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CDL Test > Air brakes > Flashcards

Air brakes Flashcards

1
Q

When is it ok to leave your truck unattended without applying the parking brakes and choking the wheels?

A

Never

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2
Q

the stop light switch

A

turn on your brake lights to warn drivers behind you

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3
Q

is not safe to drive a vehicle that has brake drums with cracks that are longer than BLANK of the width of the friction area

A

1/2

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4
Q

to test air service brakes you should:

A

brake firmly while slowly moving forward

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5
Q

a slack adjusters free play needs to be adjusted if it is more than about BLANK how many inches when you pull hard on it

A

1 INCH

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6
Q

if air pressure is not built up within the correct amount of time, then

A

you air pressure may drop to a low point while driving, requiring an emergency stop

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7
Q

the saftey valve reduces pressure at BLANK psi

A

150 PSI

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8
Q

why should you drain the water from compressed air tanks?

A

water can freeze in cold weather and cause brake failure

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9
Q

if your vehicle has an alcohol evaporator, every day cold weather you should

A

check and fill the alcohol level

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10
Q

the air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than

A

3 psi in 1 minute

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11
Q

the driver must be able to see a low pressure warning which comes on before pressure in the service air tanks falls below

A

60 psi

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12
Q

the air brake lag distance at 55 mph on dry pavement adds about BLANK feet

A

32 feet

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13
Q

if your truck has a properly functioning dual air brake system and minimum size air tanks that air pressure should build up from 85 to 100 psi within how many seconds

A

45 seconds

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14
Q

how should you check that your service brakes are working properly

A

park on a level ground, wait until normal air pressure is reached, release the parking brake and move forward slowly at 5 mph, than apply the brakes firmly using the brake pedal

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15
Q

a straight truck or bus air brake system should not leak at the rate of more than BLANK psi per minute with the engine off and the brakes released

A

2 psi

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16
Q

excessive use of the service brakes result in over heating which can lead to

A

expansion of the brake drums

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17
Q

the safety valve is set automatically when pressure is

A

150 psi

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18
Q

you truck and bus has a dual air brake system. if a low air pressure warning comes on for only one system, what should you do

A

stop right away and safely park. continue only after the system is fixed

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19
Q

to check the free play of manual slack adjusters of s-cam brakes, you should park on

A

level ground, chock the wheels and release the parking brakes

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19
Q

if you must make an emergency stop, you should brake so you

A

can steer and so you vehicle stays in a straight line

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19
Q

the brake pedal in an air brake system

A

control the air pressure applied to put on the brakes

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19
Q

all air brakes equipped vehicles have

A

a supply pressure gauge

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19
Q

a straight truck or bus air brake system should not leak at the rate of more than BLANK psi per minute with the engine off and brakes released

A

2 psi

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19
Q

with air brake vehicles, the parking brakes should be used

A

whenever you leave the vehicle unattended

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20
Q

the use of brakes on a long and steep downgrade under normal conditions is only a supplement to

A

the braking effect of the engine

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21
Q

the most important thing to do when a low pressure warning comes on is

A

stop and safely park as soon as possible

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22
Q

the parking or emergency brake on a heavy vehicle can only be held in position by something that cannot leak away like

A

spring pressure

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23
Q

why drain water from compressed air tanks

A

water can freeze in cold weather and cause failure

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24
Q

repeatedly partially releasing and pressing the brake pedal may result in

A

a loss of brake air pressure

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25
Q

the brake pressure system that applied and releases the brakes when the driver uses the brake pedal is the BLANK brake system

A

service

26
Q

a slack adjusters free play needs to be adjusted if it is more than about BLANK how many inches when you pull hard on it?

