You arrive for your shift and the tractor was driven by another driver yesterday. Before you move the vehicle, what does the federal rule require you to do first?

Review the last driver vehicle inspection report and be satisfied the vehicle is in safe operating condition

Road test the vehicle for at least two miles before loading

Weigh the loaded vehicle at the nearest certified scale

Drain the air tanks and rebuild pressure from zero

Why is a leaking exhaust system a serious defect that must be corrected before driving?

Exhaust gas including carbon monoxide can enter the cab and poison the driver

It prevents the transmission from shifting into high gear

It automatically triggers the low-air-pressure warning

It always causes the engine to stall at highway speed

Which statement best describes the driver's legal responsibility before operating a commercial vehicle?

The driver must be satisfied that service brakes, parking brake, steering, lights, tires, horn, wipers, mirrors, coupling devices, wheels, and emergency equipment are in good working order

Only the motor carrier is responsible for vehicle condition

Responsibility begins only after the first 50 miles of the trip

The mechanic's signature transfers responsibility away from the driver

Which factors determine the safe speed for descending a mountain grade?

Total vehicle weight, length and steepness of the grade, road and weather conditions, and the amount of traffic

Only the type of brakes installed

You are entering a highway work zone with reduced lanes and workers present. What is the correct driving behavior?

Slow to the posted work-zone speed, increase following distance, avoid unnecessary lane changes, and watch for workers and equipment

Change lanes as often as needed to keep moving

Use the shoulder to bypass slow traffic

Maintain highway speed until you see a worker in the lane

Which sequence describes double clutching to shift into a higher gear?

Release the accelerator, push in the clutch and shift to neutral, release the clutch, let engine and gear speeds drop to the range for the next gear, push in the clutch and shift to the higher gear, release the clutch and accelerate

Accelerate hard, shift without the clutch, then brake

Shift to neutral, coast until the vehicle slows, then select any gear

Push in the clutch once, shift directly to the higher gear, and release the clutch

After uncoupling, you notice the landing gear crank handle is left extended. Why must it be secured?

An unsecured handle can catch on a passing vehicle or on the tractor and cause injury or damage

It affects the trailer air pressure

It changes the axle weight distribution

How can you tell that a tire has failed if you did not hear the blowout?

A thumping or vibration, a sudden change in steering feel, or the rear of the vehicle fishtailing

The air pressure gauge reads zero

What is the purpose of an electronic logging device on a commercial motor vehicle?

To automatically record driving time by connecting to the engine so hours-of-service records are accurate

To replace the requirement to keep any supporting documents

To measure axle weights while driving

To track fuel purchases for tax reporting only

CDL General Knowledge Practice Test

Preguntas frecuentes

¿Cuántas preguntas de práctica de Conocimientos Generales de CDL hay aquí?+

Un banco completo de preguntas originales de Conocimientos Generales de CDL en los temas centrales — conducción segura, inspección del vehículo, control del vehículo, emergencias y peligros, y regulaciones/salud del conductor — con el peso del examen real y explicaciones. Gratis, sin registro.

¿Cuántas preguntas tiene el examen real de Conocimientos Generales de CDL y cuál es el puntaje para aprobar?+

El examen de Conocimientos Generales suele tener unas 50 preguntas de opción múltiple, y debes acertar al menos el 80% para aprobar. El mínimo de 80% lo fija la regulación federal (49 CFR §383.135) y aplica en todos los estados, pero el número exacto de preguntas y los ítems específicos del estado varían según el DMV estatal.

¿El examen de Conocimientos Generales de CDL es igual en todos los estados?+

Las normas son federales, así que el requisito del 80% y los temas centrales son iguales en todo el país, pero cada estado escribe su propia versión a partir de su manual de CDL. Estudia siempre el manual de CDL de tu estado para el número exacto de preguntas y cualquier añadido estatal.

¿Son estas las preguntas reales del examen CDL?+

No. Cada pregunta es 100% original, escrita a partir de las regulaciones públicas de FMCSA y los manuales de CDL estatales. Nunca copiamos preguntas reales ni material de preparación pagado.

¿Puedo estudiar el material de CDL en chino o español?+

Sí — la práctica de PrepPass está en inglés, 中文 y español. Muchos DMV estatales ofrecen el examen de conocimientos de CDL en varios idiomas, pero puedes cambiar el idioma de las preguntas a inglés para ensayar la terminología exacta.

¿Todavía necesito el examen de Conocimientos Generales con la nueva regla ELDT?+

Sí. El Entrenamiento para Conductores Principiantes (ELDT) es un requisito de capacitación aparte; aún debes aprobar el examen de conocimientos de Conocimientos Generales de CDL (y las pruebas de endoso/habilidades correspondientes) en tu DMV estatal para obtener tu CDL.

Preguntas de práctica de ejemplo

Algunas preguntas reales de este banco gratuito, con explicaciones completas. Usa la herramienta de arriba para el banco completo.

