Air Breakes
Slack adjuster should not have more than blank of play
1 inch
Brake drums must not have cracks longer than what width of the friction area
1/2
The air compressor will stop pumping air into the air tanks at what PsI
125
Atypically air brake system is fully charged at
125 psi
A straight truck or bus air brake system should not leak at a rate of more than. Psi per minute with the engine off in the brakes released
2 PSI
Tracker and straight truck spring break will come fully on when the air pressure drops to a range of
20 to 45 psi
Brake lag distance at 55 mph is how many feet
32
Loss of air in a straight truck or a bus should not be more than blank with the engine off in the brakes applied
3psi in one minute
If your vehicle has a properly functioning door air brake system and minimum size air tank the air pressure should build from 85 to 100 PSI within how many seconds
45
On a long steep downgrade once you have reached your safe speed break until you are traveling
5 mph slower
The driver must be able to see a warning that is giving before air pressure in the service air tanks fall below
60 psi
Repeatedly pressing and releasing fanning the brake pedals may result in
A loss of brake air pressure
The modulating control valve is
A spring loaded valve That will let you put on the brakes on slowly if the Service brakes fail
A converter dolly with ABS brakes is required to have
A yellow lamp on the left side
antilock braking system (ABS)
Activates when your wheels are about to lock up
Oil and water usually collects and compressed air tanks if you do not have an automatic tank drain when should you drain the air tank
After every working day
The brake pad should be for the brakes to be on
Against the Bakes
The brake pad should be at what for the brake pads to be on
Against the brake drums
During normal driving spring breaks are usually held back by
Air pressure
What activates the stop switch
Air pressure
Which vehicle must have low air pressure warning signals
All vehicles with airbrakes currently in operation must have low air pressure warning signals
Under which conditions are front wheel brakes good
All weather conditions
To test the air service brakes
Brake firmly while slowly moving forward.
Which of the following makes a total stopping distance for airbrakes longer than that for hydraulic brakes
Brake lag distance
Spring breaks are
Brakes that comes on automatically on a truck or tractor when the psi drops too low, it's made up Of powerful springs that are held back by air pressure while you are driving, and it's not going to take full effect until your psi drops to a certain range typically 20 to 30 psi
To make an emergency stop with air brakes using the stab break method you should
Break as hard as you can get off the brakes when the wheels lock get back on the brakes when the wheels start rolling again
In control breaking you
Break in a straight line
If your vehicle has an alcohol evaporator every day during cold weather you should
Check and feel the alcohol level
How can you tell if your vehicle is equipped with antilock braking system, ABS
Check if your vehicle was manufactured at the 1998
Air brakes use what to make the brakes work
Compressed air
When you press the brake pedal
Compressed air enters the brake chambers
What is the best way to test if your vehicle spring breaks come on automatically
Continue to step on and off the brake pedal until the manufacturer PSI significations is met for spring breaks to engage, on single vehicles continue to step on and off the brake pedal until the parking brake valve Pop out, on tractor trailer vehicles continue to step on and off the brake pedal until the parking brake valve pop out
If you need to stop quickly in your vehicle lack ABS breaks you can use
Control breaking or the stab braking
The breaking power of the spring breaks
Depends on the adjustment of the service breaks
Which of the following is the most important thing about hard braking
Don't lock the wheels for longer than an instant
Your vehicle has a dual air brake system one of the system loses air pressure what will happen
Either the front or rear brake will not be fully operational
Modern air brake systems are three different systems combine the service breaks the park and breaks and what break
Emergency brake
Modern air brake system combines three different systems they are the service brakes, the parking brakes in the
Emergency brakes
Which of the following can cause brakes to fade or fail
Excessive use of the service breaks, not relying Enough on the engine braking, brakes been out of adjustment
Excessive use of the service brakes may result in overheating which can lead to
Expansion of the brake drums
In which of the following situations should you not apply the parking brakes
If the brakes are very hot
Vehicles with airbrakes must have
In air pressure gauge to show the pressure available for breaking
The application pressure gauge shows how much pressure
Is been applied to the brakes
S cam brakes have a S cam in each brake chamber why is it called in S cam
