Texas CDL Questions And Answers
v. 1.0a

by Jay Banks



Section 2

Section 3

Section 4
Section 5
Section 6
Section 7
Section 8
Section 9


These are the questions and answers to the Texas Commercial Motor Vehicle Drivers Handbook, labeled as last revised January, 2002. As per this Handbook, these questions may be on the CDL test. If you can't answer them all, re-read the section in question until you can.

While every effort was made to be as accurate as possible on the answers, the author of this document assumes no liability on his part as per its accuracy. As of this writing, several questions were left unanswered. As the document is updated, the document version number will be updated. Check back to this web site from time to time to make sure you have the latest version number.

Good luck on your test! 

Section 2: Driving Safely

1. What is the most important reason for doing a vehicle inspection?

Safety is the most important reason you inspect your vehicle. Safety for yourself and for other road users. (page 2-1)

2. What things should you check during a trip?

Watch gauges for signs of trouble.

-Tires, wheels and rims.
-Lights and reflectors.
-Brake and electrical connections to trailer.
-Trailer coupling devices.
-Cargo securement devices. (page 2-1)

3. Name some key steering system parts.

Steering wheel, steering gear box, tie rod, spindle, drag link, steering ring knuckle, steering arm. Steering wheel shaft. (page 2-2)

4. Name some suspension system defects.

5. What three kinds of emergency equipment must you have?

6. What is the minimum tread depth for front tires?

You need at least 4/32 inch tread depth in every major groove on front tires. No fabric should show through the tread or sidewall. (page 2-1)

7. For other tires?

You need 2/32 inch on other tires. No fabric should show through the tread or sidewall. (page 2-1).

8. Name some things you should check on the front of your vehicle during the walk-around inspection.

 - No loose, worn, bent, or damaged or missing parts.
 - Must grab steering mechanism to test for looseness.

 -Check for damage and clean if dirty.
 -Check windshield wiper arms for proper spring tension.
 -Check wiper blades for damage, "stiff" rubber, and securement.

 -Parking, clearance, and identification lights clean, operating, and proper color (amber at front).
 -Right front turn signal light clean, operating, and proper color (amber or white on signals facing forward). (page 2-7)

9. What should wheel bearing seals be checked for?

That they are not leaking. (page 2-8)

10. How many red reflective triangles should you carry?

Three. (page 2-6)

11. How do you test hydraulic brakes for leaks?

Pump the brake pedal three times. Then apply firm pressure to the pedal and hold for five seconds. The pedal should not move. If it does, there may be a leak or other problem. Get it fixed before driving. (pages 2-8 thru 2-9)

12. Can you bring the "vehicle inspection memory aide" with you to the test?


13. Why put the starter switch key in your pocket during the pre-trip inspection?

Always put the key in your pocket because someone might move the vehicle while you are checking underneath it.

14. Why should you back toward the driver's side?

Back toward the driver's side so you can see better. If you back and turn toward the driver's side, you can watch the rear of your vehicle by looking out the side window. Use driver's side backing even if it means going around the block to put your vehicle in this position. The added safety is worth it. (page 2-10).

15. What is a pull-up?

Pulling your vehicle forward when backing a trailer in order to reposition it as needed. (page 2-10)

16. If stopped on a hill, how can you start moving without rolling back?

By partly engaging the clutch before you take your right foot off the brake. You can also engage the parking brake. If you do so, only release the parking brake when you have applied enough engine power to keep from rolling back. On a tractor-trailer equipped with a trailer brake hand valve, the hand valve can be applied to keep from rolling back. (page 2-10)

17. When backing, why is it important to use a helper?

Because there are spot you can't see. (page 2-10)

18. What's the most important hand signal that you and the helper should agree on?

Agree on a signal for "stop." (page 2-10)

19. What are the two special condition where you should downshift?

Before starting down a hill and before entering a curve. (page 2-11)

20. When should you downshift automatic transmissions?

You can select a low range to get greater engine braking when going down grades. (page 2-11)

21. Retarders keep you from skidding when the road is slippery. True or False?

False. Retarders help slow a vehicle, reducing the need for using your brakes. When your drive wheels have poor traction, the retarder may cause them to skid. Therefore, you should turn the retarder off whenever the road is wet, icy, or snow covered. (pages 2-11 thru 2-12)

22. What are the two ways to know when to shift?

Use engine speed. Watch your tachometer, and shift up when your engine reaches the top of the range for your engine.