1. Vehicle Inspection
You arrive for your shift and the tractor was driven by another driver yesterday. Before you move the vehicle, what does the federal rule require you to do first?
- a.Road test the vehicle for at least two miles before loading
- b.Review the last driver vehicle inspection report and be satisfied the vehicle is in safe operating condition
- c.Weigh the loaded vehicle at the nearest certified scale
- d.Drain the air tanks and rebuild pressure from zero
Respuesta: b
Explicación: A driver must review the previous driver's inspection report and sign it if defects were noted and certified as repaired, then be satisfied the vehicle is safe to operate. Draining tanks completely and rebuilding pressure is not a required daily step, weighing is a cargo issue rather than a pre-trip requirement, and no minimum road-test distance is required before loading.
Fuente: 49 CFR §396.13
2. Vehicle Inspection
Why is a leaking exhaust system a serious defect that must be corrected before driving?
- a.It prevents the transmission from shifting into high gear
- b.It automatically triggers the low-air-pressure warning
- c.It always causes the engine to stall at highway speed
- d.Exhaust gas including carbon monoxide can enter the cab and poison the driver
Respuesta: d
Explicación: Leaking exhaust can allow carbon monoxide and heat into the cab and can ignite nearby fuel or wiring, which is why it must be repaired before operating. Exhaust leaks do not stall the engine on their own, have nothing to do with air-pressure warnings, and do not lock out the transmission.
3. Vehicle Inspection
Which statement best describes the driver's legal responsibility before operating a commercial vehicle?
- a.The driver must be satisfied that service brakes, parking brake, steering, lights, tires, horn, wipers, mirrors, coupling devices, wheels, and emergency equipment are in good working order
- b.Only the motor carrier is responsible for vehicle condition
- c.Responsibility begins only after the first 50 miles of the trip
- d.The mechanic's signature transfers responsibility away from the driver
Respuesta: a
Explicación: The regulation places a personal duty on the driver to be satisfied that a specific list of components is in good working order before driving. A mechanic's signature and the carrier's own duties do not remove the driver's responsibility, and it applies from the first mile.
Fuente: 49 CFR §392.7
4. Safe Driving
Which factors determine the safe speed for descending a mountain grade?
- a.Only the size of the engine
- b.Only the type of brakes installed
- c.Total vehicle weight, length and steepness of the grade, road and weather conditions, and the amount of traffic
- d.Only the posted speed limit
Respuesta: c
Explicación: Safe descent speed depends on how much weight the brakes must control, how long and steep the grade is, and the conditions around you. A posted limit is a maximum for ideal conditions, and neither engine size nor brake type alone determines a safe speed.
5. Safe Driving
You are entering a highway work zone with reduced lanes and workers present. What is the correct driving behavior?
- a.Change lanes as often as needed to keep moving
- b.Use the shoulder to bypass slow traffic
- c.Slow to the posted work-zone speed, increase following distance, avoid unnecessary lane changes, and watch for workers and equipment
- d.Maintain highway speed until you see a worker in the lane
Respuesta: c
Explicación: Work zones combine narrowed lanes, sudden stops, and people on foot, so lower speed and extra space are essential, and fines are often doubled. Maintaining highway speed, weaving between lanes, and using the shoulder all increase the risk to workers and to you.
6. Control & Operation
Which sequence describes double clutching to shift into a higher gear?
- a.Accelerate hard, shift without the clutch, then brake
- b.Release the accelerator, push in the clutch and shift to neutral, release the clutch, let engine and gear speeds drop to the range for the next gear, push in the clutch and shift to the higher gear, release the clutch and accelerate
- c.Shift to neutral, coast until the vehicle slows, then select any gear
- d.Push in the clutch once, shift directly to the higher gear, and release the clutch
Respuesta: b
Explicación: Double clutching passes through neutral with the clutch released so engine and transmission speeds can match before the next gear is selected. Single clutching, floating gears without matching speeds, and coasting in neutral all grind gears or leave the vehicle without power control.
7. Control & Operation
After uncoupling, you notice the landing gear crank handle is left extended. Why must it be secured?
- a.An unsecured handle can catch on a passing vehicle or on the tractor and cause injury or damage
- b.It affects the trailer air pressure
- c.It changes the axle weight distribution
- d.It voids the inspection report
Respuesta: a
Explicación: A crank handle left hanging is a physical hazard that can strike people or equipment moving nearby. It has no effect on air pressure, weight distribution, or the validity of an inspection report.
8. Emergencies & Hazards
How can you tell that a tire has failed if you did not hear the blowout?
- a.The fuel gauge drops rapidly
- b.The air pressure gauge reads zero
- c.A thumping or vibration, a sudden change in steering feel, or the rear of the vehicle fishtailing
- d.The engine loses power
Respuesta: c
Explicación: Vibration, a pull in the steering when a front tire fails, or a fishtailing rear when a rear tire fails are the usual clues. Tire failure does not affect fuel level, brake system air pressure, or engine power.
9. Emergencies & Hazards
What is the maximum gross vehicle weight generally allowed on the Interstate highway system without a special permit?
- a.60,000 pounds
- b.100,000 pounds
- c.70,000 pounds
- d.80,000 pounds
Respuesta: d
Explicación: The federal limit is 80,000 pounds gross, with 20,000 pounds on a single axle and 34,000 pounds on a tandem axle set, subject to the bridge formula. Sixty and seventy thousand are below the legal maximum, and 100,000 pounds requires a permit.
10. Regulations & Health
What is the purpose of an electronic logging device on a commercial motor vehicle?
- a.To replace the requirement to keep any supporting documents
- b.To measure axle weights while driving
- c.To automatically record driving time by connecting to the engine so hours-of-service records are accurate
- d.To track fuel purchases for tax reporting only
Respuesta: c
Explicación: An ELD synchronizes with the engine to capture driving time automatically, which is why it replaced most paper logs. Fuel tax tracking and weight measurement are separate systems, and drivers must still retain supporting documents.
Fuente: 49 CFR §395.8

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