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Airbrakes > Air Brakes > Flashcards

Air Brakes Flashcards

1
Q

What is max weight on rear axle

A

9100kg (20,000lbs)

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2
Q

Why air brakes?

A

They develope a great force to stop a heavy vehicle

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3
Q

Legal height of vehicle ?

A

4.15metres (13’7”)

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4
Q

Legal width?

A

2.6m (8’6”ft)

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5
Q

If vehicle is 2x as heavy it will take…

A

2x as long to stop

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6
Q

If driving 2x as fast it will take

A

4x as long to stop

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7
Q

If 2x weight AND speed…

A

8x as long to stop

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8
Q

When checking belt tension

A

It should not move more than twice the width of the belt

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9
Q

What is compressed air

A

Air that is squeezed into a smaller space than it normally occupies

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10
Q

Size of reservoir must be..

A

Big enough to apply the brakes 10-12 times

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11
Q

Normal air brake pressure is

A

125 psi(862kpa)

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12
Q

How often should you look at the gauges

A

Frequently

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13
Q

When air leaves the compressor it will be at…

A

204 degree C

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14
Q

Why is water harmful in reservoir?

A

Freezes in cold weather

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15
Q

What does an alcohol evaporator do?

A

Prevent the reservoir from freezing

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16
Q

Compressor must build air pressure from… ___ to ____ in less than ____ minutes at fast idle (1100 rpm’s)

A

50-90 psi , less than 3 minutes

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17
Q

When compressor stops pumping air it goes into the

A

Unloading phase

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18
Q

When compressor starts pumping air it goes into the

A

Loading phase

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19
Q

All air valves do 3 things

A

Open, close, exhaust

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20
Q

Max air pressure must be between

A

105-135 psi

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21
Q

Lowest pressure can go before compressor must turn on

A

80-85 psi

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22
Q

At what pressure will safety valves blow

A

150 psi

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23
Q

If safety valve blows what is not working properly?

A

The Governor

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24
Q

What pressure will the low air alarm go off?

A

60 psi

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25
Q

What to do if low air alarm goes off?

A

Pull over

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26
Q

Supply line (emergency line) is always…

A

Under full reservoir pressure and is color coded RED

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27
Q

Service like is only charged with air when

A

The driver depresses the brake

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28
Q

What color is service line to trailer

A

Blue

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29
Q

How do you keep supply/service lines/glad hands clean

A

Hook them together

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30
Q

5 basic components of air brake systems

A

Compressor, reservoir, foot valve, foundation brakes, air lines

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31
Q

What temp does brake drum START to fail

A

250 degree c

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32
Q

Max pressure lost on a leak test (single unit)

A

Can not exceed 3 psi in one minute

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33
Q

Max pressure lost on a leak test (1 trailer)

A

Can’t lose more than 4psi in one minute

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34
Q

Max pressure lost on a leak test (2 trailer)

A

Can’t be more than 6psi in one minute

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35
Q

Primary reservoir feed which brakes

A

Rear drive

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36
Q

Secondary reservoir feed which brakes

A

Front steer

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37
Q

How many reservoirs in a dual air brake system

A

Three

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38
Q

Slack adjuster has 3 job

A

Adjust brakes -10 thou, change pull/push force into torque , Lever (multiplier of force 6:1)

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39
Q

If checking push rod travel

A

It should not exceed 3/4 of an inch (by hand)

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40
Q

If using 2 people to check push rod travel it should not exceed

A

Not exceed 1 and 3/4 (by air pressure)

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41
Q

How is the heat dissipated that is generated by breaks?

A

Absorbed by the brake drums and disappeared into the atmosphere

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42
Q

If one set of brake shoes is poorly adjusted, what effect could it have on the remaining set of brake shoes in the system

A

They would increase their share of the braking, possibly causing overheating

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43
Q

If 40 psi is exerted againsts a diaphragm of 30 square inches in area, what is the total force that could be exerted

A

1200 LBS (NOT PSI)

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44
Q

Whst pressure should the governor cause the compressor to return to its loading stage

A

80-85psi

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45
Q

How often should the reservoir be drained

A

Daily, or more often during extreme conditions

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46
Q

Signs posted in advance to a downgrade, instructing drivers of trucks to stops inspect their brakes are

A

Regulatory signs

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47
Q

How are most compressors lubricated today

A

From the engine lubricsting system

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48
Q

When air pressure in the reservoir is at its maximum the compressor is

A

Unloaded

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49
Q

If slack adjusted travel is checked while someone makes a brake application, travel should not exceed

A

1 3/4 inch

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50
Q

If the compressor discharge line is broken, what prevents total loss of air?

