Electronic Chassis Control

Automotive Industries,  August, 1999  by Don Sherman

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Rubber elements were first used on road vehicles more than 150 years ago. One of Preston Tuckers post-WWII development headaches was a Torsilastic spring -- shear-loaded rubber molded directly to each trailing arm.

Pneumatic springs were all the rage immediately before and after the turn of the century. Lincoln and several GM divisions toyed with air suspension in the 1950s with modest success. Today, air-assist springs are commonly used for load leveling.

European makers gamely tried combination approaches: Citroen's 1955 DS-19 rode on suspension spheres containing hydraulic oil and nitrogen gas. British Leyland used oil and rubber (Hydralastic) then oil and gas (Hydragas) systems.

Various interconnection schemes have been employed to balance chassis loads. Citroen's 1949 2CV tied a front wheel to the adjoining rear wheel by means of spring-loaded links. In 1955, Packard coupled front and rear suspension systems with torsion bars.

Friction dampers were first used before the turn of the century. The telescopic hydraulic damper was invented in 1901. Nissan reinvented driver-adjustable shock absorbers in the 1984 300ZX.

In the 1960s, after decades of research, Westinghouse Electric published four technical papers extolling the benefits of "active" suspension -- a power source helping to counteract disturbances caused by suspension motion and inertia forces. GM, Lotus and Volvo continued this quest during the 1980s. In 1991, Infiniti was the first to offer a semi-active suspension system as optional equipment on its Q45.

For the 2000 model year, electronic chassis control systems are offered on a growing number of luxury sedans. Among them, BMW's third-generation Dynamic Stability Control and Ford's optional AdvanceTrac system on the Lincoln LS control vehicle dyamic stability using brake force distribution, applied when needed to any wheel. They employ a yaw-rate sensor and the car's ABS and traction control. And Honda's Acura division also enters the fray.

-- DS

COPYRIGHT 1999 Cahners Publishing Company
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