A

1 inch

27
Q

an air brake system is fully charged at what PSI

A

125 psi

28
Q

if the spring brakes are on, when should you push the brake pedal

A

Never

29
Q

when the brakes are applied the brakes shoes will press against

A

brake drum or disc

30
Q

the safety valve discharges automatically at the pressure of

A

150 psi

31
Q

emergency stab braking is

A

press on the brake pedal as hard as you can, release the brakes when the wheels locked, put on the brakes again when the wheels start rolling

32
Q

why should you drain water from compressed air tanks

A

water can freeze in cold weather and cause brake failure

33
Q

modern air brakes systems combine 3 different systems. they are

A

Service
parking
emergency

34
Q

if you have automatic tank drains, how often should you drain the oil and water from the bottom of compressed air storage tanks

A

at the end of each day of driving

35
Q

the proper use of the brakes when going down a long steep grade after selecting a proper gear is to brake until your speed is about BLANK mph below the posted speed for your safety and release your brake

A

5 mph

36
Q

in ideal conditions a truck or bus with an air brake going 55 mph would require stopping of how many feet

A

more than 300 feet

37
Q

the application pressure gauge show how much air pressure you

A

are applying to the brakes

38
Q

the spring brakes used on the chambers in a straight truck will bring you to a stop when the air pressure drops below BLANK psi

A

20 psi

39
Q

some air brake systems had an alcohol evaporator. what may happen if you dont keep the proper level of alcohol?

A

ice may form in the air storage tank and cause brake failure

40
Q

your truck or bus has dual air brake system. if a low air pressure warning comes on for only one system, what should you do

A

bring your vehicle to a complete stop right away and safely park. continue only after the system is fixed

41
Q

when brakes are applied the brake shoes will align to press against the

A

brake drums or disc

42
Q

the braking power of spring brakes

A

depends on the service brakes being in adjustment

43
Q

the driver must be able to see a low air pressure warning which comes on before pressure in the service air tanks falls blow BLANK psi

A

60 psi

44
Q

which of these is not proper time to apply the parking brakes

A

to brake vehicle very hard, in other words when coming down a steep grade

45
Q

if you truck or bus has dual parking control valves, you can use pressure from separate tanks to

A

release the spring emergency/parking brake to move a short distance

46
Q

the most common type of foundation brake found on heavy vehicle is the

A

S-cam drums

47
Q

you truck or bus has dual air brake system, if a low air pressure warning comes on for only one system, what should you do

A

bring your vehicle to a safe stop and safely park, continue only after the system is fixed

48
Q

with air brake vehicle, the parking brakes should be used

A

anytime whe the vehicle is parked

49
Q

excessive heat caused by using the brakes too often can also cause

A

brake to fade or fail

50
Q

if you must make an emergency stop, you should brake so you

A

can steer and so your vehicle stays in a straight line

51
Q

the supply pressure gauge shows how much pressure

A

is in the air tanks

52
Q

if you are driving down a steeo downgrade and you have reached a speed of about 40 mph, you would apply the service brakes until you speed dropped to below BLANK mph

A

35 mph

53
Q

your truck has dual air brake system and one of the system loses pressure. what will happen

A

either the front or back brake will not be fully operational

54
Q

parking or emergency brakes of trucks and buses can be legally held on by BLANK pressure

A

spring pressure

55
Q

the S-cam

A

forces the brake shoes against the inside of the brake drum

56
Q

under normal conditions in order to engage the parking brake driver :

A

let the air out of the air brake system

57
Q

total stopped distance for air brakes is longer than hydraulic brakes due to BLANK distance

A

brake lag

58
Q

is it accepted that too much heat caused by using your brakes too often can also cause

A

brakes to fade or fail

59
Q

during normal driving, spring brakes are usually held back by

A

air pressure

60
Q

the air compressor stops pumping air at what PSI

A

125

61
Q

the supply pressure gauge show how much pressure

A

is in the air tanks

62
Q

the braking power or the spring brakes

A

depends on the service brakes being in adjustment

63
Q

why should you drain water from compressed air tanks

A

water can freeze in cold weather and cause brake failure

64
Q

if you must make an emergency stop, you should brake so you

A

can steer and so you vehicle stays in a straight line

65
Q

your brake are fading when

A

you have to push harder on the brake pedal to control your speed on downgrade

66
Q

if your vehicle has an alcohol evaporator, it is there to

A

reduce the risk of icing in air brake valves in cold weather

67
Q

the air compressor governor controls

A

when air is pumped into the air tanks

68
Q

air braking takes more time than hydraulic braking becuase air

A

takes more time to flow through the lines than hydraulic fluid

CDL Test (3 decks)

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