Car Suspension: How Does it Work? Parts and Types Explained

What is a Car Suspension?

In simple words, car suspension is a component of a car that cushions the forces that a vehicle goes through while driving on the road.

The suspension cushions the cabin from the external forces felt due to small stones/rocks on the road, bumps/speed breakers or small/big potholes. Apart from negating the external forces, a suspension is also responsible for the stable handling of a vehicle. Without a suspension system, it may be impossible to drive a car.

How Does a Car Suspension Work?

Now that you understand what suspension is, refer to the points below to understand how a car suspension works.

• A car suspension works on the principle of force dissipation.
   
• It involves converting the force into heat and thus negating the impact on the car’s body.
   
• The suspension system uses components such as springs, shock absorbers and struts to achieve the damping effect.

Sounds like a bumpy ride? Worry not; we will explain all these terms in detail in the following sections of this article.

Car Suspension Parts

Now that the suspension system is clear, we will take a look at car suspension parts. A suspension comprises several parts that work together to dampen the shocks. Below are the key components of a car suspension.

1. Spring

Spring is one of those parts which you may have come across in your day-to-day life. It is generally coiled up and elastic. The spring compresses or extends depending on the external force applied. The spring in the car suspension also works on the same principle. The following points will explain the working mechanism of a spring in a suspension system.

• The primary job of a car suspension spring is to store energy generated when the car drives over a bump, pothole, etc.
   
• The amount of energy stored by a spring depends on various factors such as material, length, coefficient of spring, etc.
   
• When you drive the car on a flat surface, the spring compresses due to the vehicle's weight.
   
• When you drive over a dip on the road, the spring extends and ensure that the tyres are in contact with the road surface.
   
• Similarly, when you drive over a bump, the spring compresses and keeps the tyres in contact with the road.
   
• There are two types of springs used in suspensions: coil springs and leaf springs.
   
• Coil springs are one of the most common springs, and you can see them on most cars.
   
• Leaf springs were used in older cars, and you can also find them on heavy-duty vehicles such as trucks with solid axles.
   
• A leaf spring can store more energy than a coil spring. Hence, heavy-duty vehicles use leaf springs.

However, a spring alone cannot provide a smooth driving experience because springs are only good for storing energy and not so good at dissipating energy. With only springs the car will still bounce until the energy is dissipated. Dampers/shock absorbers are the solution to this problem.

2. Dampers/Shock Absorbers

A damper or shock absorber is a fluid/gas-filled reservoir encased within a tube. It is fitted between the car’s frame and wheels. The upper mount of the shock absorber is connected to the frame. The lower mount is attached to the axle. The damper’s upper mount is connected to a piston rod attached to the piston with tiny holes. The piston sits in a tube that is filled with hydraulic fluid. 

Go through the points below to understand the working mechanism of a damper.

• When the wheels go over a bump/dip on the road, the spring extends/compresses.
   
• The energy stored in the spring is transferred to the damper via the upper mount.
   
• The energy is dissipated to the piston rod and then into the piston.
   
• Due to the energy, the piston moves through the oil. The oil is then forced through the piston holes and is channelled into a separate chamber.
   
• The manufacturer can alter the resistance of the shock absorber by varying the size of the holes in the piston. It is also called the dampening rate. The higher the damping rate, the softer the ride.

Similar to springs, there are different types of shock absorbers, such as single-tube, twin-tube, gas-filled and exterior reservoir dampers. However, the working principle of the shock absorbers remains the same.

3. Struts

The struts are not an individual component of a suspension system. Instead, they are the structural components comprising the spring and shock absorber. In simple words, a damper wrapped with a coil spring is called a strut. A strut integrates the different suspension components into one compact assembly.

4. Anti-Roll Bar

The anti-roll bar is responsible for preventing the car’s body from rolling when driving on corners/road irregularities. It is a metal rod that connects the left and right sides of the suspension. The following points explain how the anti-roll bar works in conjunction with the suspension system.

• When the suspension moves up/down (left or right wheel) due to road irregularities, the anti-roll bar transfers the energy to the other wheel (left or right side).
   
• It results in a level ride and reduces the possibility of the car rolling while going through a corner.
   
• Almost all cars are fitted with an anti-roll bar as standard.

Types of Car Suspension

The technology in the automotive industry is evolving with each passing day, and it has resulted in car manufacturers coming up with different types of car suspensions. Let's glance through some of the most common types of suspension systems used in cars.

Car suspensions are broadly classified into two types: non-independent and independent suspensions. Below are the details of each suspension system.

1. Non-Independent Suspension

It is a type of car suspension wherein a rigid axle connects the left and right wheels. In other words, it is a solid bar held in place with the help of leaf springs and shock absorbers.

This type of suspension can be seen on trucks and some SUVs as well. However, non-independent suspensions are not used in modern cars.

2. Leaf Spring Suspension

It is one of the types of non-independent suspension in cars, and the leaf springs are attached to a solid axle. This type of arrangement is mainly used in heavy vehicles such as trucks and buses.

A leaf spring is made out of several plates that are held together by rebound clips. The size of plates keeps getting shorter, and the most extended plate is called a master leaf. The advantages of this type of suspension are that it is inexpensive to manufacture, and it can withstand a lot of weight. That's the reason it is widely used in heavy vehicles.

