A Show Stopping Invention. The History of Brakes
Brakes have been refined and improved ever since their invention. The increases in traveling speeds as well as the growing weights of cars have made these improvements essential. The faster a car goes and the heavier it is, the harder it is to stop. An effective braking system is needed to accomplish this task. Today's cars often use a combination of disc brakes and drum brakes. Disc brakes are usually located on the front two wheels and drum brakes on the back two wheels. Detroit is searching for even better engineered braking systems that will allow automobiles to decelerate in a shorter distance, while still allowing drivers to maintain control of their car.
All cars need a brake system; therefore it has been present in the automobile since its invention. However, the technology of the components and the design of the brake system have evolved throughout the years.
In the early days of the automobile, drum brakes were the standard. Drum brakes offered several advantages over other types of brakes. One of these was that the drum could keep out water and dust, materials that could damage disc brakes which were out in the open. The other, more important advantage was that drum brakes required drivers to apply less pressure on the pedal as compared to disc brakes. This was especially important in the days before hydraulic and power brake systems, both of which decreased the amount of pedal pressure needed.
The next major advancement in brake technology came in 1918 with the invention of four-wheel hydraulic brake systems by Malcolm Loughead. It is interesting to note that Loughead was a member of the Lockheed family, a company known better for producing airplanes. The hydraulic brake system replaced the mechanical brake system that was in use at this time. The mechanical system had numerous disadvantages. It made it difficult to brake all the wheels evenly, often causing a loss of control. In addition, it required drivers to exert tremendous amounts of force on the brake pedal to slow the car. The hydraulic brake system multiplied the force that was applied to the brake, lessening the amount of force needed to be applied to the brake pedal by the driver. This system was first used in the 1918 Duesenberg. It's advantages quickly caught on and by 1929, four wheel hydraulic braking systems were standard equipment on most higher priced cars. It took a few more years for the feature to become common on lower price cars.
As the speed of automobiles and their weight increased, better braking systems were required. The main problem with drum brakes is that the heat is not efficiently disbursed. The heat that is produced inside the drum does not escape easily since the drum prevents wind from drawing it away. However, disc brakes were open to the passing wind. This allowed the heat to be carried away which increased the efficiency of the brake. It is interesting to note that disc brakes were first used in 1902. However, their use was limited up until the 1950's since their efficiency was not required and they required more pedal pressure to operate. The reason for the higher pedal pressure is that disc brakes have no self-servo effect or no self-energizing capacity that the drum brakes have. The self-servo effect is caused by the forward motion of the car. This forward motion helps pull the brake shoe into contact with the drum. This helped lower the required pedal pressure. Now that their efficiency was needed and the hydraulic brake system multiplied the force applied to the brake pedal, disc brakes seemed to be the better alternative. Chrysler was the first to widely introduce the disc brake in its cars in the early 1950's. The system did not have much success. It seemed that the brake pressure required of the driver was still a little to great for the system to gain widespread consumer acceptance and therefore it was dropped. It finally took the failing automaker Studebaker to reintroduce the system in 1964. This time it saw much more success and in a few years, disc brakes were common on most new cars.
One of the reasons that disc brakes were a success with the Studebaker and not the Chrysler was due to the development of the power braking system. Power brakes became common in the 1950's, after Chrysler had developed and dropped its disc brake program. The system assisted the movement of the piston in the master cylinder which meant that the driver needed to apply less peddle pressure to get the same braking effectiveness. Therefore, since ease of braking was no longer an issue, the adoption of the more efficient disc brake became widespread.
Another development in braking systems came with anti-lock or anti-skid braking. With conventional braking systems, when the brakes are applied with enough pressure, the wheels will lock up. This results in a loss of steering effectiveness which may cause a loss of control. With anti-lock braking, the wheels do not lock up, allowing the driver to continue steering. Anti-lock brakes are not a new technology. They had been used in large aircraft since the 1950's and the British had used them in race cars in the 1960's. The first automaker to use this technology in its cars was Ford in 1969. It placed anti-lock brakes in the luxury Thunderbird and Continental Mark III. Today, anti-lock brakes are common on many new cars.
About the Author: Vance Talmadge is a mechanic with 20 years of experience in the Redondo Beach Brake and Tune industry. He has experience with every brake and brake system that is available on every car that is manufactured today.