A grade of what percent is used to test the parking brake on an apparatus?

The correct grade used to test the parking brake on an apparatus is indeed 20%. This grade is significant because it represents a steep enough incline to effectively challenge the parking brake's ability to hold the vehicle in place. The requirement ensures that the parking brake is not only functional but also reliable under conditions it might face in real-world scenarios, such as on a slope.

Testing on a 20% grade simulates practical situations where the apparatus may be parked on an incline, which is common in emergency response situations, especially in urban environments. If the parking brake can securely hold the apparatus at this slope without rolling or shifting, it confirms that the system is performing as required, ensuring safety for both personnel and the equipment.

This standard is an accepted practice in many fire service operations and training programs, emphasizing the importance of maintaining rigorous safety checks on vehicle systems. Understanding these testing protocols contributes to the overall competency of driver/operators in managing their emergency vehicles.