Use road speed. Learn what speeds each gear is good for. Then by using the speedometer, you'll know when to shift up.

23. How far ahead does the manual say you should look?

12 to 15 seconds ahead, which means the distance you would travel in 12 to 15 seconds. At slower speeds, that's about a block. At highway speeds it's about a quarter of a mile. (page 2-12)

24. What are two main things to look for ahead?

Look for traffic: Vehicles coming onto the highway, into our lane, or turning. Watch for break lights from slowing vehicles.

Look for road conditions. Look for hills and curves anything you'll have to slow or change lanes for. Pay attention to traffic signals and signs. Watch for stale green lights that may change before you get there. (page 2-12)

25. What does "communicating" mean in safe driving?

Signaling what you intend to do. (page 2-13)

26. Where should your reflectors be placed when stopped on a divided highway?

10 feet, 100 feet, and 200 feet toward the approaching traffic. (page 2-14)

27. What three things add up to total stopping distance?

   Perception Distance
+ Reaction Distance
+ Braking Distance
= Total stopping distance. (page 2-15)

28. If you go twice as fast, will your stopping distance increase by twice or four times?

Whenever you double your speed, it takes about four time as much distance to stop and your vehicle has about four times the destructive power if it crashes. (page 2-15)

29. Empty trucks have the best braking. True or False?

False. Empty trucks require greater stopping distances, because an empty vehicle has less traction. It can bounce and lock up its wheels, giving much poorer braking. (page 2-15)

30. What is hydroplaning?

Hydroplaning which is comparable to your tires water skiing happens when the tires lose their contact with the road and have little or no traction. You can regain control by releasing the accelerator and pushing in the clutch. (page 2-15)

31. What is "black ice?"

Black ice is a thin layer of ice that is clear enough that you can see the road under it. It makes the road look wet. Any time the temperature is below freezing and the road looks wet, watch out for black ice. (page 2-15)

32. How do you find out how many seconds of following distance space you have?

To know how much space you have, wait until the vehicle ahead passes a shadow on the road, a pavement marking, or some other clear landmark. Then count off the seconds like this "one thousand-and-one, one thousand-and-two" and so on, until you reach the same spot. Keep at least four seconds for 40-foot truck and five seconds if you are going over 40 mph. (page 2-17)

33. If you are driving a 30-foot vehicle at 55 mph, how many seconds of following distance should you allow?

You should allow at least 4 seconds: one second for for each 10 feet of vehicle length at speeds under 40 mph, plus one second for safety when exceeding 40 mph. (page 2-17)

34. You should decrease your following distance if somebody is following you too closely. True or False?

False. Increase your following distance. Opening up room in front of you will help you to avoid having to make sudden speed or direction changes. It also makes it easier for the tailgater to get around you. (page 2-17)

35. If you swing wide to the left before turning right, another driver may try to pass you on the right. True or false?

True. (page 2-18)

36.You should use low beams whenever you can. True or False?

False. Some drivers make the mistake of always using low beams. This seriously cuts down on their ability to see ahead. Use high beams when it is safe and legal to do so.  use them when you are not within 500 feet of an approaching vehicle. (page 2-20).

37. What should you do before you drive if you are drowsy?

Get some sleep. If you are sleepy, the only safe cure is to get off the road and get some sleep. (page 2-19)

38. What effects can wet brakes cause? How can you avoid these problems?

Water in the brakes can cause brakes to be weak, to apply unevenly, or to grab. Avoid driving through deep puddles or flowing water if possible. if not, you should:

39. you should let air out of hot tires so the pressure goes back to normal. True or False?

False. Do not let air out or the pressure will be too low when the tires cool off. If a tire is too hot to touch, remain stopped until the tire cools off. Otherwise the tire may blow out or catch fire. (page 2-22)

40. You can safely remove the radiator cap as long as the engine isn't overheated. True or False?

False. Never remove the radiator cap or any part of the pressurized system until the system has cooled. If you can touch the radiator cap with your bare hand, it is probably cool enough to open.

41. What factors determine your selection of a "safe" speed when going down a long, steep downgrade?

42. Why should you be in the proper gear before starting down a hill?

Do not try to downshift after your speed has already built up due to the hill. You will not be able to shift into a lower gear. You may not even be able to get back into any gear and all engine braking effect will be lost. Forcing an automatic transmission into a lower gear at high speed could damage the transmission and also lead to loss of all engine braking effect. (page 2-24).

