What must the system be to hold the parking brake in the applied position?

The requirement for the parking brake system is that it must be able to hold the vehicle securely in place when engaged, regardless of other forces acting on the vehicle. For this reason, the system must utilize energy types beyond just fluid or electric, which can be influenced by other operational factors. This means that reliance solely on hydraulic or mechanical systems, which may be affected by failure or loss of energy (like leaks or electrical issues), is not sufficient for safety.

A parking brake that employs a method such as a spring-based mechanical system can better maintain its hold in the applied position, ensuring that it remains effective regardless of the condition of the hydraulic or electric systems. By using energy types other than fluid or electric, the system can provide redundancy and a reliable means of ensuring that the parking brake functions effectively under varying circumstances. This ensures that the vehicle remains stationary when necessary, highlighting the importance of a robust parking brake system for safety.