Double
This endorsement is required if the driver will pull two or three trailers. To receive this endorsement, applicants must pass a test. The test consists of 20 multiple choice questions. To pass, the applicant must answer at least 16 questions correctly. Each question has three or four possible answer choices. Test questions come from the North Carolina Commercial Driver License Manual. Questions come from chapters covering: Driving Safely, Air Brakes (if applicable), Combination Vehicles and Doubles and Triples. The Double/Triple endorsement can be used with the Class A CDL.
Number of Question
Passing Score
1. Belts in the engine compartment should be:
Explanation
When inspecting your vehicle's engine, check the belts for tightness and excessive wear. The amount of "give" that is safe for each belt in a given engine will vary, so learn what is appropriate for your vehicle.
2. Fully-loaded rigs:
Explanation
Because the weight of cargo gives them a higher center of gravity, fully-loaded rigs are 10 times more likely to roll over in a crash than empty rigs.
3. When you leave your vehicle, you should:
Explanation
Always apply the parking brake when leaving your vehicle.
4. When using a fire extinguisher on a fire, you should:
Explanation
When using a fire extinguisher, you should stand as far away from the fire as possible. Aim the extinguisher at the base of the fire, not at the flames. If you are not sure which kind of extinguisher should be used on a fire, particularly a hazardous materials fire, you should wait for the firefighters to arrive and allow them to extinguish it.
5. The air compressor is connected to the:
Explanation
The air compressor of an air brake system is connected to the engine through gears or a v-belt. The compressor may be air-cooled or cooled by the engine cooling system.
6. If the emergency air line loses pressure:
Explanation
The tractor protection valve keeps air in the trailer's braking system should the trailer break away or develop a leak. A loss of air pressure in the emergency line will cause the tractor protection valve to open and the emergency trailer brakes to activate.
7. If the brakes “pull” to one side or the other when you use them, it's a sign that:
Explanation