43. Describe the proper braking technique when going down a long, steep downgrade.

1. Apply the brakes just hard enough to feel a definite slowdown.

2. When your speed has been reduced to approximately five mph below your "safe" speed, release the brakes. [This brake application should last for about three seconds.]

3. When your speed has increased to your "safe" speed, repeat steps 1 and 2. (page 2-24)

44. What is a hazard?

A hazard is any road condition or other road user (driver, bicyclist, pedestrian) that is a possible danger. (page 2-24)

45. Why make emergency plans when you see a hazard?

So that you are always prepared to take action based on your plans. In this way you will be a prepared defensive driver who will improve not only your own safety but the safety of all road users. (page 2-26)

46. Stopping is not always the safest thing to do in an emergency. True or False?

True. Stopping is not always the safest thing to do in an emergency. When you don't have enough room to stop, you may have to steer away from what's ahead. Remember, you can almost always turn to miss an obstacle more quickly than you can stop. However, top-heavy vehicles and tractors with multiple trailers may flip over. (page 2-27)

47. What are some advantages of going right instead of left around an obstacle?

If the shoulder is clear, going right may be best. No one is likely to be driving on the shoulder but someone may be passing you on the left. You will know if you have been using your mirrors. Also, if you are blocked on both sides, a move to the right may be best. At least you won't force anyone into an opposing traffic lane and a possible head-on collision. (page 2-27)

48. What is an "escape ramp?"

Off ramps built on steep downgrades that use soft gravel that resists the motion of the vehicle and brings it to a stop, or an off ramp that turns uphill, using the hill to stop the vehicle and soft gravel to hold it in place. (page 2-28)

49. If a tire blows out, you should put the brakes on hard to stop quickly. True or False?

False. Unless you're about to run into something, stay off the brake until the vehicle has slowed down. Then brake very gently, pull off the road and stop. (page 2-29).

50. What are some things to do at an accident scene to prevent another accident?

51. Name two causes of tire fires.

Tires that are under-inflated or duals that touch. (page 2-30)

52. What kinds of fires is a B:C extinguisher not good for?

Burning wood, paper and cloth. (page 2-31)

53. When using your extinguisher, should you get as close as possible to the fire?

No. Stay as far away from the fire as possible.  (page 2-31)

54. Name some causes of vehicle fires.

Spilled fuel after an accident, improper use of flares. Electrical system shorts due to damaged insulation or loose connections. Driver smoking while fueling, improper fueling, and loose fuel connections. Cargo that is flammable, improperly sealed or loaded, and poor ventilation of cargo. (page 2-30)

55. Common medicines for colds can make you sleepy. True or False.

True. Many medications can make you sleepy. The most common medicine of this type is an ordinary cold pill. If you have to drive with a cold, you are better off suffering from the cold than from the effects of the medicine. (page 2-32)

56. What should you do if you do become sleepy while driving?

Stop to sleep. When your body needs sleep, sleep is the only thing that will work. Take a nap. If you can't stop for the night, at least pull off at a safe place, such as a rest area or truck stop, and take a nap. A nap as short as a half-hour will do more to overcome fatigue than a half-hour coffee stop. (Page 2-32)

57. Coffee and a little fresh air will help a drinker sober up. True or False

False. Only time will help a drinker sober up other methods just don't work. (page 2-32)

58. What is a hazardous material placard?

Placards are signs put on the outside of a vehicle which identify the hazard class of the cargo. (Page 2-34)

59. Why are placards used?

Placards are used to warn others of hazardous materials. (page 2-34)


Section 3: Transporting Cargo Safely


1. For what three things related to cargo and drivers responsible?

2. How often must you stop while on the road to check your cargo?

Every three hours or 150 miles.

3. How is Gross Combination Weight Rating different from Gross Combination Weight?

The Gross Vehicle Weight Rating (GCWR) is the maximum Gross Combination Weight (GCW) specified by the manufacturer, while the Gross Combination Weight (GCW is the actual weight of a powered unit plus trailers plus the cargo. (page 3-1)

4. Name two situation where legal maximum weights may not be safe?

During bad weather or in mountains.  (page 3-2)

5. What can happen if you don't have enough weight on the front axle?

Underloaded front axles, caused by shifting weight too far to the rear, can make the steering axle weight too light to steer safely. (page 3-2)

6. What is the minimum number of tiedowns for any flatbed load?

No matter how small the cargo, it should have at least two tiedowns holding it. (page 3-2)

7. What is the minimum number of tiedowns for a 20 ft. load?

Two. Cargo should have at least one tiedown for each 10 feet of cargo.

