The History of Power Hydraulic Brakes
Early automobile brakes consisted of steel bands that tightened around a drum installed on the rear axle. These brakes were a carryover from...
Early automobile brakes consisted of steel bands that tightened around a drum installed on the rear axle. These brakes were a carryover from braking systems used on horse-driven carriages. As automobile speeds approached 80 mph, early systems became inadequate. In 1918, an inventor named Malcolm Loughead discovered how to use hydraulics in automotive braking systems. Loughead's name was later changed to Lockheed, and he co-founded the Lockheed Aircraft Corporation in 1932.
Drum Brakes
Development of internal drum braking systems preceded development of hydraulic braking systems. A Frenchman named Louis Renault is credited with development of the internal drum braking system in 1902. Placement of the brake shoes inside the brake drum eliminated the destructive action of water and dirt on brake parts. Early internal drum brake systems employed mechanical systems to force brake shoes against the brake drum. The primary drawback of using mechanical systems to apply brakes is the cumbersome routing of brake linkage to all four wheels.
First Application
Malcolm Loughead figured out how to use metal tubing, hydraulic cylinders and hydraulic pistons to apply fluid pressure that forced brake shoes against the internal surface of brake drums. This technological advance was quickly put to use when the first hydraulic brake systems were installed on 1918 Duesenberg automobiles. By 1921, the Duesenberg Model A featured four-wheel hydraulic drum brakes. The development of hydraulic brakes allowed Duesenberg to build production cars with speeds up to 130 mph.
General Acceptance
By 1931, most of the major American automobile manufacturers were building cars with the new hydraulic brake systems. Ford Motor Company continued with mechanical brake systems until 1939, when the company finally began using hydraulic brakes. Since hydraulic brake tubing could be routed more efficiently than mechanical linkage or cable systems, automobile manufacturers were able to adopt much sleeker body designs. The combination of internal brake shoes, hydraulic brake systems and the development of vacuum brake boosters made it safer to drive cars at faster speeds.
Latest Developments
Vacuum brake booster systems first appeared on 1928 Pierce-Arrow automobiles. These systems use vacuum from the engine's intake manifold to ease the physical effort needed to apply the brakes. General Motors began switching to electric brake boosters in 1985. Electric power assist systems, along with anti-lock brake systems, are now considered essential elements of a complete hydraulic braking system. Modern four-wheel disc brake systems use on-board computers to ensure the precise amount of hydraulic pressure reaches each wheel to aid in vehicle stability.