It is shaped like the letter S
If the lower air pressure warning signal is not working
It may lead to a sudden emergency braking in a single circuit air system
To apply the park and breaks under normal conditions
Let the air out of the brake chambers
The parking brake control
Lets the air out of the brake chamber
Under ideal conditions the average driver of a truck or bus equipped with air brakes and traveling at 55 mph will require what stopping distance
More than 400 feet
If the spring breaks are on when should you push the brake pedal
Never
When can you leave your truck unattended without first applying the parking break or chocking the wheels
Never
Which of the following can cause the brakes to fail or fade
Overheating, low air pressure, and not relying on the engine braking effect
To check the slack adjusters on an S cam brake drum you should first
Park on the level ground chuck the wheels release the parking break
In the event of brake system failure the emergency brake system uses what to stop the vehicle
Parts of the service brakes and parking brake
if your vehicle has a alcohol evaporator it is there to
Reduce the risk of ice in The airBreak valves in cold weather
When driving down a long steep downgrade you should
Release the brakes when you are 5 mph Below your safe speed
If your truck or bus have no parking control valves it means that you can use pressure from a separate tank to
Release the spring break and move a short distance
If your truck or bus have dual parking control valves it means that you can use pressure from a separate tank to
Release the spring breaks to move a short distance
The most common type of foundation brakes found on heavy vehicles is the
S cam brakes
The brake system that applies and release the brakes when the driver uses the brake pedal is the
Service brake system
which of the following should you do before leaving your vehicle unattended
Set the parking brakes, remove the keys, chock the wheels
When S cam brake drums when the brake chambers fill With air, air pressure pushes the push rod out moving the And thus rotating the.
Slack adjuster, and break cam shaft
Before starting down a hill you should be in the Proper gear
So you only had to apply the brakes just hard enough to fill a difinte slow down
The modulating control valves allows you to control the
Spring brakes
What can legally hold a parking or emergency brake in position for a truck truck tractor or bus
Spring pressure
If you must make an emergency stop you should break so that you
Stay in a straight line and can steer
Of the choices below the first thing to do when a low air pressure warning comes on is
Stop in safely park as soon as possible
During your final air brake check if the air pressure does not build up fast enough
The air pressure may drop too low during driving
If oil and water collects in the air tank what could happen to the brakes
The brakes could fail
Excess heat caused by overuse of the service brakes can cause
The brakes to fade
If the air compressor should develop a leak what keeps the air in the tank
The emergency relay valve
How do brakes work on a long steep downgrade
They work as a supplement to the breaking effect of the engine
After the initial drop the maximum acceptable leakage rate per minute are
Three psi for a single vehicle and four psi for a combination vehicle
What is the S cam used for
To apply the brakes
To test the static air leakage rate you should
Turn off the engine release the parking break and let the system settle
How would you check your truck slack adjusters
Use gloves and pull hard on each slack adjuster you can reach
Which of the following are true about a dual air brake system
Usually one system operates the front axle and the other one operates the rear axle, it uses a single set of brake control, one system is called the primary system and the other one is called the secondary system
Why drain water from the compressed air tanks
Water came freeze in cold weather and cause brake failure
The air compressor governor controls
When air is pumped into the air tanks.
What is the best way to test your vehicles low air pressure warning signal
With the engine off step on and off the brake pedal to lower the air pressure below 60 psi
You know that your brake pedals are fading if
You have to press the brake pedal harder than usual to control your speed
You should know that your brakes are fading when:
You must push harder on the brake pedal to control your speed on a downgrade
Which of the following is not part of the braking process when you are driving a tractor trailer combination vehicle with an anti-lock braking system ABS
You should drive faster so that you will be able to keep the trailer and tractor straight
Which of the following will be true about your brake functions if you're anti-braking system ABS fails
You will still have normal braking functions and will just need to get the ABS repaired soon
If the air tanks are not drain daily
Your brakes may feel because of water freezing
Airbrake equipped vehicles must have
supply pressure gauge
