CDL Air Brakes TestAir Brake System PartsEasy
A technician is performing maintenance on a commercial vehicle's air brake system. They are inspecting the spring brakes. What is the primary function of the spring brakes?
- ATo assist the service brakes in emergency stopping situations.
- BTo regulate the amount of air pressure reaching the brake chambers from the foot valve.
- CTo act as an emergency and parking brake, applying automatically when air pressure drops.
- DTo provide primary braking force during normal driving conditions.
Show answer & explanationAnswer & explanation
Correct answer: C. To act as an emergency and parking brake, applying automatically when air pressure drops.
Spring brakes are designed to engage automatically when air pressure drops below a safe level (emergency brake) or when the parking brake control is applied (parking brake). They use powerful springs to apply the brakes, providing a fail-safe mechanism.
Why the other options are wrong
- A. While they can act as an emergency brake, their primary design is for parking and automatic application upon air loss, not to 'assist' service brakes in normal emergencies.
- B. This describes the function of the foot valve, not spring brakes.
- D. The service brakes (foot pedal) provide primary braking force.
Spring Brakes
Powerful springs that apply the brakes when air pressure is removed or drops below a critical level. They serve as both an emergency brake and a parking brake.
- Held 'off' by air pressure.
- Engage automatically if air pressure fails (emergency).
- Engage when parking brake control is pulled (parking).
Memory trick: Springs Bring Brakes On for Parking and Peril.