stop. Speeding up is dangerous, and running flashers while continuing at the speed limit does not address the loss of visibility.

Question 17General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What does the air compressor governor do in an air brake system?

  1. It sets the slack adjuster travel
  2. It controls when the compressor starts and stops pumping to maintain system pressure Correct answer.
  3. It releases air from the spring brakes
  4. It measures the amount of water in the tanks

Explanation

The governor senses system pressure and cuts the compressor in and out to keep the air pressure within a set range. It does not operate the spring brakes, measure tank moisture, or adjust the brakes. Those functions belong to other components.

Question 18General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are hauling a load of steel coils. Which securement practice is required?

  1. Use rope alone because steel is heavy
  2. Tighten the tiedowns once at the shipper and leave them for the trip
  3. Use tiedowns rated for the load and check them again shortly after starting out Correct answer.
  4. Rely on the weight of the coils to keep them in place

Explanation

Heavy steel coils require tiedowns with an aggregate working load limit sufficient for the cargo, and the load must be rechecked shortly after starting because tiedowns settle and loosen. Weight alone does not secure a load. Rope is generally inadequate for heavy steel, and tiedowns must be inspected during the trip.

Question 19General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are involved in a crash and must stop. Which action is required first?

  1. Move your vehicle out of the way before checking anyone
  2. Drive to the nearest phone before stopping
  3. Leave the scene to find a police officer
  4. Stop, protect the scene, and check for injuries before moving anything Correct answer.

Explanation

After a crash you must stop, take steps to protect the scene from further collisions, and check for injuries before moving vehicles or leaving. Driving away to find a phone or leaving to find an officer can be a hit-and-run. Moving vehicles before checking for injuries can worsen the situation.

Question 20General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the purpose of the tractor protection valve?

  1. It regulates the trailer's electrical voltage
  2. It controls the trailer's suspension height
  3. It closes the air line to the trailer if pressure drops, helping prevent a trailer breakaway Correct answer.
  4. It locks the fifth wheel jaws

Explanation

The tractor protection valve shuts off air to the trailer when system pressure falls too low, which helps keep the tractor's air supply from being lost through a separated or damaged trailer line. It has no role in trailer voltage, fifth wheel locking, or suspension height.

Question 21General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a 70-foot combination vehicle at 55 mph and want to change lanes. What is the most important space-management consideration?

  1. You need a much larger gap than a car because of your length and slower response Correct answer.
  2. You should change lanes only while accelerating hard
  3. You should change lanes without signaling to avoid startling drivers
  4. You can change lanes as quickly as a passenger car

Explanation

A long combination occupies far more lane space and takes longer to complete a lane change, so you need a substantially larger gap and must signal early. A heavy vehicle cannot maneuver like a car. Skipping the signal and accelerating hard both increase risk.

Question 22General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

A driver descends a long grade and the service brakes begin to fade. What is the best response?

  1. Downshift to a lower gear and use the retarder to slow down while continuing to brake firmly as needed Correct answer.
  2. Pump the brakes rapidly and continue in the same gear
  3. Apply the parking brake to slow the vehicle
  4. Shift to neutral and coast to the bottom

Explanation

Brake fade means the brakes are overheating and losing effectiveness; downshifting to a lower gear and using the retarder restores braking force without adding more heat. Pumping the brakes in the same gear does not solve the heat problem. Coasting in neutral removes engine braking, and the parking brake is not designed to stop a moving heavy vehicle.

Question 23General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a double trailer and need to make a right turn at an intersection. What must you account for?

  1. The rear trailer brakes independently and will stop the turn
  2. The rear trailer off-tracks farther than a single trailer, so you need more room and a wider turn Correct answer.
  3. The rear trailer swings toward the inside of the turn
  4. The rear trailer follows the tractor exactly, so a tight turn is safe

Explanation

With doubles, the rear trailer off-tracks farther inside the turn than a single trailer, so you must swing wider and allow more room to avoid hitting the curb or a vehicle. The rear trailer does not follow the tractor exactly, does not swing to the inside, and does not brake independently to control the turn.

Question 24General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How does a high center of gravity affect a loaded vehicle's rollover risk during a turn?