8. Name the two basic reasons for covering cargo on an open bed.

1) To protect people from spilled cargo, and 2) to protect the cargo from weather. (page 3-3)

9. What must you check before transporting a sealed load?

That you don't exceed gross weight and axle weight limits. (page 3-3)


Part Two

Section 4: Transporting Passengers

1. Name some things to check in the interior of a bus during a pre-trip inspection.

Each handhold and railing. Floor covering. Signaling devices, including the restroom emergency buzzer, if the bus has a restroom. And emergency exit handles. (Page 4-1)

2. What are some hazardous materials you can transport by bus?

Buses may carry small-arms ammunition labeled ORM-D, emergency hospital supplies, and drugs. (Page 4-2)

3. What are some hazardous materials you can't transport by bus?

4. What is a standee line?

A 2-inch line on the floor of the bus, or some other means, showing riders where they cannot stand. All standing riders must stay behind this line. No rider may stand forward of the rear of the driver's seat. (page 4-2)

5. Does it matter where you make a disruptive passenger get off the bus?

Yes, Don't discharge such riders where it would be unsafe for them. It may be safer at the next scheduled stop or a well-lighted area where there are other people. Many carriers have guidelines for handling disruptive riders. (page 4-3)

6. How far from a railroad crossing should you stop?

Between 15 and 50 feet before railroad crossings. Listen and look in both directions for trains. You should open your forward door if it improves your ability to see or hear an approaching train. Before crossing after a train has passed, make sure there isn't another train coming in the other direction on other tracks. If your bus has a manual transmission, never change gears while crossing the tracks. (page 4-3)

7. When must you stop before crossing a drawbridge?

When there is no signal light or traffic control attendant. Stop at least 50 feet before the draw of the bridge. Look to make sure the draw is completely closed before crossing. (Page 4-3)

8. Describe from memory the "prohibited practices" listed above.

Avoid fueling your bus with riders on board unless absolutely necessary. Never refuel in a closed building with riders on board.

Don't talk with riders, or engage in any other distracting activity, while driving.

Do not tow or push a disabled bus with riders aboard the vehicle, unless getting off would be unsafe. Only tow or push the bus to the nearest safe spot to discharge passengers. Follow your employer's guidelines on towing or pushing disabled buses. (page 4-4)

9. The rear door of a transit bus has to be open to put on the parking brake. True or False?

False. The rear door must be open to engage the brake and accelerator interlock system not the parking brake. The rear door closing releases these interlock systems not the parking brake. Do not use the brake-door interlocks in place of the parking brake. (page 4-4)


Section 5: Air Brakes

1. Why must air brakes be drained?

To drain the water and compressor oil that collects in the bottom of the air tank. These substances are bad for the brake system because they could freeze in cold weather. (page 5-1)

2. What is a supply pressure gauge used for?

These gauges tell you how much pressure is in the air tanks. All air-braked vehicles have a pressure gauge connected to the air tank. If the vehicle has a dual air brake system, there will either be a gauge for each half of the system or a single gauge with two needles. (page 5-2)

3. All vehicles with air brakes must have a low air pressure warning signal. True or False?

True. A low pressure warning signal is required on vehicles with air brakes. A warning signal you can see must come on before the air pressure in the tanks falls below 60 psi. (Or one half the compressor governor cutout pressure on older vehicles.) The warning is usually a red light. A buzzer may also come on. (page 5-3)

4. What are spring brakes?

They are emergency brakes and parking brakes that are held on by mechanical force because to if air was used, the air pressure could eventually leak away. These brakes are applied when either the driver engages the parking break control in the cab or if there is a leak in the air brake system. Tractor and straight truck spring brakes will come fully on when the air pressure drops to a range of 20 - 45 psi (typically 20 to 30 psi). (page 5-3)

5. Front wheel brakes are good under all conditions. True or False?

True. Tests have shown front wheel skids from braking are not likely even on ice. (Page 5-3)

