The brake system works with the help of a special type of oil which we call brake fluid. It is a special type of hydraulic oil which will not freeze in cold and will not boil at very high temperatures . With the brake line, the wheel pushes into the cylinder and from there the brake pad or needle presses the brake disc or brake drum attached to the wheel and stops the vehicle. Many cars today use four-wheel disc brakes, before the front wheel disc brakes and the rear wheel drum brakes were used, as in the diagram above.