CDL General Knowledge Practice Test 2026: Test de práctica 3

Test de práctica 3 de 6 de CDL General Knowledge Practice Test: 25 preguntas más con respuestas y explicaciones.

Vehículo comercial
Estados Unidos
150 preguntas
Revisado el 10 de octubre de 2026

Pregunta 1 de 25
Is a radar detector allowed in a commercial motor vehicle?
- Yes, if it is turned off
- Yes, on interstate highways
- Only in states that allow them
- No
Ver respuesta
Respuesta: D. No
A driver may not use a radar detector in a CMV or drive a CMV that has one in it.
Pregunta 2 de 25
In the seven-step inspection method, what is the first step?
- Vehicle overview
- Check the signal lights
- Check the brakes
- Check the engine compartment
Ver respuesta
Respuesta: A. Vehicle overview
Step 1 is the vehicle overview: general condition, leaning, leaks, hazards nearby and the last inspection report.
Pregunta 3 de 25
Before you check the engine compartment, what should you do?
- Turn on the high beams and flashers
- Start the engine and let it warm up
- Set the parking brake or chock the wheels
- Release the parking brake fully
Ver respuesta
Respuesta: C. Set the parking brake or chock the wheels
Step 2 starts by making sure the vehicle cannot move: set the parking brake and/or chock the wheels.
Pregunta 4 de 25
In which step of the seven-step inspection do you check tires, wheels, suspension and brakes on each side of the vehicle?
- Step 6, the signal lights
- Step 1, the overview
- Step 3, inside the cab
- Step 5, the walkaround
Ver respuesta
Respuesta: D. Step 5, the walkaround
The walkaround in step 5 covers lights, tires, wheels, suspension, brakes, cargo securement and fuel tanks on every side.
Pregunta 5 de 25
What is the last step of the seven-step inspection?
- Read the last inspection report
- Check the engine oil
- Walk around the vehicle
- Start the engine and check the brakes
Ver respuesta
Respuesta: D. Start the engine and check the brakes
Step 7 is to start the engine and check the brake system, including the parking brake and service brake tests.
Pregunta 6 de 25
What is the minimum tread depth for the front (steering) tires?
- 4/32 inch in every major groove
- 1/32 inch in every major groove
- 6/32 inch in every major groove
- 2/32 inch in every major groove
Ver respuesta
Respuesta: A. 4/32 inch in every major groove
Front tires need at least 4/32 inch of tread in every major groove.
Pregunta 7 de 25
What is the minimum tread depth for tires that are not on the front axle?
- 4/32 inch
- 6/32 inch
- 2/32 inch
- 1/32 inch
Ver respuesta
Respuesta: C. 2/32 inch
Tires other than the front tires need at least 2/32 inch of tread in every major groove.
Pregunta 8 de 25
How much play in the steering wheel can make the vehicle hard to steer?
- More than 45 degrees (about 8 inches on the rim)
- Any play at all, even less than a quarter inch
- More than 2 degrees (about half an inch on the rim)
- More than 10 degrees (about 2 inches on a 20-inch wheel)
Ver respuesta
Respuesta: D. More than 10 degrees (about 2 inches on a 20-inch wheel)
Steering wheel play of more than 10 degrees can make it hard to steer.
Pregunta 9 de 25
How do you check hydraulic brakes during the inspection?
- Drive at 30 mph and brake hard; the truck should stop straight
- Pump three times, then hold for five seconds; the pedal should not move
- Hold the pedal for one minute with the engine off; it should sink
- Press the pedal once quickly; it should spring back up right away
Ver respuesta
Respuesta: B. Pump three times, then hold for five seconds; the pedal should not move
With hydraulic brakes, pump three times and hold for five seconds. The pedal should stay firm.
Pregunta 10 de 25
How do you test the service brakes at the end of the inspection?
- Move forward at about 5 mph and brake firmly
- Apply the parking brake while moving
- Pump the pedal several times while parked
- Drive at highway speed and brake hard
Ver respuesta
Respuesta: A. Move forward at about 5 mph and brake firmly
Go forward slowly, about 5 mph, then brake firmly. Note any pulling or delay.
Pregunta 11 de 25
How do you check that the parking brake will hold?
- Push against the truck by hand from behind
- Set it and gently pull against it in a low gear
- Release it at highway speed and feel the pull
- Park on a steep hill and walk away to see
Ver respuesta
Respuesta: B. Set it and gently pull against it in a low gear
With the parking brake on, try to pull forward gently in a low gear. The vehicle should not move.
Pregunta 12 de 25
Which emergency equipment must a truck carry?
- A spare tire, a tow strap and jumper cables
- A fire extinguisher, warning devices and spare fuses
- Snow chains, a jack and a tire iron
- A first aid kit, a shovel and a flashlight
Ver respuesta