6. What is a dual air brake system?

A dual air brake system has two separate air brake systems which use a single set of brake controls. Each system has its own air tanks, hoses, lines, etc. One system typically operates the regular brakes on the rear axle or axles. The other system operates the regular brakes on the front axle (and possibly one rear axle). Both systems supply air to the trailer (if there is one). The first system is called the "primary" system. The other is called the "secondary" system. (page 5-4)

7. What are the slack adjusters?


8. How can you check slack adjusters?

Park on level ground and chock the wheels to prevent the vehicle from moving. Turn off the parking brakes so you can move the slack adjusters. Use gloves and pull hard on each slack adjuster that you can get to. If a slack adjuster moves more than about one inch where the push rod attaches to it, it probably needs adjustment. Adjust it or have it adjusted. Vehicles with too much brake slack can be very hard to stop. Out-of-adjustment brakes are the most common problem found in roadside inspection. Be safe. Check the slack adjusters. (page 5-4)

9. How can you test the low pressure warning signal?

Shut the engine off when you have enough air pressure so that the low pressure warning signal is no on. Turn the electrical power on and step on and off the brake pedal to reduce air tank pressure. The low air pressure warning signal must come on before the pressure drops to less than 60 psi in the air tank (or tank with the lowest air pressure, in dual air systems).

If the warning signal doesn't work, you could lose air pressure and you would not know it. (page 5-5)

10. How can you check to see that the spring brakes come on automatically?

Choc the wheels, release the parking brakes when you have enough air pressure to do it, and shut the engine off. Step on and off the brake pedal to reduce the air tank pressure. The "parking brake" knob should pop out when the air pressure falls to the manufacture's specification (usually in a range between 20 - 40 psi). This causes the spring brakes to come on. (page 5-5)

11. What are the maximum leakage rates?

With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop.  The loss rate should be less than two psi in one minute for single vehicles and less than three psi in one minute for combination vehicles. Then apply 90 psi or more with the brake pedal. After the initial pressure drop, if the air pressure falls more than three psi in one minute for single vehicles or more than four psi for combination vehicles, the air loss rate is too much. Check for air leaks and fix before driving the vehicle. Otherwise, you could lose your brakes while driving. (page 5-4)

12. Why should you be in the proper gear before starting down a hill?

Brakes can fade or fail from excessive heat caused by using them too much and not relying on the engine braking effect. (page 5-6)

13. What factors can cause brakes to fade or fail?

Brakes can fade or fail from excessive heat caused by using them too much and not relying on the engine braking effect. Brake fade results from excessive heat causing chemical changes in the brake lining which reduce friction and also causes expansion of the brake drums. As the overheated drums expand, the brake shoes and linings have to move farther to contact the drums, and the force of this contact is also reduced. Continued overuse may increase brake fade until the vehicle cannot be slowed down or stopped at all. (page 5-6)

14. The use of brakes on a long steep downgrade is only a supplement to the braking effect of the engine. True or False?

True. (page 5-6)

15. If you are away from your vehicle only a short time, you don't need to use the parking brake. True or False?

False. Never leave your vehicle unattended without applying the parking brakes or chocking the wheels. Your vehicle might roll away and cause injury and damage. (page 5-7)

16. How often should you drain air tanks?

If your vehicle does not have automatic air tank drains, drain your air tanks at the end of each working day to remove moisture and oil. Otherwise the brakes could fail. (page 5-7)


Section 6: Combination Vehicles


1. What two thing are important to prevent rollover?

Keep the cargo as close to the ground as possible, and drive slowly around turns. (page 6-1)

2. When you turn suddenly while pulling doubles, which trailer is most likely to turn over?

The last trailer. (page 6-1)

3. Why should you not use the trailer hand brake to straighten out a jackknifing trailer?

This is the wrong thing to do since the brakes on the trailer wheels caused the skid in the place. (page 6-2)

4. What is offtracking?

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels. (page 6-2)

5. Why should you turn like it shows in Figure 6-5?

Do this so cars don't try to pass you on the right. (page 6-3)

6. Why should you not use the trailer hand valve while driving?

The trailer hand valve should be used only to test the trailer brakes. Do not use it in driving because of the danger of making the trailer skid. The foot brake sends air to all of the brakes on the vehicle (including the trailer[s]). There is much less danger of causing a skid or jackknife when using just the foot brake. (page 6-3)

