Combination
Directions
All applicants who are applying for a Class A CDL should be prepared to take the Combination test. This test covers information found in Section 6 of the Texas Commercial Motor Vehicle Drivers Handbook. Section 6 provides the information needed to safely operate tractor-trailers, doubles, triples, and straight trucks with trailers. The test is made up of 20 multiple-choice questions, and applicants will need to correctly answer a minimum of 16 questions to pass. The Combination test is not a replacement for the Double/Triple endorsement test.
Passing grade:
Driving a combination vehicle ____ than driving a single vehicle.
Explanation
Driving a combination vehicle usually requires more skill than driving a single vehicle. Combination vehicles are generally longer and heavier than single commercial vehicles.
The easiest way to recognize that your trailer has begun to skid is to:
Explanation
The easiest way to spot a trailer skid is to use your mirrors. Any time you brake hard, check your mirrors to ensure that your trailer is still in its proper position.
When coupling a trailer:
Explanation
When coupling, make sure you couple matching glad hands. They are often color-coded to help drivers avoid mistakes. Typically, blue is used for service lines and red is used for emergency lines.
The trailer hand valve:
Explanation
The trailer hand valve should not be used for parking. This could cause all of the air to leak out of the braking system, resulting in the brakes releasing. Instead, use the parking brake.
Using the trailer hand valve while driving:
Explanation
Never use the trailer hand valve while operating your vehicle. Using the trailer hand valve while driving can cause your trailer to skid.
An air supply control in its "emergency" position will:
Explanation
Tractor protection controls in older vehicles may be operated by levers instead of knobs. If an air supply control is set in its "emergency" position, the air supply will be stopped and the trailer emergency brakes will be applied.
Which type of vehicle is most prone to the “crack-the-whip” effect?
Explanation
