問題一覧
1
During normal, spring brakes are usually held back by ?
air pressure
2
The break pedal in an air break system ?
controls the air pressure applied to put on the brakes
3
The brakes system that applied and releases the brakes when the driver uses the brake pedal is what system?
service system
4
All air brakes equipped vehicles must have what?
a supply pressure guage
5
If your truck or bus has a dual parking control value, you can use pressure from another tank to ?
release the spring brakes to move vehicle in an emergency
6
The most common type of foundation brake found on heavy vehicle is the ?
s-cam drum brakes
7
Parking or emergency brakes if trucks and buses can be legally held on by what?
spring pressure
8
If your vehicle had and alcohol evaporator, is is there to ?
reduce the risk of ice in value and other parts in cold weather
9
Some air brakes system have alcohol evaporator. What might happen if you don’t keep the unit full with alcohol?
ice may form in the tanks and cause the brakes to fail
10
The most important thing to do when the low air pressure warning comes on is ?
stop and park safely as soon as possible
11
The driver must be able to see a low air pressure warning that must come on before pressure in the thank fall below what ?
60 psi
12
Under normal conditions, in order to engage the parking brake the driver must first ?
let the air out of the system
13
To check the free play of manual slack adjusters on s-cam brakes, you should park on?
level ground,chock the wheels,and release the parking brake
14
For air brakes system in good condition, the air compressor should start pumping at what psi?
100
15
A straight truck or bus system should not leak at a rate of more than ? Psi per minute with the engine off and the brakes released?
2 psi
16
A slack adjuster probably need adjustment if it moves more than ? Inch when you pull on it.
1 inch
17
If you are driving down a steep downgrade and you have reached your safe speed of 40 mph, you should apply the service brakes until your speed reaches what?
35 mph
18
The use of brakes on a long and/or steep downgrade is only a supplement to ?
the braking effect of the engine
19
Under ideal conditions, a truck with air brakes going 55 mph would require a stopping distance of what?
more than 300 feet
20
Emergency stab braking is when you ?
brake as hard as you can, release the brakes when the wheel lock, and apply the brakes again when the wheels roll
21
The braking power of the spring brake?
depends on the brakes being in adjustment
22
If you must make an emergency stop you should brake so you ?
can keep your vehicle in a straight line and turn if it becomes necessary
23
The proper method of braking when going downhill is to reduce your speed by ? Mph below your safe speed before releasing the brakes?
5 mph
24
Which of the following about ABs is true?
ABS changes the way you brake in an emergency
25
If your ABS is not working, you should?
drive normally, but get the service soon
26
The stop light switch ?
turn on the break lights to warn others behind you
27
If air pressure does not build up to normal within the correct amount of time ?
your air pressure may drop to low while driving, require an emergency stop
28
If the spring brakes are on, when should you push the brake pedal?
never
29
If your trucks compressor has it own oil supply,when should you first check the oil level?
before driving
30
The safety value is set automatically to reduce pressure in the tanks at what psi?
150 psi
31
The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than what?
3psi in 1minute
32
Air brakes takes more time to stop hydraulic brakes because?
air takes more time to flow through the lines than hydraulic fluid
33
In air brake vehicles, the parking brake should be used ?
anytime the vehicle is parked
34
Which of these is not a proper time to apply the parking brakes ?
if the brakes are very hot
35
Emergency controlled braking is when you ?
apply the brakes as hard as you can without locking the wheels
36
The application pressure gauge show how much pressure ?
you are applying to the brakes
37
The supply pressure gauge shows how much pressure ?
is in the air tank
38
How often should you drain the water end oil from your air tanks?
at the end of each day of driving
39
The spring brakes on a truck will bring it to a stop automatically, when air pressure falls to what range?
20-45 psi
40
The air compressor should start pumping at what psi?
125 psi
41
Modern air brakes combine 3 different systems?
the service,parking,and emergency brakes
42
The s-can ?
forces the brake shoes to the drums
43
If your truck has a dual air system, and 1 system is low on air pressure ?
either the front or rear brakes will not be operating fully
44
Excessive use of the service brakes results in overheating, which can lead to ?
expansion of the brake drum
45
If your truck has a properly functioning fuel air system, the pressure should build from 85 psi too 100 psi in how long?
45 seconds
46
You should know that your brakes are fading when ?
you have to push harder and harder on the brake pedal to control your speed
47
How should you check that your device brakes are working properly?
park on level ground, release parking brakes, roll forward slowly and apply the brakes using the pedal
48
Total stopping distance for air brakes is longer than hydraulics because of what ?
brake lag
49
Excessive heat caused by using your brakes too often can cause the ?
brakes to fade or fail
50
If a truck or bus has ABS, it will have a ? Malfunction lamp on the instrument panel.
yellow
51
The modulating control value allow you to operate the ?
spring brakes
52
Cracks in the drum can not be longer than ? the width of the friction area.
1/2
53
The air brake lag at 55 mph adds how much feet stopping distance?
32 feet