7. Describe what the trailer air supply control does.

The trailer air supply control on newer vehicles is a red eight-sided know which you use to control the tractor protection valve. You push it in to supply the trailer with air, and pull it out to shut the air off and put on the trailer emergency brakes. The valve will pop out (thus closing the tractor protection valve) when the air pressure drops into the range of 20 - 45 psi. Tractor protection valve controls or "emergency" valves on older vehicles may not operate automatically. There may be a lever rather than a knob. The "normal" position is used for pulling a trailer. The "emergency" position is used to shut the air off and put on the trailer emergency brakes. (page 6-4)

8. Describe what the service line is for.

The service line (also called the control line or signal line) carries air which is controlled by the foot brake or the trailer hand brake. Depending on how hard you press the foot brake or hand valve, the pressure in the service line will similarly change. The service line is connected to relay valves. These valves allow the trailer brakes to be applied more quickly than would otherwise be possible. (page 6-4)

9. What is the emergency air line for?

The emergency line (also called the supply line) has two purposes. First, it supplies air to the emergency trailer air tanks. Second, the emergency line controls the emergency brakes on combination vehicles. Loss of air pressure in the emergency line causes the trailer emergency brakes to come on. The pressure loss could be caused by a trailer breaking loose, thus tearing apart the emergency air hose. Or it could be caused by a hose, metal tubing, or other part which breaks, letting the air out. When the emergency line loses pressure, it also caused the tractor protection valve to close (the air supply know will pop out). (page 6-4)

10. Why should you use chocks when parking a trailer without spring brakes?

Those that do not have spring brakes have emergency brakes which work from the air stored in the trailer air tank. The emergency brakes come on whenever air pressure in the emergency line is lost. These trailers have no parking brake. The emergency brakes come on whenever the air supply knob is pulled out or the trailer is disconnected. But the brakes will hold only as long as there is air pressure in the trailer air tank. Eventually, the air will leak away and then there will be no brakes. Therefore, it is very important for safety that you use wheel chocks when you park trailers without spring brakes. (page 6-5)

11. Where are the shut-off valves?

Shut-off valves (also called cut-out cocks) are used in the service and supply air lines at the back of trailers used to tow other trailers. These valves permit closing the air lines off when another trailer is not being towed. You must check that all shut-off valves are in the open position except the ones at the back of the last trailer, which must be closed. (page 6-4)

12. What might happen if the trailer is too high when you try to couple?

If the trailer is too high, it may not couple correctly. (page 6-5)

13. After coupling, how much space should be between the upper and lower fifth wheel?

Make sure there is no space between the upper and lower fifth wheel. If there is space, something is wrong (kingpin may be on top of closed fifth wheel jaws; trailer would come loose very easy). Page 6-6)

14. You should look into the back of the fifth wheel to see if it is locked onto a kingpin. True of False?

True. Go under the trailer and look into the back of the fifth wheel. Make sure the fifth wheel jaws have closed around the shank of the kingpin (see figure 6-7). (page 6-6)

15. To drive you need to raise the landing gear only until it just lifts off the pavement. True or False?

False. Raise the landing gear all the way up. Never drive with landing gear only part way up, as it may catch on railroad tracks or other things. (page 6-7)

16. What is a converter dolly?


17. Which shut-off valve should be open and which closed?

All shut-off valves should be in open position except the ones at the back of the last trailer, which must be closed. (page 6-4)

18. How can you test that air flows to all trailers?

Use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for 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), 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(s) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work. (pages 6-8 - 6-9)

19. How can you 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). (page 6-9)

20. How can you test the trailer emergency brakes?

Charge the trailer air brake system and check that the trailer rolls freely. Then stop and pull out the trailer air supply control (also called tractor protection valve control) or trailer emergency valve or place it in the "emergency" position. Pull gently on the trailer with the tractor to check that the trailer emergency brakes are on. (page 6-9)

21. How can you test the trailer service brakes?

Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and apply trailer brakes with the hand control trolley valve, if so equipped. You should feel the brakes come on. This tells you the trailer brakes 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. (page 6-9)


Section 7: Doubles and Triples


1. What is a converter dolly?

A converter dolly, or gear, is a coupling device of one or two axles and a fifth wheel by which a semitrailer can be coupled to the rear of a tractor-trailer combination forming a double bottom rig. (page 7-1)

2. Do converter dollies have spring brakes?

Converter dollies have air brakes but may have spring brakes: Release dolly brakes by opening the air tank petcock (or if the dolly has spring brakes, use the dolly parking brake control (page 7-2)

