Suspension systems are not only meant for comfortable rides but they also serve one primitive purpose without which driving safe is not possible. Suspension system do the job of keeping the wheels in contact with the ground all the time. Be it a car or a two-wheeler, without all wheels in contact, it is almost impossible to steer a vehicle properly. Over the years, various manufacturers have come up with different approaches to suspensions. Luxury cars use high quality suspension systems that provides the user a comfortable ride whereas a sports car is engineered in such a way that it can corner at high speeds.The different suspension systems that we will be discussing are Rigid axle and Independent suspension systems. We will also see the use of Springs, Shock absorbers and Sway bars in suspension.
RIGID AXLE SUSPENSION SYSTEMS:
Rigid axle is the first type of suspension widely used by manufacturers. It is also called the solid axle or live axle. This suspension utilizes a rigid solid beam for connecting the two wheels. The manufacturing cost of a rigid axle is low and for the cost the system provides good wheel travel which is highly desirable in heavy load carrying vehicles. This system does not provide great ride quality but it is cheap. Hence popular in trucks. The disadvantage is that if one of the wheels encounters a bump or a pot hole, the other wheel gets affected adversely.
JEEP WRANGLER uses this system on both the front and rear sides.
As the name suggests, all the wheels move independent of each other in the vehicle. That is if one wheel encounters a bump, the other three wheels are not affected by it. The independent suspension systems offer a comfortable ride but at the cost of reduced wheel travel and complex mechanisms. Consequently, this suspension system is costlier than the rigid axle system. The two commonly used independent suspension systems are Macpherson Struts and Double Wishbone Suspension. These offer good cornering capabilities to the vehicle and hence they are used in Ford fusion, Lexus LS and the Subaru Impreza WRX.
Be it rigid or independent suspension systems, manufacturers have found various ways to incorporate several components like springs, shock absorbers and sway bars to improve the suspension.
Springs can be mounted on rigid or independent systems and they provide a cushioning effect to the vehicle by either compressing or expanding. They are capable of recovering after a compression or expansion. Some vehicles like trucks make use of similar mechanisms like air suspension where a chamber of air is compressed to achieve suspension effect.
Shock absorber units are used along with springs and they aid in damping the shocks produced by sudden jerks or bad road conditions. Shock absorbers are generally metal tubes filled with highly viscous liquids such as oil or sometimes air or even a combination of both. Strut is a type of shock absorber that includes both a suspension system and a shock absorber. Nowadays advanced shock absorber systems are used in cars like Audi R8 and Ferrari 599 where a special liquid whose shock absorbing capability can be varied by passing electric current is used. This way the suspension can be adjusted in real time and the riding comfort can be enhanced drastically.
Sway bars are called stabilizer bars and the function of these bars is to limit the roll of a vehicle. It is simply a steel bar connecting the left and right ends of a car, the thickness of which determines how much the body can roll. Now there are electrically controlled sway bars that vary their actions automatically. BMW 550i has this feature.