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Drivers who want to drive combination vehicles must pass the combination vehicles test. The Texas CDL combination test consists of 20 questions, and you'll need at least 16 correct answers to pass (80%). The test covers the combination vehicles section of the Texas CDL Manual. Take this practice test now to prepare for the actual TX CDL combination test!
1. When uncoupling a trailer, after shutting off the trailer air supply to lock the trailer brakes, you should:
pull the tractor forward until the fifth-wheel comes out from under the trailer.
back up gently to ease the pressure on the fifth-wheel locking jaws.
immediately apply your tractor parking brakes.
inspect the trailer supports.
2. When more cargo is piled up in a truck, the center of gravity moves:
to the left side of the truck.
closer to the ground.
to the right side of the truck.
higher up from the road.
3. You are driving on a steep downgrade in the proper low gear. Your "safe" speed is 40 mph. When your speed reaches 40 mph, you should:
apply the brakes to gradually reduce your speed to 35 mph, and then release the brakes.
maintain your current speed, and apply the brakes when you reach 50 mph to gradually reduce your speed to 40 mph.
increase your speed to approximately 45 mph, and then apply release the brakes.
apply the brakes to quickly reduce your speed to 25 mph, and then release the brakes.
4. If you let air out of hot tires:
the tires will cool off much sooner.
as the tire cools, the air pressure will be too low.
air pressure will increases, causing the tires to blow out.
None of the above.
5. Broken suspension parts can be very dangerous. When inspecting your vehicle for suspension system defects, look for:
Broken leaves in a multi-leaf spring.
Spring hangers that allow movement of axle from proper position.
Damaged air suspension systems.
All of the above.
6. Empty trucks:
have better traction than fully-loaded trucks.
require shorter stopping distances than fully-loaded trucks.
may have poor traction.
None of the above.
7. After starting the engine, the ABS light stays on. This means:
the ABS is in Neutral.
the ABS is working properly.
the ABS is not working properly.
the ABS oil level is not adequate.
8. Glad hands are:
warning devices.
electronic devices.
securement devices.
coupling devices.
9. Foundation brakes are used:
at each wheel.
only with the right wheels.
only with the front wheels.
only with the rear wheels.
10. When backing a tractor under a trailer:
the end of the kingpin will be even with the top of the fifth wheel.
you should lift the trailer off the fifth-wheel.
the trailer will be lifted slightly when the tractor backs under it.
the fifth-wheel will come out from under the trailer.
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CDL Combination Test (TX)

Number of questions: 20
Correct answers to pass:16
Passing score:80%
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