Free CDL Double Triple Practice Test 2019

QUESTION NO: 1

To check that air flows to all trailers during the pre-trip inspection, wait for air pressure to reach normal, then __________
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A. push in the tractor protection valve control.
B. pull out the tractor protection valve control.
C. pull out the trailer air supply knob.
D. push in the trailer air supply knob.

Answer: D

Explanation:

Check the brakes on a double or triple trailer as you would any combination vehicle. You must make additional checks on your double or triple trailers. To check that air flows to all trailers (double and triple trailers) during your pre-trip inspection, use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for the air pressure to reach normal, then push in the red “trailer air supply” knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line.
Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged. Close the emergency line valve. Open the service line valve to check that service pressure goes through all the trailers (this test assumes that the trailer handbrake or the service brake pedal is on), and then close the valve. If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly(ies) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work.

QUESTION NO: 2

To couple the tractor and first semitrailer to the second and third trailers on a triple, __________
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A. couple the tractor to the first trailer.
B. move the converter dolly into position and couple the first trailer to the second trailer using the method for coupling doubles.
C. both A and B
D. neither A nor B

Answer: C

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Explanation:

To couple the tractor/first semitrailer to the second/third trailers, first couple the tractor to the first trailer. Use the same method you would use for coupling tractor-semitrailers. Move the converter dolly into position and couple the first trailer to the second trailer using the method for coupling doubles. The triples rig is now complete.

QUESTION NO: 3

To test the trailer emergency brakes during the pre-trip inspection, __________
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A. charge the trailer air brake system, shut the engine off, and step on and off the brake pedal several times to reduce the air pressure in the tanks.
B. pull out the trailer air supply control and pull gently on the trailer with the tractor.
C. check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and use the trolley valve.
D. none of the above

Answer: B
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Explanation:

During the pre-trip inspection of your combination vehicle, test the trailer emergency brakes. Charge the trailer air brake system and make sure the trailer rolls freely. Then stop and pull out the trailer air supply control (also called the tractor protection valve control or the trailer emergency valve) or place it in the “emergency” position. Pull gently on the trailer with the tractor to be sure the trailer emergency brakes are on.

QUESTION NO: 4

If the tractor protection valve doesn’t work correctly, an air hose or trailer brake leak could drain all the air from the tractor, causing the __________ brakes to come on.
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A. service
B. parking
C. emergency
D. none of the above

Answer: C Bottom of Form

Explanation:

During your pre-trip inspection on a combination vehicle, test the tractor protection valve. Charge the trailer air brake system. (that is, build up normal air pressure and push the “air supply” knob in). Shut the engine off. Step on and off the brake pedal several times to reduce the air pressure in the tanks. The trailer air supply control (also called the tractor protection valve control) should pop out (or go from “normal” to “emergency” position) when the air pressure falls into the pressure range specified by the manufacturer.
(Usually within the range of 20 to 45 psi). If the tractor protection valve doesn’t work properly, an air hose or trailer brake leak could drain all the air from the tractor. This would cause the emergency brakes to come on, with possible loss of control.

QUESTION NO: 5

To uncouple a converter dolly, release the pintle hook on the first semitrailer, then __________
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A. apply the converter gear spring brakes or chock the wheels.
B. slowly pull clear of the dolly.
C. lower the dolly landing gear.
D. disconnect the safety chains.

Answer: B Bottom of Form

Explanation:

To uncouple twin trailers, uncouple the converter dolly after uncoupling the rear trailer. Lower the dolly landing gear. Disconnect the safety chains. Apply the converter gear spring brakes or chock the wheels. Release the pintle hook on the first semi-trailer. Slowly pull clear of the dolly. Never unlock the pintle hook with the dolly still under the rear trailer. The dolly tow bar may fly up, possibly causing injury, and making it very difficult to re-couple.