  1. It decreases the risk because the load presses down on the tires
  2. It increases the risk because the load's weight shifts outward and lifts the inside wheels sooner Correct answer.
  3. It increases traction and allows a faster turn
  4. It has no effect as long as the tires are properly inflated

Explanation

A high center of gravity means the vehicle's weight transfers outward more strongly in a turn, so the inside wheels can lift at a lower speed and the vehicle can roll over. The effect is independent of tire inflation, and it does not improve traction or allow faster turns.

Question 25General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving at night and an oncoming vehicle's high beams blind you. What is the safest response?

  1. Look directly at the oncoming headlights to judge the distance
  2. Turn on your high beams to retaliate
  3. Look toward the right edge of your lane and slow down until the vehicle passes Correct answer.
  4. Close your eyes briefly until the glare passes

Explanation

When glare from oncoming high beams blinds you, look toward the right edge of your lane and reduce speed until the vehicle passes. Staring at the lights worsens the glare, and retaliating with high beams blinds the other driver. Closing your eyes, even briefly, is extremely dangerous.

Question 26General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

During a pre-trip inspection of a commercial vehicle with air brakes, how much air pressure loss is allowed when the engine is off and the brakes are fully applied for one minute?

  1. No more than 25 psi
  2. No more than 3 psi Correct answer.
  3. No more than 10 psi
  4. No more than 20 psi

Explanation

For a single vehicle or a combination, the air brake leak test allows a loss of no more than 3 psi in one minute with the engine off and the service brakes fully applied. A larger drop means a leak that must be found and repaired before the vehicle is driven.

Question 27General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When you check the engine compartment during a pre-trip inspection, which condition on a power steering belt means the vehicle should be placed out of service?

  1. The belt has slight surface glazing
  2. The belt has frayed edges or cracks deeper than the fabric Correct answer.
  3. The belt shows its manufacturer markings
  4. The belt is slightly dusty

Explanation

A power steering belt with frayed edges, deep cracks, or missing chunks can fail and cause loss of steering assist, so it must be replaced before driving. Minor surface glazing, dust, or printed markings are not defects by themselves.

Question 28General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the proper way to hold the steering wheel for normal driving of a large commercial vehicle?

  1. Both hands on the wheel on opposite sides Correct answer.
  2. One hand at the bottom of the wheel
  3. One hand at the top of the wheel
  4. Both hands at the very top of the wheel

Explanation

Holding the wheel with both hands on opposite sides gives the best control and lets you turn quickly in an emergency. Hands at the top or bottom of the wheel reduce control and can be dangerous if the wheel kicks back.

Question 29General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

Why should you avoid riding the clutch or resting your foot on the clutch pedal while driving a manual-transmission truck?

  1. It reduces the load on the transmission
  2. It causes the clutch to slip and wear out prematurely Correct answer.
  3. It improves fuel economy at highway speeds
  4. It increases engine oil consumption

Explanation

Resting a foot on the clutch pedal keeps the clutch partially disengaged, so it slips and wears rapidly and can overheat. The clutch should be fully engaged or fully depressed, never held in between while driving.

Question 30General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When backing a tractor-trailer, what is the correct use of the mirrors?

  1. Look over your right shoulder instead of using mirrors
  2. Rely on the backup alarm to warn you of obstacles
  3. Use both mirrors to watch the rear corners of the trailer and the path behind Correct answer.
  4. Look only in the left mirror throughout the maneuver

Explanation

Backing requires constant reference to both mirrors so you can see the trailer's rear corners and the space behind the vehicle. The trailer responds to steering input in the opposite direction from a car, so visual feedback from both sides is essential.

Question 31General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How far ahead should you look while driving a commercial vehicle at highway speed?

  1. About 12 to 15 seconds of travel Correct answer.
  2. About four seconds of travel
  3. About one second of travel
  4. About 30 seconds of travel

Explanation

At highway speed you should look well down the road, roughly 12 to 15 seconds of travel time ahead, to spot hazards early. This lets you adjust speed and lane position smoothly instead of reacting suddenly.

Question 32General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When should a commercial driver use the four-way flashers while driving?

  1. Whenever the vehicle is moving slower than the posted speed limit
  2. When the vehicle is disabled or moving very slowly and is a hazard to traffic Correct answer.
  3. When driving in a construction zone with a reduced speed limit
  4. When passing another vehicle on a two-lane road

Explanation

Four-way flashers are meant to warn other drivers that your vehicle is a hazard, such as when it is disabled or creeping along far below traffic speed. Using them during normal driving or passing can confuse other drivers about your intentions.

