Automotive Glossary

ACTIVE SUSPENSION SYSTEM

ACTIVE SUSPENSION SYSTEM

What it is: Active suspension systems move each wheel up and down to control body motion in response to road abnormalities. The system responds to inputs from the road and the driver. With an active suspension, a vehicle can simultaneously provide the smooth ride of a soft suspension along with superior handling associated with a firm suspension. How it works: Most active suspension systems use a high-pressure pump with hydraulic cylinders at each wheel to position the wheels with respect to the vehicle. Up and down motion of the wheels is actuated by electronically controlled valves. Other alternatives to power active suspension systems include electric motors or electromagnets. In any system, sensors at each wheel determine vertical wheel position and the force of the road acting on the wheel. Some systems use "road preview" sensors (radar or laser) to provide information about road abnormalities before the front wheels reach them. Accelerometers tell the computer when the vehicle is accelerating, braking or cornering. The computer uses complex algorithms to continuously process information and decide the position of each wheel. Coil springs can be used at each wheel to avoid "bottoming out" of the suspension in case of system failure; they also can reduce the power required to support the sprung weight of the vehicle. Customer benefit: Outstanding ride and handling, even on rough roads.

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