Respuesta: B. A fire extinguisher, warning devices and spare fuses
Required emergency equipment is a charged, rated fire extinguisher, warning devices such as three reflective triangles, and spare fuses unless the vehicle has circuit breakers.
Pregunta 13 de 25
Your oil pressure gauge shows low or falling pressure while you drive. What should you do?
- Speed up to raise the pressure
- Turn off the gauge
- Keep driving and check it at your next stop
- Stop as soon as it is safe
Ver respuesta
Respuesta: D. Stop as soon as it is safe
Low or changing oil pressure can mean engine damage. Stop right away when it is safe.
Pregunta 14 de 25
You find defects listed on the previous driver's inspection report. When should you sign the report?
- Only if the defects were repaired or certified as not needing repair
- Only at the end of your own trip, after you drive the vehicle
- Always, before you start the engine, whatever the report says
- Never; only a mechanic may sign an inspection report
Ver respuesta
Respuesta: A. Only if the defects were repaired or certified as not needing repair
Review the last report and sign it only when the defects listed were certified as repaired or not needing repair.
Pregunta 15 de 25
When you must back up, which way should you back if you have a choice?
- Into traffic
- Uphill
- Toward the driver's side
- Toward the right side
Ver respuesta
Respuesta: C. Toward the driver's side
Backing toward the driver's side lets you see better.
Pregunta 16 de 25
What does G.O.A.L. mean when backing?
- Get Out And Look
- Gear Options Are Limited
- Go Only At Low speed
- Give Others A Lane
Ver respuesta
Respuesta: A. Get Out And Look
Before and while backing, get out and look at your path if you are not sure what is behind you.
Pregunta 17 de 25
How should you back a large vehicle?
- Quickly, to finish the move
- In the highest reverse gear
- Slowly, in the lowest reverse gear
- In neutral, letting it roll
Ver respuesta
Respuesta: C. Slowly, in the lowest reverse gear
Back slowly in the lowest reverse gear so you can correct steering errors and stop quickly.
Pregunta 18 de 25
You are backing a trailer and want the trailer to go to the left. Which way do you turn the steering wheel?
- Hold it straight
- Turn it left, then quickly right
- To the left
- To the right
Ver respuesta
Respuesta: D. To the right
When backing a trailer, turn the steering wheel in the opposite direction from where you want the trailer to go.
Pregunta 19 de 25
Which kind of manual transmission usually needs double clutching?
- An unsynchronized transmission
- An automatic transmission
- A synchronized transmission
- Any transmission in top gear
Ver respuesta
Respuesta: A. An unsynchronized transmission
Unsynchronized manual transmissions usually need double clutching. Synchronized ones do not.
Pregunta 20 de 25
When should you downshift?
- After speed builds on a downgrade
- In the middle of a curve
- Before a downgrade and before a curve
- Only when the engine stalls
Ver respuesta
Respuesta: C. Before a downgrade and before a curve
Shift down before a downgrade and before a curve so you stay in control.
Pregunta 21 de 25
What should you do with a retarder on wet, icy or snowy roads?
- Set it to the highest level
- Use it instead of the brakes
- Turn it off
- Use it only in curves
Ver respuesta
Respuesta: C. Turn it off
Retarders can make the drive wheels skid on slippery roads, so turn them off.
Pregunta 22 de 25
Your drive wheels start to spin as you pull away. What should you do?
- Apply the trailer brakes
- Take your foot off the accelerator
- Shift into a higher gear quickly
- Press harder on the accelerator
Ver respuesta
Respuesta: B. Take your foot off the accelerator
If the drive wheels spin, ease off the accelerator to regain traction.
Pregunta 23 de 25
How far ahead do most good drivers look?
- 30 to 40 seconds
- 12 to 15 seconds
- 3 to 5 seconds
- 1 to 2 seconds
Ver respuesta
Respuesta: B. 12 to 15 seconds
Looking 12 to 15 seconds ahead gives you time to spot hazards and plan.
Pregunta 24 de 25
At highway speed, looking 12 to 15 seconds ahead means looking about how far?
- About 2 miles
- About 100 feet
- About one city block
- About a quarter of a mile
Ver respuesta
Respuesta: D. About a quarter of a mile
At lower speeds 12 to 15 seconds is about one block. At highway speeds it is about a quarter of a mile.
Pregunta 25 de 25
How do convex (curved) mirrors make objects look?
- Smaller and farther away than they really are
- Closer but the right size
- Larger and closer than they really are
- Exactly as they are
Ver respuesta
Respuesta: A. Smaller and farther away than they really are
Convex mirrors show a wider area, but things look smaller and farther away.

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