Air Brake System Flashcards
What pumps air into the air storage
tanks?
Air Compressor
What controls when the air compressor will
pump air into the air storage tanks?
Air Compressor Governor
What is the normal psi range for an air compressor?
100-125 psi
What holds the air in an air brake system?
Air Storage Tanks
What helps prevent the build up of water and oil in the air compressor?
Air Tank Drains
When should the air tank drains be drained?
At the end of every shift.
What device helps to
reduce the risk of ice in air brake valves and other
parts during cold weather?
Alcohol Evaporator
What device protects the tank and the rest of the system from too much pressure?
Safety Valve
What gives a visual of how much air pressure is in the air storage tanks?
Supply Pressure Gage
What shows how much air pressure you are
applying to the brakes?
Application Pressure Gauge
What switches on during emergency and parking braking, when air pressure is absent?
Spring Brakes
Why must air tanks be drained?
To prevent blockages in the tank from frozen liquid during cold weather and to prevent air brake malfunction from excess water and oil.
All vehicles with air brakes must have a low air pressure warning signal. True or False?
True
Front wheel brakes are good under all conditions. True or False?
True
How do you know if your vehicle is equipped with antilock brakes?
The vehicle certification label will indicate if the vehicle is equipped with antilock brakes. It is likely equipped with ABS if it is a truck tractor built after March 1, 1997 or other air brake vehicle built after March 1, 1998.
At what pressure does the low air pressure signal turn on?
Under 60 psi
At what pressure do the spring brakes switch on?
Typically 20-30 psi
What are front brake limiting valves used for?
To reduce the chance of the front wheels
skidding on slippery surfaces.
What system has two separate air brake systems, which use a single set of brake controls?
Dual air brake system, one each for the front and rear axle. Also supplies air to trailer.
Before driving a vehicle with a dual air system what should you do?
Allow time for the air compressor to build up a minimum of 100 psi pressure in both the primary and secondary systems.
What is the device that turns the camshaft and the s-cam when air pressure is applied to the attached rod?
Slack adjuster
How do you check the slack adjustors?
a) Park on level ground, being sure to chock each tire.
b) Release the parking brake.
c) Pull hard on each slack adjustor to check for give. (If
it shifts more than an inch, it needs to be adjusted.)
How can you test the low-pressure warning signal?
a) Once the air pressure has reached 125 psi, turn the
engine off.
b) Turn on power and apply the brake to release air
pressure.
c) If the warning signal does not come on before the
pressure drops below 60 psi, it needs to be fixed.
How can you check that the spring brakes come on automatically?
a) With engine off and power on, repeatedly apply the
service brake to lower air pressure.
b) The tractor protection valve and the parking valve
should pop out when the pressure drops to about 20-
45 psi.
What are the maximum leakage rates?
The maximum air leakage rate for a tractor is 2 psi/min and 3 psi/min for a tractor trailer.
Why should you be in the proper gear before starting down a hill?
It is important to use to take advantage of the slowed down engine over solely using brakes to slow down when descending a hillside. This is because overuse of the service brakes can cause overheating resulting in brake fade, which will reduce the efficacy of the brakes stopping power.
What factors can cause brakes to fade or fail?
When the service brakes are overused the brakes can overheat resulting in brake fade. Additionally, when some of the brakes are not properly adjusted the properly adjusted brakes will be forced to overcompensate causing them to overheat and result in brake fade.
The use of brakes on a long, steep downgrade is only a supplement to the braking effect of the engine. True or False?
True.
If you are away from your vehicle only a short time, you do not need to use the parking brake. True or False?
False.
How should you brake when you drive a tractor-trailer combination with ABS?
Use the service brakes only when needed to maintain control and to stop the vehicle. When slowing be sure to monitor the trailer and slowly reduce pressure applied to the brake pedal.
You still have normal brake functions if your ABS is not working. True or False?
True.
