To apply the parking brake under normal conditions,

To apply the parking brake under normal conditions,

• A. pull the parking brake lever manually
• B. let the air out of the brake chambers
• C. engage the emergency brake switch
• D. turn off the engine

Answer: (B)

In an air brake system, the parking brake is spring-loaded and held off by air pressure. To apply it under normal conditions, you let air out of the brake chambers. When the air is released, the springs push the brake shoes against the drums, locking the wheels in place. This design keeps the vehicle from rolling if you park or if air pressure drops. The other options aren’t how the parking brake is normally engaged: manually pulling a lever isn’t the standard method, the emergency brake switch is meant for emergencies rather than regular parking, and turning off the engine does not engage the parking brake.

In an air brake system, the parking brake is spring-loaded and held off by air pressure. To apply it under normal conditions, you let air out of the brake chambers. When the air is released, the springs push the brake shoes against the drums, locking the wheels in place. This design keeps the vehicle from rolling if you park or if air pressure drops. The other options aren’t how the parking brake is normally engaged: manually pulling a lever isn’t the standard method, the emergency brake switch is meant for emergencies rather than regular parking, and turning off the engine does not engage the parking brake.