Document ZJ9ogrgzVkbqjgGYp1Nm1wXQ8

NAPA AUTOMOTIVE CAREER TRAINING THE AUTOMOTIVE BRAKE SYSTEM The purpose of automotive brakes is to enable the related to automotive brakes, was not applied until driver of the car to stop it or slow it down. There is a the 1920's. The first car to use a hydraulic brake separate brake assembly in each of the four wheels system was the 1921 Dusenberg. In 1928, Chrysler and they stop the car by applying friction to the Corporation adopted and installed hydraulic brakes rotating wheels. It is like rubbing a stick against the on their cars. In 1934, General Motors equipped the rim of the wheels of a child's wagon. Oldsmobile with a hydraulic brake system. Within the next six years, all other car manufacturers followed Two types of brake systems are used in today's auto suit, Ford being the last to change in 1940. mobiles - the drum brake and the disc brake. Regard less of whether the car is equipped with drum brakes, disc brakes, or a combination of the two, they are controlled simultaneously by the driver through a hydraulic system that connects the brake pedal to each of the four wheel brakes. This hydraulic system also serves another function - it transfers the pressure placed on the brake pedal by the driver to each wheel. To make it easier for the driver to stop the car a power assist mechanism can be added to the brake system. When this is done the car is said to be equipped with power brakes. On the adjacent page is a diagram of a typical auto motive braking system. Principles of Hydraulics The word hydraulic as it is used in connection with the brake system refers to the use of a non-compressible liquid as a means of transmitting pressure applied at the brake pedal, through the brake lines to the brake shoes. Pressure exerted at any point upon a confined liquid is transmitted by the fluid equally in all directions. In this fashion, pressure applied by the master cylinder piston causes the hydraulic fluid to be distributed equally to the wheel cylinders. HYDRAULIC BRAKES History of Automotive Hydraulic Brakes In the 17th century, Blaise Pascal, French philos opher and mathematician, announced the principle of hydraulics; that a liquid in a closed vessel transmits pressure equally in all directions. This principle, as It is important to recognize that air and other gases are compressible. If air is allowed to enter a hydraulic brake system, it will be compressed when the brakes are applied. The force applied to the master cylinder will then be largely taken up in compressing the air. This leaves little pressure for applying the brakes and results in poor brake performance and a "spongy" pedal. 2