Georgia Commercial Driver License Practice Test

What type of brakes can be released using a separate air tank in a dual parking brake system?

1. Disc brakes

2. Spring brakes

3. Hydraulic brakes

4. Drum brakes

The correct answer is: Spring brakes

In a dual parking brake system, spring brakes are designed to be released using a separate air tank. This is because spring brakes utilize a combination of mechanical springs and air pressure to hold the vehicle stationary when parked. The system is engineered so that when the vehicle is in a parked state, the springs are compressed. When releasing the parking brake, air pressure from the separate tank is directed to the spring brake chambers, which allow the springs to decompress and release the brake. This mechanism provides a fail-safe option; if there is a loss of air pressure while driving, the spring brakes will automatically engage, helping to prevent rollaway. Spring brakes are commonly found on commercial vehicles, making them essential for safety in large trucks and buses where significant stopping power is required, and where traditional friction brakes may not be sufficient for preventing slide or roll when parked. Other brake types, such as disc, hydraulic, or drum brakes, do not typically operate using a separate air tank in the same manner, as their designs and mechanisms differ significantly from those of spring brakes in a dual parking brake configuration. This is why the correct answer specifically identifies spring brakes.