Why is the hand brake primarily installed in cars?

The hand brake, also known as the parking brake or emergency brake, is primarily installed in vehicles to fulfill legal requirements regarding braking systems. Most automotive regulations mandate that a vehicle must have two independent braking systems to ensure safety. The hand brake acts as a backup to the primary braking system, providing an additional layer of security in case the main brakes fail. Its activation is usually independent of the foot brake and is designed to firmly hold the vehicle in place, particularly when parked on an incline.

Operational adjustments during driving, improving fuel efficiency, or assisting in steering are not the primary functions of the hand brake. Those aspects are served by other vehicle systems and components. For instance, operational adjustments while driving are managed through the regular braking system controlled by the foot pedal, while steering is managed by the steering system. Fuel efficiency is influenced by various factors such as engine performance and vehicle maintenance, but not by the hand brake itself.