A

The one way check valve

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51
Q

What is the final factor that will determine if the vehicle will move

A

Traction

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52
Q

What is the main cause of brake fade at high temps

A

The brake drums expand AWAY from the linings

53
Q

What is meant by braking distance

A

The distance the vehicle travels after the brake is applied until the vehicle stops

54
Q

If a small leak develops in a brake chamber, what valve will continue to hold the same application of the chamber?

A

Treadle (foot valve)

55
Q

The main reservoir gauge reads

A

Pressure available for service

56
Q

In which direction should the adjusting nut be turned to tighten the brakes

A

Make the S-Cam shaft rotate in the same direction as an air application

57
Q

Compressor must build up reservoir pressure with an engine at a fast idle from 50-90psi within

A

3 minutes

58
Q

On a long steep downgrade , the best method of descending would be:

A

Use correct gear and engine retsrder and don’t use brakes

59
Q

Automatic slack adjuster violation is

A

2 inches

60
Q

Which way do you turn an automatic slack adjuster with a HEXAGONAL nut?

A

Clockwise

61
Q

Which way do you turn an automatic slack adjuster with a SQUARE nut?

A

Counterclockwise

62
Q

Relay valve does 2 jobs

A
  • quick application of brakes
  • quick release of brakes
63
Q

Spring brakes..

A

Are the opposite of regular brakes

64
Q

Where would an air dryer be installed in a air brake system

A

Between compressor and first reservoir

65
Q

The valve that allows for rapid exhaust at the brake chamber is the

A

Quick release valve

66
Q

When should a driver use the manual front wheel limiting valve

A

When necessary on slippery roads, to reduce front wheel application by 50%

67
Q

Besides psi, air can also be measured in

A

kpa

68
Q

The best way to avoid compounding is

A

Park brake should be released before a foot brake application is made

69
Q

The parking brake control valve is usually what color

A

Yellow

70
Q

Every carrier you work for must check your driving record

A

Before hiring you, and once a year after hiring you

71
Q

The proper technique, when using ABS, is to:

A

Apply a firm application on the brake pedal and allow ABS to operate

72
Q

These provide an auxiliary slowing effect and assist the main brake system to slow the vehicle

A

Retarders

73
Q

If the service brakes are out of adjustment, the spring brakes will be

A

Less powerful for parking

74
Q

The SIX main components of a basic air brake system are:

A

Compressor, governor, reservoir, air lines, foundation brakes, foot valve

75
Q

What is the purpose of the spring brake modular valve

A

Provides controlled rear braking if the primary system fails

76
Q

The spring parking brake emergency release system will allow the driver to

A

Move a disabled vehicle to safety

77
Q

Best way to avoid compounding?

A

Release spring brake before making a heavy service brake application

78
Q

On an air brake equipped vehicle , brake adjustment can be check from which location?

A

When the driver is underneath the truck and trailer

79
Q

If reservoirs are equipped with automatic drain valves, reservoirs

A

Should still be drained regularly to check for moisture

80
Q

To test the holding power of spring brakes, a driver should

A

Complete a tug test , in low gear, with the spring brake applied

81
Q

How much pressure should you apply to the foot valve when measuring slack adjustment using the applied stroke method?

A

90-100psi

82
Q

Why are drivers required to do a pre trip inspection

A

It is the law

83
Q

Following distance in a bus, truck, or heavy vehicle should be no less than

A

5 seconds

84
Q

What is the fine for brakes being out of adjustment?