3. What three methods can you use to secure a second trailer before coupling?

Set the second trailer's spring brakes, if it has them. Or, drive the tractor close to the trailer and connect the emergency line, charging the air tank; this will set the trailer emergency brakes (if the slack adjusters are correctly adjusted). Or thirdly, chock the wheels if you have any doubt about the brakes (page 7-1)

4. How do you check to make sure trailer height is correct before coupling?

It must be slightly lower than the center of the fifth wheel, so trailer is raised slightly when dolly is pushed under. (page 7-2)

5. What do you check when making a visual check of coupling?

Make sure there is no space between the upper and lower fifth wheel and that the locking jaws are closed on the kingpin (page 7-2)

6. Why should you pull a dolly out from under a trailer before you disconnect it from the trailer in front?

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. (page 7-2)

7. What should you check for when inspecting the converter dolly? The pintle hook?

Make sure the pintle eye of dolly is in place in pintle hook of trailers. Make sure the pintle hook is latched. (page 7-3)

8. Should the shut-off valves on the rear of the last trailer be open or closed? On the first trailer in a set of doubles? On the middle trailer of a set of triples?

Air should flow through all trailers until the last one for the brakes to work, so on the last trailer it should be closed. On a first trailer in a set of doubles it should be open. On a middle trailer of a set of triples, it should be open. (page 7-4)

9. How can you test that air flows to all trailers?

Use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for air pressure to reach normal, then push in the red "trailer air supply" knob. Use the trailer hand brake to provide air to the service line. Go to the rear of the rig. Pen 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 hand brake or the service brake pedal is on, then close the valve). If you do NOT hear air escaping from both lines, check that the shut-off valves on the trailers and dolly(s) are in the OPEN position. You MUST have air all the way to the back for all the brakes to work. (page 7-4)


Section 8: Tank Vehicles

1. How are bulkheads different than baffles?

Tanks with bulkheads are tanks that are divided into several smaller tanks (when loading and unloading the smaller tanks, the liquid should be divided evenly between the tanks in order to distribute the weight on the trailer).

Tanks with baffles are tanks that have bulkheads with holes in them that let the water flow through, which helps to control the forward and backward liquid surge (side to side surge can still occur and this could result in rollover). (page 8-2)

2. Should a tank vehicle take curves, onramps, or offramps at the posted speed limits?

No, the posted speeds may be too fast for a tank vehicle.

3. How are smooth bore tankers different to drive than those with baffles?

Forward-and-back surge is very strong in un-baffled or "smooth bore" tanks. Be extremely cautious slow and careful in driving smooth bore tanks, especially when starting and stopping. (page 8-2)

4. What three things determine how much liquid you can load?

The amount the liquid will expand, the weight of the liquid, and he legal weight limits. (page 8-2)

5. What is outage?

Never load a cargo tank totally full. Liquids expand as they warm and you must leave room for the expanding liquid. This is called "outage." Since different liquids expand by different amounts, they require different amounts of outage. You must know the outage requirement when hauling liquids in bulk. (page 8-2)

6. What two reasons make special care necessary when driving tank vehicles?

A high center of gravity, which makes the load's weight high up off the road, making the vehicle top-heavy and easy to roll over. And the danger of surge, resulting from the movement of the liquid in partially filled tanks. (page 8-1)


Section 9: Hazardous Materials


1. Shippers package in order to _______ the material.


2. Drivers placard their vehicle to ___________ the risk.

"communicate" (page 9-1)

3. What three things do you need to know to decide which placards if any you need?

You can decide which placards to use if you know these three things:

4. A hazardous materials identification number must appear on the _______________ and on _________________. The identification number must also appear on cargo tanks and other bulk packaging.

"shipping paper as part of the shipping description" and "on the package." (page 9-4)

5. where must you keep shipping papers describing hazardous materials?

-In a pouch on the driver's door, or
-In clear view within immediate reach while the seat belt is fastened while driving, or
-On the driver's seat when out of the vehicle. (page 9-3)

6. What is a shipper's certification? Where does it appear? Who signs it?

On the original shipping paper. It is signed by the shipper to certify that the package has been prepared according to the rules. (page 9-7)

7. Name five hazard classes that require placarding in any amount.

1.1 Explosives 1.1
1.2 Explosives 1.2
1.3 Explosives 1.3
2.3 Poison Gas
4.3 Dangerous when wet (page 9-8)

8. A shipment described on the Hazardous Waste Manifest may only be delivered to another ____________ carrier or treatment facility, which then signs the ________________ giving you a copy which you must keep.

