Sway Bar - Active Systems

Active Systems

Some high-priced cars, such as the Range Rover Sport and BMW 7-series, have begun to use "active" anti-roll bars that can be proportionally controlled automatically by a suspension-control computer, reducing body lean in turns while improving rough-road ride quality. The first to use this was the Citroen Xantia Activa, a medium sized sedan sold in Europe. The Activa system featured an anti-roll bar that could be stiffened under the command of the suspension ECU during hard cornering. The car rolled at any time at most 2 degrees. Mercedes S-class ABC system uses another approach: the computer uses sensors to detect lateral load, lateral force, and height difference in the suspension strut, then uses hydraulic pressure to raise or lower the spring to counter roll. This system removes the anti-roll bar. Most active roll control systems allow a small degree of roll to give a more natural feel.