Brakes

Drum Brakes

The drum brake, as it is now known, became all-dominant in the United States. In Europe, particularly in Great Britain, it had to share the stage with disc brakes. Disc brakes became more or less standard on European cars during the '50s, about 20 years before they were adopted by American manufacturers in 1973.

This is ironic, because the spot-type disc brake is an American invention. In 1898, Elmer Ambrose Sperry of Cleveland designed an electric car having front-wheel disc brakes.

He made a large disc integral with the hub on each wheel. Electromagnets were used to press smaller discs, lined with a friction material, against spots on the rotating disc to bring the wheel to a stop. Springs retracted the spot discs when current was interrupted.

Meanwhile in Great Britain, a patent was issued in 1902 to F. W. Lanchester for a nonelectric spot disc braking system that's similar in principle to what we have today. The biggest problem that Lanchester encountered was noise. Metal-to-metal contact between his copper linings and the metal disc caused an intense screech that sent chills through anyone within earshot.

The problem was solved in 1907 when Herbert Frood, another Englishman, came up with the idea of lining pads with asbestos. The new material was quickly adopted by car manufacturers on both drum and disc brakes. Asbestos linings also outlasted other friction materials by a wide margin. The 10,000-mile brake job had arrived.

As roads improved and cars began to be driven at high speeds, manufacturers recognized the need for even greater braking power. One solution to the problem became apparent during the Elgin road Race of 1915. A Duesenberg took the flats at 80 mph, then screeched to a virtual crawl to negotiate the hairpin curves. Duesenberg's secret for such magnificent braking power was to simply use an internal brake on each front wheel as well as each rear wheel.

In 1918, a young inventor named Malcolm Lougheed (who later changed the spelling of his name to Lockheed) applied hydraulics to braking. He used cylinders and tubes to transmit fluid pressure against brake shoes, pushing the shoes against the drums. In 1921, the first passenger car to be equipped with four-wheel hydraulic brakes appeared -- the Model A Duesenberg.

Carmakers as a group were not quick to adopt hydraulics. Ten years after the Model A Duesie, in 1931, only Chrysler, Dodge, Desoto, Plymouth, Auburn, Franklin, Reo, and Graham had hydraulic brakes. All the others still had cable-operated mechanical brakes. In fact, it was not until 1939 that Ford finally gave in, becoming the last major manufacturer to switch to hydraulic brakes.

The basic braking system we have today was pretty much in place by 1921, including a refinement some regard as contemporary -- power assist.

Air Brakes

Power assist, technically, dates back to 1903 when a car called the Tincher used air brakes. But the first car to be equipped with a vacuum-operated power booster similar to those we have today was the 1928 Pierce-Arrow. It used vacuum from the inlet manifold to reduce the physical effort needed to apply brakes. Vacuum boosters from then to now have similar designs.

The first widespread deviation from vacuum power assist came about in 1985. Some '85 GM cars use an electrically driven brake booster, which is smaller and lighter than the conventional vacuum booster, giving an all- hydraulic system. Some cars with antilock brakes also use all-hydraulic systems.

The first car to have self-adjusting brakes was the 1925 Cole. The prototype for today's systems appeared on the 1946 Studebaker. The mechanism by Wagner Electric Co., consisted of an adjusting wedge under the influence of a tension spring. As linings wore, a plug receded to move a pin and lever against the spring. This forced the adjusting wedge against brake shoes, which expanded to keep linings at a preset distance from the drums.

Anti-Skid Brakes - ABS
As for the antilock (antiskid) units now available in the U.S., they are hardly new. The first practical antiskid braking system, named Maxaret, was developed in 1958 by the Road Research Laboratories in Great Britain and was first applied to the Jensen FF sports sedan in 1966.

Three years later, in 1969, the Lincoln Continental Mark III was equipped with an Auto-Linear antilock unit developed by Kelsey-Hayes. Sensors on the rear wheels transmitted signals to a transistorized "computer" behind the glove box. The computer controlled a vacuum-operated valve on the rear brake line to modulate pressure to the rear brakes when the sensors told the computer that the brakes were locking.

Cost and some technical problems caused the shelving of this unit. But now, updated versions that give four-wheel skid control are offered on almost every car model, although initially they were available only on high-end cars like Lincoln and Mercedes, and a few European cars.

Computerized brakes notwithstanding, there is a piece of advice about using brakes that's as relevant today as it was in 1909 when it was first published in The American Cyclopedia of the Automobile:

"Good driving in traffic is shown by making the minimum use of brakes. The strain on passengers amounts to intense nervousness when the car is constantly driven so that the least alteration of direction or of pace on the part of any vehicle ahead results in the violent application of the brake."

And so it will always be.

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