Air Brakes Flashcards
How should you check that the spring brakes come on when the air pressure in the system drops to certain level?
a. park on a level ground, chock the wheels, release the parking brake when you have enough air pressure and shut the engine off and step on and off the brake pedal
b. Park on a light step, drain the air pressure, apply the parking brake and check for movement
c. park on a level ground, wait for the pressure to build up to normal, release the parking brake, move the truck forward and apply the pedal brake as hard as you can
park on a level ground, chock the wheels, release the parking brake when you have enough air pressure and shut the engine off and step on and off the brake pedal
If you don’t have an automatic drain tanks, how often should you drain oil and water that collect at the bottom of the compressed air storage in the air tank?
a. once a week
b. after every 4 hours of service
c. at the end of each day of driving
at the end of each day of driving
The air compressor must stop pumping air at:
a. 125 psi
b. 100 psi
c. 150 psi
125 psi
To check the slack adjusters on S-cam brakes, you should park on:
a. level ground with parking brake, then apply the service brakes
b. level ground and drain the air pressure before adjust the movement of the vehicle
c. level ground, chock the wheels, and turn off the parking brakes
level ground, chock the wheels, and turn off the parking brakes
Tractor and straight truck spring brakes will come fully on when tire pressure drops to:
a. 100 psi
b. 60 psi
c. 20 psi
20 psi
The brake system that apply and release the brakes when the driver uses the pedal brake is the:
a. parking brake system
b. emergency brake system
c. service brake system
service brake system
The hand brake (parking) or emergency brake in a heavy vehicle can be held in position by something like:
a. parking brake system
b. emergency brake system
c. springs
springs
Emergency controlled braking is when:
a. you apply the brakes as hard as you can without locking the wheels
b. apply the brakes as hard as you can, release the brakes when you lock the wheels and apply the brakes again when the wheels start moving
c. apply the hand valve for a second, then apply the brake pedal harder
you apply the brakes as hard as you can without locking the wheels
A pressure gauge tell you how much air there is in:
a. tractor brake lines
b. trailer brake lines
c. air tanks
air tanks
With air brakes there is an added delay than hydraulic brakes because:
a. the air takes more to flow through the lines than hydraulic liquid
b. the air brakes use different brake drums
c. the air brakes require return springs more heavy
the air takes more to flow through the lines than hydraulic liquid
Your vehicle has a dual air brake system. If you receive a low air pressure signal of your secondary system, you should:
a. slow down, and drive to the nearest garage to fix it
b. slow down and test your system while you are on the road
c. bring the vehicle to a safe stop and continue only when the system is fixed
bring the vehicle to a safe stop and continue only when the system is fixed
Under normal conditions, to turn on the parking brakes, the first thing the driver has to do:
a. you have to be sure the air brake system is fully charges
b. release air from the air brake system
c. turn the engine off
release air from the air brake system
All the vehicles equipped with air brakes have:
a. a backup hydraulic system
b. a supply pressure gauge
c. an air use gauge
a supply pressure gauge
You should know that your brakes fail when you:
a. release the brake pedal pressure and hen speed up
b. have to apply hard the brake pedal to control your speed on a downgrade
c. apply the brake pedal and it feels spongy when you apply pressure
have to apply hard the brake pedal to control your speed on a downgrade
Modern air brake systems use three different systems, they are service, hand (parking), and:
a. foot brakes
b. s-cam brakes
c. emergency brakes
emergency brakes
The best way to use the brakes on a long steep downgrade after choosing the proper gear is slowing down until your speed is approximately:
a. 5 miles per hour down your safe speed, then release your brakes
b. 15 miles per hour down your safe speed, then release your brakes
c. 10 miles per hour down your safe speed then release your brakes
5 miles per hour down your safe speed, then release your brakes
The total distance to stop with air brakes is longer than hydraulic brakes because:
a. brake lag distance
b. reaction distance
c. effective braking distance
brake lag distance
The most important thing to do when a low air pressure warning signal turns on is:
a. up the gear shift
b. down the gear shift
c. stop and park safely as soon as possible
stop and park safely as soon as possible
A slack adjuster probably needs to be adjusted if it moves more than, approximately:
a. 1/4 of inch when you pull it hard
b. 1 inch when you pull it hard
c. 1/2 inch when you pull it hard
1 inch when you pull it hard
When is it the right time to leave your truck unattended without applying the parking brakes or chocking the wheels?
a. Never
b. If you are doing a pre inspection before you leave
c. if you will be far from the truck only for a few minutes
never
Why do you have to drain water from the compressed air tanks?
a. the lower level of boiling water reduce the brake power
b. the water can freeze in cold weather and cause brake failure
c. to prevent the oil of the oil compressor from getting dirty
the water can freeze in cold weather and cause brake failure
If the air compressor of your truck may have its own oil supply, when should you check the oil level?
