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Class B CDL > Air Brakes > Flashcards

Air Brakes Flashcards

1
Q

A low air pressure warning signal should activate:

A

When tank pressure falls below 60 psi.

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2
Q

Why should you regularly drain the air tanks?

A

Because compressed air contains some water and the water collects in the
tanks

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3
Q

Vehicles equipped with Anti-Lock Braking Systems (ABS) have ____ malfunction lamps
to indicate when the ABS is not working

A

Yellow

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4
Q

A dual air brake system:

A

Consists of two separate air brake systems that share a single set of controls.

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5
Q

A safety valve is set to open at ____ pounds per square inch (psi).

A

150

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6
Q

Air pressure should build up in a single air system within:

A

Three minutes.

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7
Q

Some air brake systems use alcohol:

A

To reduce the risk of ice forming in air brake valves.

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8
Q

Spring brakes come on

A

When too much air pressure is lost.

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9
Q

On trucks and buses, where are ABS malfunction lamps located?

A

On the instrument panel

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10
Q

Before driving a vehicle with a dual air brake system, you must wait for the air
compressor to build a minimum of ____ in both the primary and secondary systems.

A

100 psi

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11
Q

Anti-Lock Braking Systems (ABS)

A

Are equipped in addition to other braking systems and do not reduce normal
braking power.

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12
Q

If using air tanks with manually operated drains, how often should you drain the tanks?

A

Every day

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13
Q

The parking brake should be:

A

Used whenever you park your vehicle.

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14
Q

If the brake pads rub against the brake drums and create too much heat:

A

The brakes may stop working

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15
Q

A low air pressure warning signal:

A

Is required on vehicles with air brakes.

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16
Q

Foundation brakes are used

A

At each wheel.

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17
Q

The air compressor governor controls:

A

When the air compressor pumps air into the air storage tanks.

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18
Q

When traveling down a steep downgrade:

A

Shift into a lower gear, then use brakes to supplement the braking effect of the
engine.

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19
Q

To confirm that a trailer has ABS, you can:

A

Look under the trailer for wheel speed sensors coming from the back of the
brakes.

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20
Q

Dollies equipped with ABS are required to have malfunction lamps located where?

A

On the left side

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21
Q

The ____ tells a driver how much pressure is in the air tanks

A

Supply pressure gauge

22
Q

When inspecting your brakes, a slack adjuster should move ____ from where it is
attached to the push rod.

A

No more than one inch

23
Q

Before driving a vehicle with air brakes, you should ensure that the spring brakes come
on automatically when:

A

Air pressure falls below 45 psi.

24
Q

During an applied leakage test, the maximum leakage rate for a double combination
vehicle is:

A

4 psi in a minute.

25
Q

During an applied leakage test, the maximum leakage rate for a triple combination
vehicle is:

A

6 psi in a minute.

26
Q

Front wheel braking works:

A

Under all conditions.

27
Q

When you press the brake pedal in a vehicle with S-cam brakes, air pressure pushes out
the rod and moves the

A

Slack adjuster.

28
Q

Friction inside a brake drum is caused when the brake shoes and linings:

A

Push against the inside of the drum.

29
Q

Braking mechanisms are located ____ a brake drum.

A

Inside

30
Q

When a brake pedal is pressed and the S-cam is turned, the S-cam:

A

Presses the brake shoes against the inside of the brake drum.

31
Q

To inspect slack adjusters on S-cam brakes, you need to:

A

Chock the wheels and disengage the parking brake.

32
Q

How should you test the low pressure warning signal?

A

Rapidly press and release the brake pedal.

33
Q

Before starting down a hill, be sure to:

A

Switch into a low gear.

34
Q

During an applied leakage test, the maximum leakage rate for a single vehicle with air
brakes is

A

3 psi in one minute

35
Q

During a static leakage test, the maximum leakage rate for a double combination
vehicle is:

A

3 psi in one minute.

36
Q

During a static leakage test, the maximum leakage rate for a triple combination vehicle
with air brakes is ____ in a minute

A

5 ps

37
Q

During a static leakage test, the maximum leakage rate for a single vehicle with air
brakes is ____ in one minute.

A

2 psi

38
Q

While driving, spring brakes are generally held in place by

A

Air pressure.

39
Q

The emergency brake system uses:

A

Parts of both the parking and service brake systems.

40
Q

A modulating control valve can control the

A

Spring brakes.

41
Q

During a walk-around inspection, ensure there are no cracks on the brake drums that
are more than ____ of the width of the friction area.

A

One hal

42
Q

The air pressure in a dual air brake system should build from 85 to 100 psi within:

A

45 seconds.

43
Q

In cold weather, an alcohol evaporator should be checked and filled:

A

Every day.

44
Q

Applying the brake pedal causes air pressure to activate an electric switch and:

A

Turn on the brake lights.

45
Q

A one-way check valve:

A

Prevents air from escaping if the air compressor has a leak.

46
Q

An air compressor governor will stop the compressor from pumping air once the air
tanks have an air pressure level of:

A

125 psi

47
Q

While driving downhill, you should brake until you reach a speed that is ____ below
your safe speed, then release the brake pedal

A

5 mph

48
Q

When you need to stop in an emergency, you should:

A

Stop in a way that keeps your vehicle in a straight line.

49
Q

If braking at a speed of 55 mph while driving on dry pavement, the brake lag can add
____ to your vehicle’s total stopping distance

A

32 feet

50
Q

An air brake-equipped vehicle traveling at a speed of 55 mph under ideal driving
conditions will need approximately ____ to come to a complete stop

A

450 feet

Class B CDL (2 decks)

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