QUESTION NO: 6

When you check the landing gear during the walkaround inspection, make sure that __________
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A. it is fully lowered, with no missing parts.
B. the crank handle is in place and secured.
C. both A and B
D. none of the above

Answer: B
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Explanation:

Use the Seven-step Inspection Method to inspect your combination vehicle. There are more things to inspect on a combination vehicle than on a single vehicle. Many of these items are simply more of what you would find on a single vehicle. (For example, tires, wheels, lights, reflectors, etc.) However, there are also some new things to check. During the walkaround inspection in step five, check the landing gear.
Make sure that it is fully raised, with no missing parts, and is not bent or otherwise damaged. Be sure the crank handle is in place and secured. If the landing gear is power operated, make sure there are no air or hydraulic leaks.

QUESTION NO: 7

When coupling a second trailer that doesn’t have __________ brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line.
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A. s-cam
B. wedge
C. emergency
D. springBottom of Form

Answer: D

Explanation:

Knowing how to couple and uncouple correctly is basic to safe operation of doubles and triples. Coupling and uncoupling incorrectly can be very dangerous. If you are coupling twin trailers and the second trailer doesn’t have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line. This will set the trailer emergency brakes (if the slack adjusters are correctly adjusted). Chock the wheels if you have any doubt about the brakes.

QUESTION NO: 8

When uncoupling the rear trailer of a double, release the dolly brakes, then __________
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A. slowly pull the tractor, first semitrailer, and dolly forward to pull the dolly out from under the rear semitrailer.
B. lower the dolly landing gear.
C. release the converter dolly fifth wheel latch.
D. none of the above

Answer: C
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Explanation:

To uncouple twin trailers, first uncouple the rear trailer. Park the rig in a straight line on firm, level ground. Apply the parking brakes so the rig won’t move. Chock the wheels of the second trailer if it doesn’t have spring brakes. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly. Close the air shut-offs at the rear of the first semitrailer (and on the dolly if so equipped).
Disconnect all dolly air and electric lines and secure them. Release the dolly brakes. Release the converter dolly fifth wheel latch. Slowly pull the tractor, first semitrailer, and dolly forward to pull the dolly out from under the rear semitrailer.
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QUESTION NO: 9

Which of the following statements is false?

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A. Look far ahead so you can slow down or change lanes gradually when necessary.
B. Doubles and triples take up less space than other commercial vehicles.
C. Doubles and triples need more space than other commercial vehicles because they can’t be turned or stopped suddenly.
D. none of the above

Answer: B

Explanation:

Doubles and triples must be driven very smoothly to avoid rollover or jackknife. Therefore, look far ahead so you can slow down or change lanes gradually when necessary. Doubles and triples take up more space than other commercial vehicles.
They are not only longer, but also need more space because they can’t be turned or stopped suddenly. Allow more following distance. Make sure you have large enough gaps before entering or crossing traffic. Be certain you are clear at the sides before changing lanes.

QUESTION NO: 10

When coupling a second trailer that doesn’t have spring brakes, drive the tractor close to the trailer,
connect the __________ line, charge the trailer air tank, and disconnect the __________ line.
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A. emergency, emergency
B. service, service
C. signal, signal
D. none of the aboveBottom of Form

Answer: A

Explanation:

Knowing how to couple and uncouple correctly is basic to safe operation of doubles and triples. Coupling and uncoupling incorrectly can be very dangerous.
If you are coupling twin trailers and the second trailer doesn’t have spring brakes, drive the tractor close to the trailer, connect the emergency line, charge the trailer air tank, and disconnect the emergency line.
This will set the trailer emergency brakes (if the slack adjusters are correctly adjusted). Chock the wheels if you have any doubt about the brakes.

QUESTION NO: 11

When connecting a converter dolly to the rear trailer of a twin trailer combination, trailer height should be slightly __________ than the center of the fifth wheel, so the trailer is __________ slightly when the dolly is pushed under.
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A. higher, raised
B. higher, lowered
C. lower, lowered
D. lower, raised

Answer: DBottom of Form

Explanation:

To connect a converter dolly to the rear trailer when coupling twin trailers, first make sure the trailer brakes are locked and/or wheels are chocked. Make sure the trailer height is correct. (It must be slightly lower than the center of the fifth wheel, so the trailer is raised slightly when the dolly is pushed under.) Back the converter dolly under the rear trailer.
Raise the landing gear slightly off the ground to prevent damage if the trailer moves. Test the coupling by pulling against the pin of the second semitrailer. Make a visual check of the coupling. (There should be no space between the upper and lower fifth wheel. The locking jaws should be closed on the kingpin.) Connect the safety chains, air hoses, and light cords. Close the converter dolly air tank petcock and shut-off valves at the rear of the second trailer (service and emergency shut-offs).
Open the shut-off valves at the rear of the first trailer (and on the dolly if so equipped). Raise the landing gear completely. Charge the trailers (push the “air supply” knob in) and check for air at the rear of the second trailer by opening the emergency line shut-off. If air pressure isn’t there, something is wrong and the brakes won’t work.

