What is the purpose of a brake pipe?

A brake pipe is a hollow tube that carries brake fluid from the master cylinder to the wheel cylinders or calipers in a hydraulic braking system. The purpose of the brake pipe is to allow the driver's foot pressure applied to the master cylinder to be transmitted to the wheel cylinders or calipers, so that the brake shoes or pads can create friction against the brake discs or drums and slow the vehicle down. The brake pipe is typically made of metal, such as steel or copper, and is designed to be strong enough to withstand the pressure of the brake fluid and the vibration caused by the vehicle's motion.