What topics are covered on the CDL Combination Vehicles knowledge test?

The CDL Combination Vehicles knowledge test covers: coupling and uncoupling procedures, braking system operation, trailer swing (jackknife) prevention, rollover avoidance, pre-trip inspection requirements, and more — based on Chapter 6 of the FMCSA Commercial Driver's License Standards.

What score do I need to pass the CDL Combination Vehicles written test?

Passing requirements vary by state, but most states require at least 80% correct to pass any CDL knowledge test. We recommend practicing until you consistently score 90% or higher before taking the official exam.

CDL Combination Vehicles Practice Test 3 (20 Questions with Explanations)

CDL Combination Vehicles · Practice Test 3

20 Questions · Detailed Answer Explanations

This free CDL Combination Vehicles practice test covers the most frequently tested topics including coupling and uncoupling procedures, trailer swing (jackknife) prevention, and braking systems and cargo distribution — all aligned with Chapter 6 of the FMCSA CDL manual.

Click any question number below to view the full explanation. We recommend working through the questions in order and aiming for a score of 90% or higher before scheduling your official CDL permit test.

Coupling & Uncoupling Trailer Swing Braking Systems Pre-Trip Inspection Cargo Distribution Rollover Prevention

About the CDL Combination Vehicles Knowledge Test

The CDL Combination Vehicles endorsement is required to operate semi-trucks, double trailers, and other combination vehicles. The written test is based on Chapter 6 of the FMCSA Commercial Driver's License Standards (49 CFR Part 383) and focuses on six core subject areas:

Coupling & Uncoupling: Step-by-step procedures for properly connecting and disconnecting the fifth wheel and trailer
Trailer Swing / Jackknife: Causes of trailer loss of control during sharp turns or hard braking — and how to prevent it
Braking Systems: Air brake coordination, brake lag, and how the Anti-Lock Braking System (ABS) works
Cargo Distribution: How center of gravity affects stability and axle weight compliance requirements
Rollover Prevention: Identifying risks from excessive speed in turns and cargo shift
Pre-Trip Inspection: Safety inspection items specific to combination vehicles

This practice test includes 20 questions weighted to reflect the actual exam, with a full explanation and manual section reference for every question. It's suitable for both first-time CDL applicants and those studying for a retake.