The History of Struts
The strut, also called the MacPherson strut, uses a coil spring and shock together, to function as independent suspension. Most coil springs are situated between the spindle and the top of the strut tower. The strut also incorporated torsion bars later in its design, and there have been modifications and variations to the MacPherson type strut from its conceptual beginnings, depending on the preference of the manufacturer. Double-wishbone suspension is a direct type and style derived from the original strut design. The history of the strut begins with Earle MacPherson who was born in Highland Park, Chicago in 1891.
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Earle MacPherson Beginnings
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Earel MacPherson first began work for the Chalmers Motor Company in 1915 and served in Europe during World War 1, where he apprenticed as an engine mechanic in the Army Signal Corps, headed by the Aviation Section. After the war he settled in Detroit and worked for Liberty Motor Company, which was bought out by Columbia Motors in 1923. His engineering and mechanical career at Columbia spanned a decade before he was hired by General Motors in 1934 as an assistant in the engineering department, headed by vice president. In one year he attained the position of chief design engineer for Chevrolet.
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A Guiding Force for the Strut Design
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MacPherson became the new engineer of the Chevrolet Cadet in 1945. It was intended that the Cadet, a revolutionary light, uni-body car, would appeal to the postwar car market. MacPherson had complete engineering control over the Cadet, including the suspension, and he desired to concoct the most cost-effective and practical independent suspension for it, to increase comfort, ride and maneuverability. He filed for a patent on his design in March 1947, and the patent was later approved in 1953. Unfortunately, General Motors cancelled the production plans for the Cadet, but by this time MacPherson had a solid grasp on his strut design and needed an active sponsor to produce it.
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A Sponsor Arrives
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The chief engineer, Harold Youngren, offered MacPherson a position as an executive engineer at the Ford Motor Company. MacPherson left Chevrolet and joined the Ford production team in 1947. Although MacPherson's strut design was not quite suited to Ford's large body-on-frame cars, the design found its first applications on Ford's smaller European models, including the Zephyr and Consul from the Britain plant, the Ford Vedette from France and the German-made Taunus.
The Strut Takes Hold of the Industry
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Since MacPherson held the design patent on his strut, many manufacturers were wary about using it because of the royalty costs. Ford's French subsidiary, Simca, adapted the strut design in 1954 and manufactured the Vedette until 1961. Porche followed suit in 1963, for its 911, with a modified torsion bar design, and Volkswagen started using the struts toward the end of 1960. The industry, which had kept its collective eye on the suspension design, finally adapted and produced the struts as soon as MacPherson's patent expired. The struts worked well on the numerous front-wheel-drive compact cars that started to proliferate and find a market share.
Strut Applications and the Future
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MacPherson had always desired his design to function on all four wheels, but for many years cost issues associated with additional rear strut suspension made it prohibitive, except for some of the very high-end performance cars, like Colin Chapman's Formula Two Lotus racers and Elite production cars. Other sports car manufacturers slowly followed suit. Ironically Ford Motor Company did not adopt MacPherson's struts for their domestic line until 1970, even though they had caught on well in Europe. Although MacPherson did not invent the suspension ball joint, he took the credit for applying ball joints to his strut design, and it became universal by the late 1960s.
The Strut Legacy
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Virtually any derivative form of the independent strut suspension design today can be linked back to Earle MacPherson's engineering concept and production efforts. Many vehicles today have four-wheel strut suspension, which is a vast improvement over the solid axle designs manufactured decades ago.
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