Question 33General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the minimum following distance recommended for a commercial vehicle traveling at 55 mph on a dry road?

  1. Ten seconds
  2. Two seconds
  3. One second
  4. Seven seconds Correct answer.

Explanation

The recommended rule is one second for each 10 feet of vehicle length plus one second, so a 60-foot combination needs about seven seconds at speeds above 40 mph. This space gives you time to react and stop a heavy vehicle safely.

Question 34General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving a loaded truck and need to stop on a downgrade. What is the safest practice?

  1. Apply the brakes firmly and hold them continuously
  2. Use a low gear and apply the brakes in short, firm applications Correct answer.
  3. Turn off the engine to save fuel while braking
  4. Shift to neutral and coast while braking

Explanation

Descending a grade in a low gear uses engine braking to help control speed, and short firm brake applications let the brakes cool between uses. Continuous braking or coasting in neutral can overheat the brakes and lead to fade or loss of control.

Question 35General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What does a flashing red light at a railroad crossing require you to do?

  1. Yield only to trains that sound a horn
  2. Stop, then proceed when it is safe Correct answer.
  3. Slow down and proceed if no train is visible
  4. Stop only if the gate is down

Explanation

A flashing red light at a railroad crossing means the same as a stop sign: you must come to a complete stop and proceed only when the tracks are clear. You should never rely on seeing or hearing a train before stopping.

Question 36General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When approaching a railroad crossing with a lowered gate and flashing lights, what should you do if your vehicle is long enough that the rear might still be on the tracks?

  1. Stop on the tracks and wait for the gate to lift
  2. Proceed slowly so the gate can rise behind you
  3. Wait until there is room to clear the tracks completely before starting across Correct answer.
  4. Back up onto the tracks to get a running start

Explanation

You should never start across a railroad crossing unless you can clear the tracks completely without stopping. Stopping on the tracks leaves your vehicle in the path of a train and is extremely dangerous.

Question 37General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What should you do if your headlights fail while driving at night?

  1. Flash your high beams to signal other drivers
  2. Continue driving using only the parking lights
  3. Turn on the four-way flashers, slow down, and pull off the road safely Correct answer.
  4. Speed up to reach the next exit quickly

Explanation

If your headlights fail at night, activate the four-way flashers, slow down, and move off the road as soon as it is safe. Continuing to drive without headlights makes your vehicle nearly invisible to others.

Question 38General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How should you adjust your speed when driving on packed snow or ice?

  1. Maintain the posted speed limit to keep traction
  2. Speed up to avoid getting stuck
  3. Reduce speed and increase following distance Correct answer.
  4. Use cruise control to keep a steady speed

Explanation

On packed snow or ice, traction is reduced, so you should slow down and leave much more space ahead. Gentle steering and braking inputs help prevent skids on slippery surfaces.

Question 39General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the correct action if your vehicle starts to hydroplane on a wet road?

  1. Turn the steering wheel back and forth to regain grip
  2. Accelerate to push through the water
  3. Brake hard and steer sharply to the shoulder
  4. Ease off the accelerator and steer gently without braking Correct answer.

Explanation

Hydroplaning happens when tires ride on a film of water and lose contact with the road. Easing off the accelerator lets the vehicle slow gradually and the tires regain contact, while hard braking or sharp steering can cause a skid.

Question 40General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What should you do before driving through a flooded roadway?

  1. Follow the vehicle ahead closely
  2. Shift to a higher gear and accelerate
  3. Check the depth and current, and turn around if you are unsure Correct answer.
  4. Drive through quickly to avoid stalling

Explanation

Flood water can hide washed-out pavement and can be deep enough to stall or float a vehicle. If you cannot clearly judge the depth and current, the safe choice is to turn around rather than risk being swept away.

Question 41General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What is the function of the slack adjusters in an air brake system?

  1. They release air from the system when pressure is too high
  2. They keep the brake shoes close to the drums as linings wear Correct answer.
  3. They measure air pressure in the tanks
  4. They lock the trailer brakes when the emergency line is cut

Explanation

Slack adjusters take up the gap between the brake shoes and drums as the linings wear, keeping the brakes responsive. If they are out of adjustment, the brakes may not apply fully and stopping distance increases.

Question 42General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How can you tell if a vehicle's brakes are out of adjustment during a pre-trip inspection?

