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CDL Training > CDL QUIZ Air Brakes > Flashcards

CDL QUIZ Air Brakes Flashcards

1
Q
  1. Do converter dollies have spring brakes?
A

Yes

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2
Q
  1. What is the emergency air-line for?
A

1 supplies air to the trailer air tanks; 2 controls the emergency brakes on combination vehicles.

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3
Q

What are the maximum leakage rates?

A

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

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4
Q
  1. What might happen if the trailer is too high when you try to couple?
A

if the trailer is too high, it may not couple correctly

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5
Q
  1. Where are shut-off valves?
A

at the back of trailers used to tow other trailers

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

the dolly tow bar may fly up and possibly cause injury and making it quite difficult to recouple

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7
Q

Why must air tanks be drained?

A

Compressed air usually has some water and some compressor oil in it, which is bad for the air brake system

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8
Q
  1. Why should you not use the trailer hand valve while driving?
A

danger of making the trailer skid.

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9
Q

What are spring brakes?

A

held on by mechanical force

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10
Q

How can you test the low pressure warning signal?

A

Shut the engine off when you have enough air pressure Turn the electrical power on and step on and off the brake pedal; warning signal must come on before the pressure drops to less than 60 psi (or tank with the lowest air pressure, in dual air systems)

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11
Q

How often should you drain air tanks?

A

at the end of each day of driving

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12
Q
  1. What do you check when making a visual check of coupling?
A

Make sure there is no space between upper and lower 5th wheel and that the locking jaws are locked on the kingpin

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13
Q

How do you know if your vehicle is equipped with antilock brakes?

A

Tractors, trucks, and buses will have yellow ABS malfunction lamps on the instrument panel

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14
Q

How can you check that the spring brakes come on automatically?

A

stepping on and off the brake pedal to reduce tank pressure. The tractor protection valve and parking brake valve should pop out on a tractor-trailer combination vehicle when the air pressure falls to the manufacturer’s specification (20 – 45 psi). This will cause the spring brakes to come on.

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15
Q
  1. What is a converter dolly?
A

a coupling device of one or two axles and a fifth wheel

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16
Q
  1. Describe what the trailer air supply control does.
A

keeps air in the tractor or truck brake system should the trailer break away or develop a bad leak.

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17
Q

How can you check slack adjusters?

A

Chock the vehicle and release the park brake

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18
Q
  1. What type of trailers can get stuck on the railroad-highway crossings?
A

Low slung units (lowboy, car carrier, moving van, possum-belly livestock trailer); Single-axle tractor pulling a long trailer

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19
Q
  1. 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?
A

• Rear of front trailers: OPEN; Rear of last trailer: CLOSED; Converter dolly air tank drain valve: CLOSED

20
Q
  1. Describe what the service line is for.
A

trailer brakes

21
Q
  1. How do you check to make sure trailer height is correct before coupling?
A

It must be slightly lower than the center of the fifth wheel so trailer is raised slightly when dolly is pushed under

22
Q
  1. What is off-tracking?
A

When a vehicle goes around a corner, the rear wheels follow a different path than the front wheels.

23
Q
  1. What three methods can you use to secure a second trailer before coupling?
A

Drive tractor close to the trailer and connect the emergency line charge the trailer air tank and disconnect the emergency line. This will set the emergency brakes

24
Q
  1. After coupling, how much space should be between the upper and lower fifth wheel?
A

no space

25
Q

How should you brake when you drive a tractor-trailer combination with ABS?

A

Normally

26
Q
  1. How do you know if your trailer is equipped with antilock brakes?
A

Warning Indicators on the control panel or label on the side of the trailer

27
Q

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

A

TRUE

28
Q
  1. Why should you not use the trailer hand brake to straighten out a jackknifing trailer?
A

the brakes on the trailer wheels cause the skid

29
Q
  1. To drive you need to raise the landing gear only until it just lifts off the pavement. True or False?
A

FALSE

30
Q
  1. What should you check for when inspecting the converter dolly? The pintle hook?
A

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

31
Q
  1. Which shut-off valves should be open and which closed?
A

Rear of front trailers: OPEN; Rear of last trailer: CLOSED.

32
Q
  1. How can you test the tractor protection valve?
A

At normal pressure, shut the engine off; Step on and off the brake several times to reduce the air pressure; the tractor protection valve control should pop out

33
Q

What is a supply pressure gauge used for?

A

These gauges tell you how much pressure is in the air tanks.

34
Q
  1. When you back a trailer, you should position your vehicle so you can back in a curved path to the driver’s side. True or False?
A

TRUE

35
Q
  1. How do you know if your converter dolly is equipped with antilock brakes?
A

Dollies manufactured on or after March 1, 1998, are required to have a lamp on the left side.

36
Q

What factors can cause brakes to fade or fail?

A

excessive heat caused by using them too much and not relying on the engine braking effect

37
Q
  1. Why should you use chocks when parking a trailer without spring brakes?
A

the air will leak away and then there will be no brakes

38
Q

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

A

To use the engine power as the primary braking source

39
Q

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

A

TRUE

40
Q
  1. When you turn suddenly while pulling doubles, which trailer is most likely to turn over?
A

the rear trailer is twice as likely to turn over as the tractor.

41
Q
  1. How can you test that air flows to all trailers?
A

Use the tractor parking brake or chock the wheels; Wait for normal air pressure, then push in the red “trailer air supply” knob to supply air to the emergency (supply) lines; Use the trailer handbrake to provide air to the service line; at the rear, open the emergency line shutoff valve; You should hear air

42
Q
  1. You should look into the back of the fifth wheel to see if it is locked onto the kingpin. True or False?
A

TRUE

43
Q
  1. What two things are important to prevent rollover?
A

keep the cargo as close to the ground as possible, and drive slowly around turns

44
Q

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

A

TRUE

45
Q
  1. How can you test that air flows to all trailers?
A

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.

46
Q

If you are away from your vehicle only a short time, you do not need to use the parking brake. True or False?

A

FALSE

47
Q

What is a dual air brake system?

A

A dual air brake system has two separate air brake systems, which use a single set of brake controls

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