FREE Air Brake Questions and Answers
In a hand-pull test, how much push rod travel is necessary for the brakes to work?
When using the hand pull method, a cool running temperature and about 1/2 inch of push rod travel are required for efficient braking.
What is the typical operating pressure range of air brake systems?
The most frequent range is 105-125 PSI, while other systems operate at 85-105 PSI.
What stops air from returning to the compressor from the reservoir?
Air cannot return from the reservoirs to the compressor thanks to a one-way check valve. Usually, this valve is spring-loaded.
What happens with a dual circuit air brake system if the air supply to the primary reservoir is cut off?
One reservoir manages the rear brakes and another controls the front brakes in a dual circuit system. Even with one reservoir depleted, the car would still be able to brake, but with less force.
What would happen if you were towing a trailer and the supply line burst?
The spring brakes would lose their retention charge and apply emergency force, locking the trailer tires, if the supply line burst. The tractor would be shielded from a complete loss of air pressure by the tractor protection valve.
How can one minimize brake lag and apply the brakes more quickly by keeping an air supply close to the rear service brakes?
Relay valves provide for quicker application of the brakes by keeping an air charge away from the back brakes, tractor, or trailer.
What produces the air necessary for an air brake system to function?
The compressed air required to run an air brake system is produced by an under-hood compressor.
What does the word "compounding" mean?
Applying a service brake while the spring brakes are still engaged is known as compounding the brakes. High levels of stress are placed on the diaphragms and slack adjusters as a result, which may lead to premature component wear.
What would happen if your service line burst while you were towing a trailer with air brakes?
Unless you applied the service brake, which would release air from the reservoirs, nothing would happen. However, the tractor protection valve would prevent complete loss, allowing the tractor to continue to operate as a brake.
When should the low-pressure warning system activate?
At 60 PSI, the low pressure warning device—which typically included a buzzer, red light, or drop-down indicator—should activate. Check your sensors if it doesn't.
What is the name for using the parking brakes or "spring" in an emergency?
At 45–20 PSI, the main reservoir pressure should trigger an emergency application of the spring brakes.