  1. The pushrod stroke exceeds the adjustment limit Correct answer.
  2. The brake pedal feels firm when pressed
  3. The air pressure gauge reads above 100 psi
  4. The brake shoes have less than a quarter inch of lining

Explanation

A pushrod stroke longer than the adjustment limit means the brakes are out of adjustment and may not apply fully. Brake lining thickness and pedal feel are separate checks from the stroke measurement.

Question 43General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What must you do if the cargo on your flatbed is not secured properly before you drive?

  1. Drive slowly and secure it at the next stop
  2. Cover the load with a tarp and drive
  3. Secure the load before moving the vehicle Correct answer.
  4. Ask the shipper to secure it later

Explanation

Cargo must be properly secured before the vehicle moves; loose cargo can shift or fall and cause a crash. Securing it later or covering it with a tarp does not meet the requirement.

Question 44General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When loading cargo, why should you place the heaviest items as low as possible?

  1. To make loading faster
  2. To increase the payload capacity
  3. To reduce the need for tie-downs
  4. To lower the center of gravity and improve stability Correct answer.

Explanation

Keeping heavy items low lowers the center of gravity, which improves stability and reduces rollover risk. A high center of gravity makes a vehicle more likely to tip during turns or sudden maneuvers.

Question 45General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What should you do if a tire blows out on a rear axle of a loaded tractor-trailer?

  1. Hold the wheel firmly, ease off the accelerator, and slow gradually Correct answer.
  2. Accelerate to keep the trailer straight
  3. Release the steering wheel briefly to let the vehicle settle
  4. Brake hard immediately and steer off the road

Explanation

With a rear tire blowout, hold the wheel firmly, keep the vehicle straight, and ease off the accelerator so it slows gradually. Hard braking can cause a skid or loss of control, especially with a loaded trailer.

Question 46General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

When must you place warning triangles behind a disabled vehicle on a two-lane road?

  1. Only at night
  2. Within 10 minutes of stopping Correct answer.
  3. Only if the vehicle is carrying hazardous materials
  4. Only when the shoulder is narrow

Explanation

Warning devices must be placed within 10 minutes of stopping on a two-lane road, and they must be visible to approaching traffic. Placing them promptly gives other drivers time to slow and move over.

Question 47General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What should you do first if you are involved in a crash with a commercial vehicle and someone is injured?

  1. Move the injured person immediately
  2. Move your vehicle out of the way before helping
  3. Stop, protect the scene, and call for help Correct answer.
  4. Leave the scene to find the nearest phone

Explanation

After a crash, stop and stay at the scene, make the area safe, and call for emergency help. Moving an injured person without training can make injuries worse, and leaving the scene is illegal.

Question 48General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

How should you position a commercial vehicle when making a right turn at an intersection?

  1. Accelerate through the turn to clear the intersection quickly
  2. Swing wide to the left before turning
  3. Keep the rear wheels close to the curb to avoid hitting it Correct answer.
  4. Turn from the left lane to make a sharper turn

Explanation

A large vehicle's rear wheels track inside the front wheels, so keeping the rear wheels close to the curb prevents the trailer from hitting the curb or pedestrians. Swinging wide to the left can confuse other drivers and block traffic.

Question 49General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

What does the term 'space cushion' mean for a commercial driver?

  1. The distance between the axles of the tractor
  2. The gap between the trailer and the dock
  3. The padded area inside the cab
  4. The distance kept between your vehicle and hazards around it Correct answer.

Explanation

A space cushion is the clear distance you keep around your vehicle so you have time to react to hazards ahead, behind, and to the sides. Managing that space is central to safe speed and following-distance decisions.

Question 50General Knowledge (vehicle inspection, basic control, shifting, backing, seeing, communication, speed management, space management, hazard perception, emergency maneuvers, railroad crossings, night driving, extreme driving conditions, vehicle systems, cargo, crash procedures)

You are driving at night and see a pedestrian walking along the edge of the road ahead. What should you do?

  1. Sound the horn continuously and maintain speed
  2. Slow down, move over if possible, and be ready to stop Correct answer.
  3. Flash your high beams and continue at the same speed
  4. Accelerate to pass the pedestrian quickly

Explanation

Pedestrians are hard to see at night, so slow down, give them room, and be prepared to stop. Sounding the horn or flashing lights can startle them, and speeding past reduces your reaction time.