"registered" and "manifest" (page 9-8)

9. Your load includes 20 pounds of Division 2.3 gas and 1,001 pounds of flammable gas. What placards do you need, if any?

You need a placard for the Division 2.3 gas in any amount and a Division 3 placard because it meets the 1,001 pounds or more requirement. (page 9-8)

10. Around which hazard classed must you never smoke?

Class 1 (explosives), Division 2.1 (Flammable Gas), Class 5 (oxidizers), Class 4 (flammable solids), Class 3 (flammable liquids). (page 9-9)

11. Which three hazard classes should not be loaded into a trailer that has a heater/air condition unit?

Class 1 (explosives), Class 3 (flammable liquids), and Division 2.1 (flammable gas). (page 9-10)

12. Should the floor liner required for Division 1.1 or 1.2 Explosives A be stainless steel?

No. Use a floor lining with Division 1.1, 1.2, or 1.3 Class A or B explosives. The floors must be tight and the liner must be either non-metallic material or non-ferrous metal. (page 9-10)

13. At the shipper's dock you're given a paper for 100 cartons of battery acid. You already have 100 pounds of dry Silver Cyanide on board. What precautions do you have to take?

Do not load Division 6.1 (cyanides or cyanide mixtures) in the same vehicle with acids, corrosive materials, or other acidic materials which could release hydorcyanic acid from cyanides. (page 9-11)

14. Name a hazard class that uses transport indexes to determine the amount that can be loaded in a single vehicle.

Class 7 radioactive materials. (page 9-11)

15. What are cargo tanks?

Cargo tanks are bulk packagings permanently attached to a vehicle. (page 9-12)

16. How is a portable tank different from a cargo tank?

They are not permanently attached to a vehicle. (page 9-12).

17. Your engine runs a pump used during delivery of compressed gas. Should you turn off the engine before or after unhooking hoses after delivery?

If you must use the engine, turn it off after product transfer, before you unhook the hose. (page 9-12)

18. If your placarded trailer has dual tires, how often should you check the tires?

Check B placarded vehicles with dual tires at the start of each trip and when you park. You must stop and check the tires every 2 hours or 100 miles, whichever is less. (page 9-14)

19. What is a safe haven?

A safe haven is an approved place for parking unattended vehicles loaded with explosives. (page 9-13)

20. How close to the traveled part of the roadway can you park with Division 1.2 or 1.3 Explosive B?

Never park with Division 1.1, 1.2, or 1.3 Class A or B explosives within five feet of the traveled part of the road. Except for short periods of time needed for vehicle operation necessities (e.g. fueling). (page 9-13)

21. How close can you park to a bridge, tunnel, or building with the same load?

Do no park within 300 feet of a bridge, tunnel, or building. (page 9-13)

22. What type of fire extinguisher must placarded vehicles carry?

The vehicle must have a fire extinguisher with a UL rating of 10 B-C or more. (page 9-14)

23. You're hauling 100 pounds of Division 4.3 (dangerous when wet ) material. Do you need to stop before railroad crossings?

Yes. (page 9-14)

24. At a rest area you discover your hazardous materials shipment is slowly leaking from the vehicle. There's no phone around. What should you do?

Never continue driving with hazardous material leaking from you vehicle in order to find a phone booth, truck stop, help, or similar reason. If hazardous materials are spilling from you vehicle:

25. What is the Emergency Response Guide (ERG)?

A Department of Transportation guidebook for firefighters, police, and industry workers on how to protect themselves and the public from hazardous materials. (page 9-15)



This document released under the

Attribution-NonCommercial-ShareAlike 2.0

You are free:

  • to copy, distribute, display, and perform the work

  • to make derivative works

Under the following conditions:

Attribution. You must give the original author credit.
Noncommercial. You may not use this work for commercial purposes.
Share Alike. If you alter, transform, or build upon this work, you may distribute the resulting work only under a license identical to this one.
  • For any reuse or distribution, you must make clear to others the license terms of this work.

  • Any of these conditions can be waived if you get permission from the copyright holder.

Your fair use and other rights are in no way affected by the above.

This is a human-readable summary of the Legal Code (the full license).