A

Up to 2,000$

85
Q

The most common cause of loss of effective braking on air equipped vehicles is

A

Brakes out of adjustment

86
Q

What device introduces a small amount of alcohol vapour into the air system

A

Injectors and evaporators

87
Q

What are the brake chambers in an air over hydraulic system?

A

Pressure intensifiers

88
Q

Whst method of checking brakes do roadside inspectors use

A

Applied stroke method

89
Q

What force does the coil spring in spring parking brake chambers exert

A

1500-2000lbs

90
Q

The trailer air supply valve must close if the tractor pressure drops below

A

20 psi

91
Q

Spring parking brakes will come on when applied by the driver and

A

If air pressure drops (below 60psi)

92
Q

Releasing a spring parking brake manually is known as what

A

Caging

93
Q

Which of these is an alternative name for the control line

A

Service line

94
Q

In dual air brake systems using blended air, the parking brake will take air from

A

The tank with the highest pressure

95
Q

Compounding brakes means what

A

Parking brakes and service brakes applying together

96
Q

Safety actuator parking brakes will not release if more than how much air has been lost from the parking reservoir?

A

4 psi

97
Q

An alternative name for the supply line is what

A

Emergency line

98
Q

Spring parking brakes are mounted where on a tractor

A

On the rear axles

99
Q

Which of these is a sign that you may have reversed the supply line and service line connections

A

The spring parking brakes won’t release

100
Q

Using foundation brakes to hold the vehicle when parked is

A

Unreliable, illegal, dangerous, all of these

101
Q

Spring parking brakes will fully apply if air pressure drops to what level?

A

20-45psi

102
Q

When trailer brakes “dynamite” they will remain applied for how long?

A

15 minutes

103
Q

How are safety actuator parking brakes different from normal brake systems

A

The brake chamber has two diaphragms

104
Q

Which of these balances pressure between the service brakes and the spring parking brakes

A

Spring brake modulator

105
Q

Spring brakes are kept off by

A

Air pressure

106
Q

In color coded systems which colour is used to indicate the control line

A

Blue

107
Q

Before manually releasing spring brakes you should do what

A

Chock the wheels

108
Q

The chief difference between a trailer air brake system compared to the tractor is that the trailer will not have

A

A compressor

109
Q

Operating a vehicle with an excessive brake chamber pushrod stroke can result in a fine up to

A

2000

110
Q

By law you must check the manual and automatic slack adjusters

A

Every day

111
Q

When you want to apply the trailer brakes without applying the tractor brakes, what should you use?

A

The hand valve

112
Q

When checking adjustment you should wear

A

Hard hat, eye pro, stout clothing

113
Q

In a type 30 brake chamber, the max available stroke is

A

2.5 inches

114
Q

If your vehicle is equipped with an air dryer system, you need to drain the reservoirs..

A

As often as if the system wasn’t there

115
Q

When using a bobtail proportioning system braking will require

A

Higher than usual pedal pressure

116
Q

A tractor with a bobtail proportioning system will reduce the braking pressure to the drive axle brakes up to

A

75%

117
Q

When the trailer air supply valve is closed, the trailer brakes must

A

Apply fully

118
Q

If a vehicle is equipped with a tractor parking brake valve, it will usually be what colour?

A

Blue button

119
Q

Drum brake linings must be a minimum of Whst thickness

A

1/4 inch

120
Q

Alcohol injector systems are designed to prevent

A

Freezing

121
Q

Automatic slack adjusters need to be checked

A

As often as manual adjusters

122
Q

Brakes need adjustment if the applied stroke is more than

A

1 3/4 inch

123
Q

Your vehicle will have automatic slack adjusters if it was built later than

A

1996

124
Q

Which of these vehicles are you most likely to find air over hydraulic brakes

A

A bus

125
Q

Under what circumstances can you use the hand valve for parking

A

None of them

126
Q

The trailer air supply knob on the dashboard will usually be what shape

A

Octagon

127
Q

If your vehicle has wedge brakes, you will know the automatic slack adjusters have failed if when the brakes are applied and released the linings move more than…

A

1/16 of an inch

128
Q

With brakes on the same axle pushrod travel should be

A

The same on each side

Airbrakes (1 decks)

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