3. Trailing Arm Suspension

A leaf spring alone cannot stop the side-to-side and forward and backwards movement of a vehicle. So, control arms are fitted, and they are called trailing control arms. They are simple in construction and attached to the axle and the vehicle’s chassis.

One can easily adjust the arms without removing them from the vehicle. One of the advantages of the trailing arm suspension is that it negates the external forces felt by the axle. Similar to leaf springs, they are also strong and durable.

4. Independent Suspension

As the name suggests, in this type of suspension, the left and right wheels move independently. There are several types of independent suspension that use different arrangements of springs and shock absorbers. This suspension is more complex in construction but offers a better dampening effect.

5. MacPherson Strut Suspension

It is one of the most common types of suspension. The MacPherson strut suspension is compact, lightweight, and the car suspension price is also on the lower side due to its simple construction. Below are the details of the MacPherson strut suspension.

• It is a combination of a coil spring and a shock absorber.
   
• It takes up less space due to its compact design and allows for more room for the fitment of other components.
   
• It is also lightweight, hence reducing the overall weight of the car.
   
• Not suitable for sports cars with low ride height due to the vertical assembly.
   
• Also, not ideal for cars with wider wheels as it requires more input on the steering wheel.

6. Double-Wishbone Suspension

It is a type of independent front suspension mainly used in high-end cars. Below are the details of the double-wishbone suspension.

• It uses two wishbone-shaped arms to hold the wheel in place.
   
• A wishbone has two mounting points, one for the frame and the other for the wheel.
   
• The suspension uses coil springs to absorb energy and dampers to dissipate the energy.
   
• Double-wishbone suspension is a lot more stable than other suspensions. It also results in improved dynamics.
   
• It is expensive due to its complex design and construction.
   
• The cost of repair/maintenance is high due to several components within the suspension system.

7. Multi-Link Suspension

It is the latest evolution of the double-wishbone suspension. The multi-link suspension uses three or more lateral arms and one or more longitudinal (vertical) arms. The advantage of this suspension is that the arms can be angled in any direction. It allows for a better balance between ride quality and handling. Generally, performance cars use this type of suspension.

8. Air Suspension

It is an advanced suspension system that is mainly used in luxury cars. In this type of suspension, the traditional coil spring is replaced by air springs. They are made out of tough rubber and inflated with air.

The air suspension uses an air compressor, sensors and electronic controls to fine-tune the system. You can adjust the suspension (ride height) depending on the roads and load on the vehicle. It provides excellent cushioning. However, it is expensive and thus only used in luxury cars.

Also, read: Air-bagged suspension system in cars

Pros and Cons of Each Suspension Type

Various car suspension systems have inherent advantages and disadvantages depending on comfort, handling, price, and suitability for terrain. The table below outlines a concise comparison of the advantages and disadvantages of every suspension type in order to facilitate your understanding of their actual performance.

Car Suspension Problems and How to Identify Them?

Now that you are aware of the basic working mechanism of a car suspension, you should also be mindful of the anomalies in a suspension. Suspension is a mechanical component that may fail over time. However, if you notice the problem early, you can save yourself from a catastrophic suspension failure. 

Below are some signs that suggest the suspension needs an inspection or repair work.

• If you start feeling every bump on the road or your car bounces due to road irregularities, the suspension needs a checkup.
   
• You can also conduct a ‘Bounce test’ to check the suspension. Press down on the front of the car with all your weight, bounce it a few times, and release. If the vehicle bounces more than three times, the suspension needs some pampering from a mechanic. You can repeat the same process for the rear suspension as well.
   
• If your car pulls to one side when cornering, the possibilities are that the shock absorbers are failing.
   
• The suspension may also have some issues if the car nose-dives (sudden compression of front suspension) when braking, rolls to the side while cornering or squats during normal acceleration.
   
• Lastly, examine the tyres. If the treads have worn out unevenly, the suspension is putting uneven pressure on the tyres. It is a sign that there is an issue with the suspension.

Also, read: Drum Brakes vs Disc Brakes

How to Maintain the Car Suspension System

You maintain your suspension system in proper condition through maintenance, which gives your vehicle a smooth, safe, and efficient ride. Be aware of the following while maintaining your suspension to keep it running:

• Check tyre pressure and wheel alignment regularly: Poor wheel alignment or underinflated tyres cause additional stress on the suspension.
   
• Slow driving over potholes and speed breakers: These may cause deterioration of springs, shocks and bushings.
   
• Don't overload the vehicle: Overloading subjects suspension components to unnecessary stress.
   
• Suspension inspection at the time of servicing: Have your mechanic check shocks, struts, mounts, and bushings.
   
• Replace worn-out parts in a timely fashion: Bushings, mounts, and dampers deteriorate with time. Have them replaced before causing further damage.
   
• Be on the lookout for strange noises: Clunks, creaks while in motion may signal suspension issues.
   
• Perform a 'bounce test' from time to time: When your vehicle bounces over two times when pushed, the suspension inspection time is now.

Best Suspension Cars in India

A suspension works best when it’s tuned to match the driving conditions. For instance, a vehicle used to drive on off-roads may require a soft suspension setup, while a car used on highways/paved roads may need a slightly stiffer suspension to improve handling. 

Here is a list of cars that come with the best suspension setup for the Indian roads:

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