Suspension System

Syed Ashraf Ali Shah Rizvi

The purpose of the complete suspension system is to isolate the vehicle body from road shocks and vibrations which would otherwise be transferred to the passengers and load. It must also keep the tires in contact with the road, regardless of road surface.

Solid and Independent Suspension Solid, or beam, axles connect the wheels on each side of the vehicle. This means the

movement of a wheel on one side of the vehicle is transferred to the wheel on the other side.

With independent suspension, the wheels can move independently of each other, which reduces body movement. This prevents the other wheel being affected by movement of the wheel on the opposite side, and this reduces body movement.

When a wheel strikes a bump, there is a reaction force, and energy is transferred to the spring which makes it oscillate. Oscillations left uncontrolled can cause loss of traction between the wheel and the road surface.

Shock absorbers dampen spring oscillations by forcing oil through small holes. The oil heats up, as it absorbs the energy of the motion. This heat is then transferred through the body of the shock absorber to the air.

When a vehicle hits an obstruction, the size of the reaction force depends on how much unsprang mass is at each wheel assembly.

Sprung mass refers to those parts of the vehicle supported on the springs. This includes the body, the frame, the engine, and associated parts.

Unsprang mass includes the wheels, tires, brake assemblies, and suspension parts not supported by the springs.

Vehicle ride and handling is improved by keeping unsprang mass as low as possible. Wheel and brake units that are small and light follow the road contours without a large effect on the rest of the vehicle.

Modern Suspension Systems being currently used

Air suspension :- is a type of vehicle suspension powered by an electric or engine-driven air pump or compressor. This compressor pumps the air into a flexible bellows, usually made from textile-reinforced rubber. The air pressure inflates the bellows, and raises the chassis from the axle. The purpose of air suspension is to provide a smooth, constant ride quality, but in some cases is used for sports suspension. Modern electronically controlled systems in automobiles and light trucks almost always feature self- levelling along with raising and lowering functions. Although traditionally called air bags or air bellows, the correct term is air spring.

Magnetorheological fluid :-A magnetorheological fluid (MR fluid) is a type of smart fluid in a carrier fluid, usually a type of oil. When subjected to a magnetic field, the fluid greatly increases its apparent viscosity, to the point of becoming a viscoelastic solid (MagneRide)

Audi’s Latest Researched Suspension Systems

Dynamic Ride Control:- Audi currently offers Dynamic Ride Control technology in the RS 5, among other models. DRC is a purely mechanical, and thus fully lag-free, system for reducing body roll and pitch around the transverse and longitudinal axes.

Audi magnetic ride:-Audi magnetic ride is a suspension technology employed in the A3, TT and R8 families. This system continually adapts the function of the shock absorbers to the road profile and the driver’s style.

A synthetic hydrocarbon oil containing tiny magnetic particles between 3 and 10 thousandths of a millimetre in diameter – one tenth the thickness of a human hair – circulates in the shock absorber pistons. When voltage is applied to a coil integrated in the damper, a magnetic field is produced and the particles realign. They orient themselves crosswise with respect to the direction of oil flow in the piston channels, obstructing its flow. The process is completed in a few milliseconds.

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Audi’s adaptive air Suspension

Audi’s Magnetic Ride system