QUESTION NO: 12

When you conduct your walkaround inspection during the Seven-step Inspection Method, make sure the shut-off valves in the service and emergency lines at the rear of the last trailer are __________ and that the converter dolly air tank drain valve is __________
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A. open, open.
B. open, closed.
C. closed, open.
D. closed, closed.

Answer: D Bottom of Form

Explanation:

When you conduct your walkaround inspection during step five of the Seven-step Inspection Method, check the shut-off valves (at rear of trailers, in service and emergency lines). At the rear of the front trailers, they should be open. At the rear of the last trailer, they should be closed. The converter dolly air tank drain valve should be closed.
Be sure air lines are supported and glad hands are properly connected. If the spare tire is carried on the converter gear (dolly), make sure it is secure. Be sure the pintle-eye of the dolly is in place in the pintle hook of the trailer(s). Make sure the pintle hook is latched. Safety chains should be secured to trailer(s). Be sure the light cords are firmly in sockets on trailers.

QUESTION NO: 13

When you check that air flows to all trailers during the pre-trip inspection, __________ to hold the vehicle.
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A. use the tractor parking brake
B. chock the wheels
C. either A or B
D. neither A nor B

Answer: C Bottom of Form

Explanation:

Check the brakes on a double or triple trailer as you would any combination vehicle. You must make additional checks on your double or triple trailers. To check that air flows to all trailers (double and triple trailers) during your pre-trip inspection, use the tractor parking brake and/or chock the wheels to hold the vehicle.
Wait for the air pressure to reach normal, then push in the red “trailer air supply” knob. This will supply air to the emergency (supply) lines. Use the trailer handbrake to provide air to the service line. Go to the rear of the rig. Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping, showing the entire system is charged. Close the emergency line valve.
Open the service line valve to check that service pressure goes through all the trailers (this test assumes that the trailer handbrake or the service brake pedal is on), and then close the valve. If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailer(s) and dolly(ies) are in the OPEN position.
You MUST have air all the way to the back for all the brakes to work.

QUESTION NO: 14

When uncoupling the rear trailer of a double, which of the following should be done first?
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A. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
B. Apply the parking brakes so the rig won’t move.
C. Disconnect all dolly air and electric lines and secure them.
D. Release the converter dolly fifth wheel latch.

Answer: B Bottom of Form

Explanation:

To uncouple twin trailers, first uncouple the rear trailer. Park the rig in a straight line on firm, level ground. Apply the parking brakes so the rig won’t move. Chock the wheels of the second trailer if it doesn’t have spring brakes. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
Close the air shut-offs at the rear of the first semitrailer (and on the dolly if so equipped). Disconnect all dolly air and electric lines and secure them. Release the dolly brakes. Release the converter dolly fifth wheel latch. Slowly pull the tractor, first semitrailer, and dolly forward to pull the dolly out from under the rear semitrailer.

QUESTION NO: 15

After coupling twin trailers, charge the trailers by __________
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A. pushing in the “air supply” knob.
B. pulling out the “air supply” knob.
C. opening the air tank petcock.
D. closing the shut-off valves.

