<P> An anti-roll bar (roll bar, anti-sway bar, sway bar, stabilizer bar) is a part of many automobile suspensions that helps reduce the body roll of a vehicle during fast cornering or over road irregularities . It connects opposite (left / right) wheels together through short lever arms linked by a torsion spring . A sway bar increases the suspension's roll stiffness--its resistance to roll in turns, independent of its spring rate in the vertical direction . The first stabilizer bar patent was awarded to Canadian inventor Stephen Coleman of Fredericton, New Brunswick on April 22, 1919 . </P> <P> Anti-roll bars were unusual on pre-war cars due to the generally much stiffer suspension and acceptance of body roll . From the 1950s on, however, production cars were more commonly fitted with anti-roll bars, especially those vehicles with softer coil spring suspension . </P>

What is the sway bar on a car