What feature must a parking brake possess regarding energy sources?

A parking brake, also known as an emergency brake, is a crucial component of a vehicle's safety system. It must possess the feature that allows it to remain applied regardless of any exhaustion of the vehicle's primary energy sources, such as the electrical system or hydraulic fluid. This capability ensures that the vehicle remains stationary when parked, regardless of the operational status of other systems.

The design of the parking brake is such that it functions independently from the vehicle's regular braking system, which may rely on power from electrical or hydraulic systems. In the event that these systems fail or become compromised, the parking brake must still be able to hold the vehicle in place, preventing it from rolling away.

This level of reliability is vital for driver and passenger safety because it ensures that even without power, the vehicle can be secured. The integrity of the parking brake in various conditions underscores its importance in vehicle design and regulatory safety standards.