What is the required performance of the parking brake when tested on a 20% grade?

The required performance of the parking brake on a 20% grade is that it should hold the vehicle in place. This standard is crucial for maintaining safety and preventing the vehicle from rolling backward or forward on a steep incline. A well-functioning parking brake is designed to provide sufficient resistance to hold a vehicle stationary under various conditions, including on gradients. Therefore, it must effectively secure the vehicle when parked, demonstrating that it meets the necessary safety requirements set for vehicle inspections.

If a vehicle were to slip slightly or fail completely, it would indicate that the parking brake is not functioning as intended, posing a safety risk. Similarly, a parking brake that only works in one direction would not provide reliable performance in every situation where the vehicle might be parked on inclines. Thus, the ability to hold the vehicle in place is the benchmark for effective parking brake performance on steep grades.