Air Brake Practice Test

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Prepare for the Air Brake Test with flashcards and multiple choice questions, each offering hints and explanations. Get set to ace your test!

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What are spring brakes?

Air brakes
Trailer brakes
Emergency/parking brakes

The correct answer is: Emergency/parking brakes

Spring brakes serve as both emergency and parking brakes in air brake systems. They consist of a large spring that is compressed when the vehicle is in operation and then engaged to the brake system when there is a loss of air pressure. This characteristic ensures that the brakes automatically apply in the event of a system failure or when the driver turns off the engine, thereby preventing the vehicle from rolling away. Spring brakes are designed to engage when the air pressure drops below a certain threshold, utilizing the force of the spring for both emergency situations and as a means for securing the vehicle when parked. This is particularly important for heavy vehicles, where trailing loads can make them susceptible to movement on inclines. By providing reliable braking under these conditions, spring brakes play a critical role in both the safety and operational functionality of a vehicle equipped with air brakes.