Answer: A Bottom of Form

Explanation:

To connect a converter dolly to the rear trailer when coupling twin trailers, first make sure the trailer brakes are locked and/or wheels are chocked. Make sure the trailer height is correct. (It must be slightly lower than the center of the fifth wheel, so the trailer is raised slightly when the dolly is pushed under.) Back the converter dolly under the rear trailer. Raise the landing gear slightly off the ground to prevent damage if the trailer moves.
Test the coupling by pulling against the pin of the second semitrailer. Make a visual check of the coupling. (There should be no space between the upper and lower fifth wheel. The locking jaws should be closed on the kingpin.) Connect the safety chains, air hoses, and light cords. Close the converter dolly air tank petcock and shut-off valves at the rear of the second trailer (service and emergency shut-offs). Open the shut-off valves at the rear of the first trailer (and on the dolly if so equipped). Raise the landing gear completely.
Charge the trailers (push the “air supply” knob in) and check for air at the rear of the second trailer by opening the emergency line shut-off. If air pressure isn’t there, something is wrong and the brakes won’t work.

QUESTION NO: 16

To test the trailer service brakes during the pre-trip inspection, __________
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A. charge the trailer air brake system, shut the engine off, and step on and off the brake pedal several times to reduce the air pressure in the tanks.
B. pull out the trailer air supply control and pull gently on the trailer with the tractor.
C. check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and use the trolley valve.
D. none of the above

Answer: C Bottom of Form

Explanation:

To test the trailer service brakes on a combination vehicle, check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply the trailer brakes with the hand control (trolley valve), if so equipped.
You should feel the brakes come on. This tells you that the trailer bakes are connected and working. (The trailer brakes should be tested with the hand valve, but controlled in normal operation with the foot pedal, which applies air to the service brakes at all wheels.)

QUESTION NO: 17

When you conduct your walkaround inspection during the Seven-step Inspection Method, make sure the shut-off valves in the service and emergency lines at the rear of the front trailers are __________ and at the rear of the last trailer are __________
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A. open, open.
B. open, closed.
C. closed, open.
D. closed, closed.

Answer: B Bottom of Form

Explanation:

When you conduct your walkaround inspection during step five of the Seven-step Inspection Method, check the shut-off valves (at rear of trailers, in service and emergency lines). At the rear of the front trailers, they should be open. At the rear of the last trailer, they should be closed. The converter dolly air tank drain valve should be closed.
Be sure air lines are supported and glad hands are properly connected. If the spare tire is carried on the converter gear (dolly), make sure it is secure. Be sure the pintle-eye of the dolly is in place in the pintle hook of the trailer(s). Make sure the pintle hook is latched. Safety chains should be secured to trailer(s). Be sure the light cords are firmly in sockets on trailers.

QUESTION NO: 18

When uncoupling the rear trailer of a double, apply the parking brakes so the rig won’t move, then __________
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A. close the air shut-offs at the rear of the first semitrailer (and on the dolly if so equipped).
B. lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
C. chock the wheels of the second trailer if it doesn’t have spring brakes.
D. none of the above

Answer: C
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Explanation:

To uncouple twin trailers, first uncouple the rear trailer. Park the rig in a straight line on firm, level ground. Apply the parking brakes so the rig won’t move. Chock the wheels of the second trailer if it doesn’t have spring brakes. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
Close the air shut-offs at the rear of the first semitrailer (and on the dolly if so equipped). Disconnect all dolly air and electric lines and secure them. Release the dolly brakes. Release the converter dolly fifth wheel latch. Slowly pull the tractor, first semitrailer, and dolly forward to pull the dolly out from under the rear semitrailer.

QUESTION NO: 19

To couple twin trailers, release the converter dolly brakes by opening the __________
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A. emergency line shut-off.
B. air tank petcock.
C. shut-off valves.
D. none of the above

Answer: B Bottom of Form

Explanation:

When coupling twin trailers, position the converter dolly in front of the second (rear) trailer. To do this, release the dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use the dolly parking brake control.) If the distance is not too great, wheel the dolly into position by hand so it is in line with the kingpin.
Or, use the tractor and first semitrailer to pick up the converter dolly: -Position combination as close as possible to converter dolly. -Move dolly to rear of first semitrailer and couple it to the trailer. -Lock pintle hook. -Secure dolly support in raised position. -Pull dolly into position as close as possible to nose of the second semitrailer. -Lower dolly support. -Unhook dolly from first trailer. -Wheel dolly into position in front of second trailer in line with the kingpin.

