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CDL Test Overview

CDL TestA Commercial Driver's License (CDL) is required by anyone who operates:

A vehicle with a Gross Vehicle Weight Rating of more than 26,000 pounds

A combination vehicle - where towing a vehicle with a GVWR of more than 10,000 pounds or a combination GVWR of more than 26,000 pounds

A vehicle intended to transport 16 or more people

A vehicle that carries hazardous materials (hazmat) in any amount requiring a placard

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In order to obtain your CDL, you will be required to pass a CDL test.  The CDL test is made up of several tests, including a general knowledge tests, several endorsement tests, and a air brakes test.  The type of vehicle you intend to drive (i.e., Passenger Bus, Tanker, Double/Triple etc.) and the license classification (Class A, B, or C) will determine which endorsements and tests you are required to take.  See the tables on the bottom of this page to determine which tests you are required to take.

Overview of CDL General Knowledge Test

Passing a General Knowledge CDL exam is required for every CDL license.  The General Knowledge exam will test you on the topics covered in your state CDL manual, such as:

  • Basic Control of Your Vehicle
  • Vehicle Inspection
  • Driving Safely
  • Communicating
  • Seeing
  • Shifting Gears
  • Seeing Hazards
  • Managing Space
  • Controlling Speed
  • Driving in Very Hot Weather
  • Driving in Winter
  • Driving in Fog
  • Driving at Night
  • Aggressive Drivers/Road Rage
  • Distracted Driving
  • Driving Emergencies
  • Mountain Driving
  • Railroad-highway Crossings
  • Crash Procedures
  • Skid Control and Recovery
  • Antilock Braking Systems (ABS)
  • Cargo Transport
  • Fires
  • Staying Alert and Fit to Drive
  • Alcohol, Other Drugs, and Driving
  • Hazardous Materials Rules For All Commercial Drivers

Endorsement Tests

Depending on the type of Commercial Motor Vehicle (CMV) you intend to drive, you must take and pass various endorsement tests. The endorsement tests are described below.

Double and triple trailer endorsement – Assesses your knowledge about driving safely with double and triple trailers.  Includes questions on how to couple and uncouple trailers and inspections.

Tank endorsement – You are required to have a tank endorsement if you plan on driving a CMW over 26,000 pounds that is used to transport liquid/gaseous materials.  The materials do not have to be hazardous.  This endorsement is only required if the vehicle is a Class A or B vehicle with a permanently mounted take greater than 119 gallons or a portable greater than 1,000 gallons.

Passenger endorsement – You will need to obtain a passenger endorsement if you plan on driving any vehicle designed to carry 16 or more persons, including the driver.  If the vehicle is a school bus, you will need to obtain an additional school bus endorsement.

School bus endorsement – Although these regulations may vary from state to state, you are required to have a school bus endorsement if you plan on driving a vehicle that carries 16 or more people, including the driver that is marked with or displays the words “school bus.” A school bus is used to transport students to or from school  or authorized school activities.  If the school bus is not transporting students, then a school bus manufacturer, dealer or mechanic is not required to have the endorsement. Before receiving a school bus endorsement, you must qualify for a passenger endorsement.

Hazardous materials endorsement – Hazardous Materials (HAZMAT) include explosives, flammable and combustible liquids and any materials that the shipper deems as hazardous. You must obtain a HAZMAT endorsement to operate any size vehicle that requires a HAZMAT placard.

Air Brakes Test

Air brakes use compressed air for their operation.  An air brakes system is comprised of three different braking systems: service brake, emergency brake and parking brake. When you receive your CDL, you will have an Air Brakes restriction until you take and pass the Air Brakes test.  This means that you cannot operate any CMV with air brakes until you pass the test.  The Air Brakes test will evaluate your knowledge of how to properly inspect, use and maintain your vehicle's air brakes.

Which Tests Should I Study For

The following table summarizes which exams you should study based on the license you plan on obtaining.

License Class

General Knowledge

Passenger Transport

Combination Vehicles

Hazardous Materials

Tanker

Double/
Triples

Air Brakes

Class A

X

 

X

If needed

If needed

If needed

X

Class B

X

If needed

 

If needed

If needed

 

If needed

Class C

X

If needed

 

If needed

If needed

 

 

Exam Summary

The following table summarizes the various exams.

Knowledge Test

Number of Questions

Questions required to get right to pass at 80%

General Knowledge Test

50

40

Passenger Transport Test

20

16

Combination Vehicles Test

20

16

Hazardous Materials Test

30

24

Tanker Test

20

16

Doubles/Triples Test

20

16

Air Brakes Test

25

20

Although formal training is not required to obtain a Commercial Driver's License, you must take and pass a CDL test.  The CDL requirements are based on national regulations, although each state may add additional restrictions.  To obtain your CDL license you must take and pass a general knowledge exam, and various endorsement tests depending on the type of vehicle you plan on operating.  In addition, you must pass a driving skills test by successfully performing a series of required maneuvers. 

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