Arizona Air Brakes CDL Practice Test

What is the third system combined in modern air brake systems, alongside the service brakes and parking brakes?

1. S-cam brakes.

2. Drum brakes.

3. Foot brakes.

4. Emergency brakes.

The correct answer is: Emergency brakes.

The third system combined in modern air brake systems, alongside the service brakes and parking brakes, is the emergency brakes. Emergency brakes are designed to activate in the event of a brake system failure or other emergency situations. They provide a backup mechanism to help bring the vehicle to a stop when the service brakes fail, ensuring greater safety for the driver and others on the road. The inclusion of emergency brakes is crucial because they utilize a different mechanism that is typically independent from the service brakes. This means that if there is a failure in the primary braking system, the emergency brakes can still function effectively to prevent an accident. In many vehicles, emergency brakes are activated either manually by the driver or automatically in certain conditions. Service brakes are the regular brakes used for everyday driving, while parking brakes are specifically designed to hold the vehicle stationary when it is parked. Understanding the role of emergency brakes helps drivers appreciate the multi-faceted nature of air brake systems and enhances their overall safety awareness when operating commercial vehicles.