QUESTION NO: 20

When driving a double or triple in adverse conditions, you will have __________ than other drivers.
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A. less risk of skidding.
B. greater length to pull with your drive axles.
C. more dead axles to pull with your drive axles. .
D. both B and C

Answer: D Bottom of Form

Explanation:

When driving doubles or triples, be more careful in adverse conditions. In bad weather, slippery conditions, and mountain driving, you must be especially careful if you drive double and triple bottoms. You will have greater length and more dead axles to pull with your drive axles than other drivers. There is more chance for skids and loss of traction.

QUESTION NO: 21

To use a tractor and semitrailer combination to pick up a converter dolly, unhook the dolly from the first trailer, then __________
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A. wheel the dolly into position in front of the second trailer in line with the kingpin.
B. lower the dolly support.
C. secure the dolly support in the raised position.
D. none of the above

Answer: A Bottom of Form

Explanation:

To use the tractor and first semitrailer combination to pick up the converter dolly when coupling twin trailers, position the combination as close as possible to the converter dolly. Move the dolly to the rear of the first semitrailer and couple it to the trailer. Lock the pintle hook. Secure the dolly support in the raised position.
Pull the dolly into position as close as possible to the nose of the second semitrailer. Lower the dolly support. Unhook the dolly from the first trailer. Wheel the dolly into position in front of the second trailer in line with the kingpin.

QUESTION NO: 22

If the __________ doesn’t work correctly, the emergency brakes could come on and cause you to lose control of your vehicle.
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A. tractor protection valve
B. tractor parking brake
C. trailer air supply control
D. both A and C

Answer: D Bottom of Form

Explanation:

During your pre-trip inspection on a combination vehicle, test the tractor protection valve. Charge the trailer air brake system. (that is, build up normal air pressure and push the “air supply” knob in). Shut the engine off. Step on and off the brake pedal several times to reduce the air pressure in the tanks.
The trailer air supply control (also called the tractor protection valve control) should pop out (or go from “normal” to “emergency” position) when the air pressure falls into the pressure range specified by the manufacturer. (Usually within the range of 20 to 45 psi). If the tractor protection valve doesn’t work properly, an air hose or trailer brake leak could drain all the air from the tractor. This would cause the emergency brakes to come on, with possible loss of control.

QUESTION NO: 23

When uncoupling the rear trailer of a double, which of the following should be done first?
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A. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
B. Release the dolly brakes.
C. Disconnect all dolly air and electric lines and secure them.
D. Release the converter dolly fifth wheel latch.

Answer: A Bottom of Form

Explanation:

To uncouple twin trailers, first uncouple the rear trailer. Park the rig in a straight line on firm, level ground. Apply the parking brakes so the rig won’t move. Chock the wheels of the second trailer if it doesn’t have spring brakes. Lower the landing gear of the second semitrailer enough to remove some weight from the dolly.
Close the air shut-offs at the rear of the first semitrailer (and on the dolly if so equipped). Disconnect all dolly air and electric lines and secure them. Release the dolly brakes. Release the converter dolly fifth wheel latch.
Slowly pull the tractor, first semitrailer, and dolly forward to pull the dolly out from under the rear semitrailer.

QUESTION NO: 24

To connect a converter dolly to the front trailer when coupling twin trailers, hook the dolly to the front trailer, then __________
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A. lock the pintle hook.
B. secure the converter gear support in the lowered position.
C. both A and B
D. neither A nor B

Answer: A Bottom of Form

Explanation:

To connect a converter dolly to the front trailer when coupling twin trailers, back the first semitrailer into position in front of the dolly tongue. Hook the dolly to the front trailer by locking the pintle hook and securing the converter gear support in the raised position.

QUESTION NO: 25

When driving a double or triple, __________
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A. be sure you are clear at the sides before changing lanes.
B. allow less following distance.
C. realize that your vehicle will be easy to stop suddenly.
D. all of the above

Answer: A Bottom of Form

Explanation:

Doubles and triples must be driven very smoothly to avoid rollover or jackknife. Therefore, look far ahead so you can slow down or change lanes gradually when necessary. Doubles and triples take up more space than other commercial vehicles.
They are not only longer, but also need more space because they can’t be turned or stopped suddenly. Allow more following distance. Make sure you have large enough gaps before entering or crossing traffic. Be certain you are clear at the sides before changing lanes.