Arizona Air Brakes CDL Practice Test

An emergency brake...

1. Is required on commercial vehicles

2. Must be held on by mechanical force

3. Could be activated by the loss of air pressure

4. All of the above

The correct answer is: All of the above

An emergency brake is an essential component of commercial vehicles, serving crucial safety functions. The requirement that it be present in commercial vehicles ties into regulations designed to ensure that these vehicles can be safely stopped in the event of a failure of the primary braking system. This stipulation is in place to protect both the driver and other road users. The requirement for the emergency brake to be held on by mechanical force indicates that it should remain engaged without needing constant input from the driver. This design ensures that if the driver is unable to maintain pressure for braking through other means, the vehicle remains safely immobilized, further enhancing safety. Additionally, the possibility of the emergency brake being activated by the loss of air pressure is a critical feature. In air brake systems, when air pressure drops below a certain threshold, the emergency brake automatically engages to prevent the vehicle from rolling, which is a significant safety measure in air brake systems. Collectively, these points contribute to making the answer comprehensive, affirming that all of these characteristics are integral to the design and function of emergency brakes in commercial vehicles.