a. before driving
b. immediately after stopping
c. in the first inspection on route
before driving
Foundation brake is the most common type that you can find in heavy trucks is:
a. wedge drum
b. s-cam drum
c. disc brake
s-cam drum
- **The air loss rate on a truck or a straight bus with the engine off and step on the brake pedal should not be more than:
a. 3 psi in one minute
b. 2 psi in 45 seconds
c. 1 psi in one minute
3 psi in one minute
- **An air brake system for truck or a bus should not have leaks more than (engine off and release the brakes):
a. 3 psi by minute
b. 2 psi by minute
c. 1 psi by minute
2 psi by minute
Some air brake systems have an evaporator. What could happen if you didn’t have the alcohol container filled up?
a. it is possible that the s-cam won’t rotate back when you release the brake pedal
b. the air deposits tanks can freeze and cause brake failure
c. brake drums can freeze and it may bend them
the air deposits tanks can freeze and cause brake failure
To test the air service brakes, you should:
a. push the brake pedal hard when you move forward slowly
b. push the brake pedal hard when you move back slowly
c. stop the vehicle, put in a low gear, apply the service brake, and gently push agains the brakes
push the brake pedal hard when you move forward slowly
If your truck or bus has dual parking control valves, you can use air pressure from a separate air tank to:
a. apply more pressure to the brakes if the main tank is low
b. balance the service brake system when you are parking
c. release the emergency spring brakes/hand brakes to move a short distance
release the emergency spring brakes/hand brakes to move a short distance
If your truck has a dual air system and one of the systems has low pressure:
a. brake drums are not pressurized totally
b. the front or the rear brakes will not be operating fully
c. the slack adjusters manual on s-cam brakes are not on
the front or the rear brakes will not be operating fully
The safety valve turns on automatically to reduce pressure at:
a. 150 psi
b. 50 psi
c. 100 psi
150 psi
If you are driving on a steep downgrade and you reach the 40 mph safety speed, you would apply the service brakes until your speed slows down to:
a. 35 mph
b. 30 mph
c. 25 mph
35 mph
For air brake system in good condition, the air compressor should start pumping at:
a. 100 psi
b. 125 psi
c. 150 psi
100 psi
If the spring brakes are on, when should you push the break pedal?
a. only on a slippery road
b. never
c. only when you drive on a steep downgrade
never
It is not safe to drive a vehicle that has brake drums or discs with cracks longer than:
a. 1/4 the width of the friction area
b. 3/4 the width of the friction area
c. 1/2 the width of the friction area
1/2 the width of the friction area
Parking brakes or emergency brakes on trucks and buses can be stopped legally with:
a. air pressure
b. fluid pressure
c. spring pressure
spring pressure
If your vehicle has an alcohol evaporator, every day on cold weather, you should:
a. check the oil for the alcohol contents
b. check the alcohol container and fill it up
c. change the alcohol from a new bottle
check the alcohol container and fill it up
If your vehicle has a alcohol evaporator:
a. this helps to reduce the risk of ice in air brake valves during cold weather
b. it eliminates the alcohol moisture in the tank that condense and then to collect in the bottom of the air tank
c. eliminate the necessity of drain gin the tank everyday
this helps to reduce the risk of ice in air brake valves during cold weather
When you apply the brakes, the brake shoes or lining are pressed against the:
a. brake drum or disc
b. slack adjuster
c. s-cam
brake drum or disc
The brake pedal in the air brake system:
a. control the air compressor speed
b. control the air pressure when you apply the brakes
c. it is connected to the slack adjusters
control the air pressure when you apply the brakes
If the air pressure doesn’t build up to normal fast enough, then:
a. the air pressure could drop too low during driving, requiring an emergency stop
b. you should be ready to use the parking brake to stop the vehicle
c. the alcohol container may be low
the air pressure could drop too low during driving, requiring an emergency stop
Vehicles with air brakes, should use their parking brakes:
a. when you leave the vehicle alone
b. only during inspections before or after the road
c. as little as possible
when you leave the vehicle alone
There is a suspension picture in the exam. They’re leaves in a leaf spring. The question is: If there is one cracked leaf, what is the maximum allowed?
a. 1 inch
b. 1/4 inch
c. 1/2 inch
1/2 inch
Which of these is NOT the correct way to put on the brakes:
a. if the brakes are too hot, after going down a steep road
b. only been stopped for at least one hour
c. you are going to check the parking brake to be sure that you can stop the vehicle
if the brakes are too hot, after going down a steep road
Excessive use of service brakes results in overheating and could lead to:
a. cause expansion of the contact between the brake drums and the brake linings
b. expansion of the brake drums
c. it can get out of adjustment of the s-cam
expansion of the brake drums
The application pressure gauge shows you how much air pressure you:
a. have in the air tank
b. have in the modulating control valve
c. are applying to the brakes
are applying to the brakes
If your truck has a dual air brake system, small air tanks and it works correctly, their pressure should build up from 85 psi to 100 psi in:
a. 60 sec
b. 45 sec
c. 30 sec
45 sec
During normal driving, the spring brakes are held by:
a. spring pressure
b. air pressure
c. bolts
air pressure
The air compressor governor controls:
a. when air pumps to the air tanks
b. the speed of air compressor
c. the air pressure applied to the brakes
when air pumps to the air tanks
When is the safety valve usually set to open?
