The suspension system is an integral part of any car. Among the systems that remain in operation throughout the entire lifetime of an automobile is the suspension system. Whether your vehicle stays in the garage or is on the road, some parts of the suspension will always be at work.
The suspension system wouldn’t be needed if we drove on a perfectly flat road, which we know is not always the case. Even newly-built highways have slight bumps that come into contact with your car wheels.
And this is where the suspension system comes in. The suspension system manages the impact of the bumps to the wheels by reducing the bounce and riding discomfort.
Below we discuss in detail the various parts and functions of the suspension. Pull up a chair and let’s get started.
What is a Car’s Suspension System?
It is the system that links the car's body to the wheel. The car suspension components consist of the tyres, shocks absorbers, springs, and rods (linkages). The interconnection of these components allows relative motion between the wheels and the car body.
Functions of the Suspension System
As you will find out, the suspension is a critical system that enhances a car’s road-handling capability and improves the overall quality of the ride.
Also, it ensures maximum contact between the road and the wheels, which is essential because the tyres provide the surface area upon which the ground forces act. More crucially, it ensures maximum friction between the tyre and the road. These combined actions result in steering stability as well as comfort to the car passenger.
It also has a role in ensuring that little or no damage or wear comes to the car or its cargo. It performs this function by reducing the impact of the forces from bumpy terrains to the vehicle.
The suspension system also ensures that your car is maintained at the right ride height.
Parts and their Functions
The modern suspension system comes in various types, and each type consists of many pieces and structures. The specific design of each type enables them to perform the same purpose in different ways. Below we discuss the common parts and their functions.
The suspension system is essentially a connection of springs and dampers. It also carries parts such as bushings, linkages, arms & joints, axle carriers, and many others.
While every part of the system has a function, some do a little bit more than the others. These performance-defining components are springs, anti-sway bars, and shock absorbers. We will, therefore, start with them.
1. Springs
The springs absorb the shock forces when your wheels go over bumpy surfaces or potholes. Some car models make use of metal rods rather than springs, but they all accomplish the same task.
Their work is to ensure that you and the other passengers don’t feel the effect of the impact. Springing systems take many designs, but the common ones are:
Coil springs – Of all the types, this is the most common. It consists of heavy-duty torsional coils on the axis. They absorb the impact through compression and resultant expansion.
Leaf springs – For the leaf springs, metals called ‘leaves’ are stacked upon each other. The stacking ensures they work as a single unit.
Torsion bars – Steel bars can twist to a certain degree resulting in a coil-spring-like reaction, and torsion bars make use of this property. Anchored onto the ends of these bars are the vehicle frame and wishbone. The wishbone moves perpendicularly relative to the torsion bar. When you hit a bump while driving, vertical motion is generated. It is transferred to the wishbone, which is then passed on to the torsion bars via levering action. The torsion bars react by twisting along their axis, and this reaction provides the spring force.
Air springs – Air springs use a cylindrical air chamber, which is located between the wheels and the body. The compressive quality of air absorbs any impact from the wheels.
Another vital concept to understand is how sprung and unsprung mass differ from each other. Sprung mass refers to the vehicle weight supported by the springs in the suspension. On the other hand, unsprung mass refers to the load between the springs and the road.
2. Shock Absorbers
You can think of a shock absorber as an oil pump positioned in between the car frame and the wheels. One end of the shock absorber attaches to the frame, while the other end is attached to the axle just close to the wheel.
Shock absorbers work side by side with the springs to reduce the shock force. The shock absorbers support the springs and thereby control the motion of the springs. They lower the magnitude of the unwanted spring motion. This helps eliminate the bouncing of your car when you go over a bump or pothole.
Think of shock absorbers as snubbers. Shock absorbers are particularly useful in dampening. They contain highly-viscous oil that helps them perform their function. The oil dissipates heat resulting from the kinetic energy of the suspension’s movement. While the presence of oil is necessary, it also poses a problem. Oil leaks could cause problems in the system.
Types of Shock Absorbers
Shock absorbers can be any of the following:
- Telescopic – applied in both front and rear suspensions
- Strut type
- Spring seat shocks – combines both telescopic and strut features
3. Strut
The strut, much like a shock absorber, is crucial in dampening. In addition to dampening functions, struts give support for the car suspension. This difference is what distinguishes struts from shock absorbers. Shock absorbers don't provide structural support. Struts and shock absorbers are both critical and, as such, need proper maintenance.
4. Anti-sway Bars
Anti-sway bars, sometimes called anti-roll bars, are metal rods joining the suspension sides together. They run along the entire axle, providing stability when the car is moving. If the suspension of one wheel has a movement, it is the role of the anti-sway bars to ensure that the motion action is transferred to the other wheel.
The result is a level ride. The bars get their name from their function: reducing sway. Similarly, the term anti-roll is obtained from their role in combating roll, especially when you are cornering.
Anti-sway bars are standard equipment in any car today.
5. Rods
Rods are sometimes known as linkages. As the latter name suggests, they link different components and structures that make up the suspension system. They are built to be very durable, often lasting the lifetime of your car.
However, collisions could bring damage to these rods.
6. Joints, bushings, and bearings
The collective function of these components is to facilitate the connection of the system’s components by the linkages. Bushings and bearings facilitate the twisting and sliding action.
Bushings made from rubber have a higher wear rate. The joints also can loosen over time hence need regular maintenance.
Most of the minor problems of suspension systems are associated with joints, bushings, or bearings. Check out this article to find out about the parts of the suspension system that are prone to fail.
7. Tyres
Most people fail to consider the tyre as a part of the suspension system. Unlike most suspension system components, the tyre is an external part.
The tyres make contact with the road surface. Of all suspension system parts, tyres suffer the most wear and tear. They provide a surface where the ground forces can act on the car body. Driving on rough terrain, braking, and cornering put the tyres through most of the impact.
8. Steering System
Although the steering wheel and system at large is not a direct part of the suspension system, it is just as important. In addition to turning the wheels, the steering system controls linkages, joints, and even tie rods.
9. Frame
The suspension system, even with all the components mentioned above, remains incomplete without the frame.
The frame forms the skeleton onto which the weight of the car and its load is supported. It also offers a certain degree of support to the engine. Note that other suspension structures also provide support to the vehicle.
We have another article covering the various types of suspension systems and how they differ from each other. For suspension replacement parts, visit our website and find the most reliable auto parts sellers in Australia and the latest updates on the auto industry!
Sam O.