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CDL Air Brakes Endorsement
To check the slack adjusters on S cam brakes, you should:
Wear gloves and pull hard on each slack adjuster.
To test the low pressure warning signal, you should (3):
* Shut the engine off
* Turn the electrical power on
* Step on and off the brake pedal to reduce air pressure.
With dual air systems, the air pressure should build:
From 85 to 100 psi in 45 seconds.
With single air systems, the air pressure should build:
From 50 to 90 psi in 3 minutes.
To test air leakage rate you should:
Turn off the engine and release the service brake.
To check the air compressor governor "cut in" and "cut out" pressures (3):
* Run the engine at a fast idle
* Pump the brake to reduce tank pressure
* Monitor the air pressure gauge
The governor allows the air to start pumping again when it reaches the cut in level or around:
The governor stops pumping air when it reaches the "cut out" level, or around:
You should use the parking brake:
Any time you park.
To test your service brakes you should:
Release the parking brake, move forward slowly and press the brake pedal.
A combination vehicle air brake system should not lose air faster than:
3 psi per minute
The safety valve in the air compressor tank is set to open at:
When the safety valve releases air it means that (3):
* The pressure has exceeded 150 psi
* Too much air is in the air compressor
* Something is wrong and you should have it checked by a mechanic
When the low pressure warning is activated, you should:
Bring the vehicle to a safe stop while you still have braking control.
Stab braking occurs when you (3):
* Press on the brake pedal as hard as you can
* Release the brakes when the wheels lock up
* Apply the brakes when the wheels start rolling
A fully charged air system typically has how many psi?
Compressed air is stored:
In the storage tank(s)
The Air Compressor Governor controls:
When the air compressor pumps air into the storage tanks.
Which type of brake is the most common in commercial vehicles?
S Cam brakes
An air tank is equipped with a drain valve to remove:
Water and Oil
Air brakes take longer to stop than hydraulic brakes because:
It takes longer for the air to flow through the lines
The air compressor is connected to the engine through:
Gears and hoses
Some air brake systems have an alcohol evaporator which helps:
Reduce the risk of ice in the air brake valves during cold weather.
All vehicles with air brakes are required to have a low pressure warning signal. This could be (3):
* A red light
* A wig wag mechanical arm
* A buzzer
The air tank should be drained how frequently:
Once a day
Where are the brake drums located (3)?
* Are bolted to the wheels
* At each end of the vehicles' axles
* Hold the brake shoes and linings
A dual air brake system:
Has two air brake systems and one set of controls
The proper way to go down long grades is to:
Use a low gear and apply light pressure on the brakes.
When you apply pressure to the brake pedal, you are:
Pushing against a spring and against air pressure to the brakes.
An emergency brake (3):
* Is required on commercial vehicles
* Must be held on by mechanical force
* Could be activated by the loss of air pressure
An air pressure gauge:
Shows how much pressure you are applying to the brakes
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