a. 150 psi
b. 125 psi
c. 100 psi
150 psi
An air brake system is fully loaded when the tank is:
a. 125 psi
b. 75 psi
c. 100 psi
125 psi
When you go on a steep downgrade, and you have to apply your foot hard on the brake pedal to maintain the same speed, this means that your brake is fading, you should:
a. slow down and change to a low gear
b. maintain the same speed
c. slow down and change to a high speed
slow down and change to a low gear
A parking brake control in the cab allows the driver to:
a. let air out of the spring brakes, and this lets the spring put the brakes on
b. control the air of the tanks
c. let air out of the brakes, but it doesn’t let the springs put the brakes on
let air out of the spring brakes, and this lets the spring put the brakes on
What is the valve control modulating?
a. start of the retarders
b. used to apply the spring brakes gradually
c. controls the compressor speed
used to apply the spring brakes gradually
Before driving a vehicle with dual air system, allow time for the air compressor to build up the pressure a minimum of:
a. 80 psi
b. 100 psi
c. 125 psi
100 psi
The brake drums or discs should not have cracks more than:
a. 3/4 of friction area
b. 1/2 of friction area
c. 1/4 of friction area
1/2 of friction area
What are you testing when you wait for normal air pressure, release the parking brake, move the vehicle forward slowly about 5 mph and apply the brakes firmly using the brake pedal?
a. parking brakes
b. service brakes
c. emergency brakes
service brakes
The air brake lag distance at 55 mph on dry pavement adds about 32 feet, so under good traction and brake conditions the total stopping distance is over:
a. 300 feet
b. 100 feet
c. 500 feet
300 feet
Results from excessive heat, causing chemical changes in the brake lining with reduced friction and also causes expansion of the brakes drums, This is called:
a. control brake
b. fail or brake fade
c. parking brake
fail or brake fade
Let hot brakes cool before using the brakes of:
a. emergency
b. parking
c. hand
parking
Pressing and releasing the brake pedal unnecessarily can:
a. change the air pressure of the brake
b. accumulation of air pressure of the brake
c. let air go out and reduce the air pressure
let air go out and reduce the air pressure
How should you check that the service brakes are working properly?
a. Park on a level ground, wait for the pressure to build up to normal and release the parking brake, move the truck forward slowly 5 mph and apply the brake pedal as hard as you can
b. park on a light steep, drain the air pressure, apply the parking brakes and check for movement
c. park on a level ground, chock the wheels, put on the parking brake, when you have enough air pressure to do it and shut the engine off
Park on a level ground, wait for the pressure to build up to normal and release the parking brake, move the truck forward slowly 5 mph and apply the brake pedal as hard as you can
If the service brakes are used too much, they can cause:
a. the spring brake lines to fail
b. the modulated control valve to fail
c. the air brakes to fail
the air brakes to fail
What should you do to stop a trailer jackknife?
a. countersteer the steering wheel
b. use the trailer hand brake
c. release the service brakes
release the service brakes
The modulated control valve allows you to control:
a. the front brakes
b. the air pressure amount of the brake system
c. the spring brakes
the spring brakes
The air brake lag distance at 55 mph on dry pavement adds about:
a. 32 feet to the stop distance
b. 52 feet to the stop distance
c. 72 feet to the stop distance
32 feet to the stop distance
What sentence is true about using retarders?
a. it creates extra heat between the brake shoes or pads and drums or disks
b. brakes used on a steep downgrade increases the engine brake effect
c. you should not use the retarder as the principal way of speed control
you should not use the retarder as the principal way of speed control
During an hydraulic brake inspection, you should pump the brake pedal three times and then verify that it holds for five seconds, if the brakes are working correctly the pedal should:
a. not move
b. slightly pressing
c. down to the floor
not move
You are driving a 40 feet long vehicle at 35 mph. The road is dry and the visibility is good. What is the minimum space you should keep in front of your vehicle to be safe?
a. 5 seconds
b. 4 seconds
c. 3 seconds
4 seconds
The power of the brakes of the spring brakes:
a. depends of the service brakes to be on adjustment
b. is not affected by the service brakes condition
c. increases when the service brakes are hot
depends of the service brakes to be on adjustment
Using the air brakes on a steep down grade, under normal conditions is only a supplement of:
a. using the limiting valve of the front brake
b. using the spring brakes
c. engine brake effect
engine brake effect
If you have to make an emergency stop, brake so:
a. you can steer the wheel and keep your vehicle on a straight lane
b. using the hand brake first
c. you can steer the wheel suddenly and suddenly braking
you can steer the wheel and keep your vehicle on a straight lane
Appears a figure. (BOLA) that shows part of the brake. What holds that part of the brake? a. screws b. pins c. brackets
screws
S-Cam
a. when you press the brake pedal. the air pressure pushes toward the outside of the dip stick. moving the regulator and twisting the dip stick of the excentric brake
b. the push rod of the brake chamber presses spike directly
c. use a power bolt
when you press the brake pedal. the air pressure pushes toward the outside of the dip stick. moving the regulator and twisting the dip stick of the excentric brake
In the air tank, the low air pressure alarm signal turns on before the pressure decreases to:
a. 50 psi
b. 60 psi
c. 80 psi
60 psi
