What is a car Suspension System? | Suspension

What is a car Suspension System?

The suspension is the system of tires, tire air, springs, shock absorbers, and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which is at odds with each other.

The tuning of suspensions involves finding the right compromise. It is important for the suspension to keep the road wheel in contact with the road surface as much as possible because all the road or ground forces acting on the vehicle do so through the contact patches of the tires.

The suspension also protects the vehicle itself and any cargo or luggage from damage and wear. The design of front and rear suspension of a car may be different.

Why is your car,s suspension so important?

Your car’s suspension system is responsible for smoothing out the ride and keeping the car in control. Specifically, the suspension system maximizes the friction between the tires and the road to provide steering stability and good handling.

The suspension system also provides comfort for passengers to limiting the impact of particular road conditions to not only the car, but the passengers riding inside.

The suspension system is made up of several components, including the chassis, which holds the cab of the car. The springs support the vehicle weight and absorb and reduce excess energy from road shocks, along with the shock absorbers and struts. Finally, the anti-sway bar shifts the movement of the wheels and stabilizes the car.

Your car’s suspension system must be in good condition. Worn suspension components may reduce the stability of the vehicle and reduce driver control, as well as accelerate wear on other suspension system components. Replacing worn or inadequate shocks and struts will help maintain good ride control, as they:

  • Control spring and suspension movement
  • Provide consistent handling and braking
  • Prevent premature tire wear
  • Help keep the tires in contact with the road
  • Maintain dynamic wheel alignment
  • Control vehicle bounce, roll, sway, drive, and acceleration squat
  • Reduce wear on other vehicle systems
  • Promote even and balanced tire and brake wear
Car Suspension

How does a car suspension work?

A suspension works on the principle of force dissipation which involves converting force into heat thus removing the impact that force would have made. It uses springs, dampers, and struts to achieve this. A spring will hold the energy while a damper will convert it into heat.

The job of a car suspension is to maximize the friction between the tires and the road surface, to provide steering stability with good handling and to ensure the comfort of the passengers.

If a road were perfectly flat, with no irregularities, suspensions wouldn’t be necessary. But roads are far from flat. Even freshly paved highways have subtle imperfections that can interact with the wheels­ of a car.

It’s these imperfections that apply forces to the wheels. According to Newton’s laws of motion, all forces have both magnitude and direction. A bump in the road causes the wheel to move up and down perpendicular to the road surface.

The magnitude, of course, depends on whether the wheel is striking a giant bump or a tiny speck. Either way, the car wheel experiences a vertical acceleration as it passes over an imperfection.

Without an intervening structure, all of wheel’s vertical energy is transferred to the frame, which moves in the same direction. In such a situation, the wheels can lose contact with the road completely. Then, under the downward force of gravity, the wheels can slam back into the road surface.

What you need is a system that will absorb the energy of the vertically accelerated wheel, allowing the frame and body to ride undisturbed while the wheels follow bumps in the road.

The study of the forces at work on a moving car is called vehicle dynamics, and you need to understand some of these concepts in order to appreciate why a suspension is necessary in the first place.

Parts of Suspension System

Following are the Parts of Suspension:

  • Wheels and tires
  • Springs
  • Shock absorbers and struts
  • Linkages
  • Bushings, bearings, and joints
  • Steering system all types
  • Hydraulic power steering
  • Electric power steering

1. Wheels and tires

Tires aren’t always considered part of the suspension, but they’re arguably the most important component of it. It provides traction for acceleration, braking, and cornering, and absorbs small bumps.

Tires wear over time, and are subject to cuts and punctures from hitting sharp objects, and to slow or sudden leaks from impacts. On the other hand, wheels fail (from bending or cracking) much less often, usually only in response to hard impacts from accidents or hitting potholes.

2. Springs

Every car and truck today has some sort of mechanism to absorb large bumps, and this always includes some form of spring, a metal part that bends in response to force. (A few cars over the years, particular those made by Chrysler, have used torsion bars metal rods that absorb impacts by twisting instead of bending instead of coil or leaf springs, but these are all different forms of spring.)

Springs can sometimes break when the vehicle hits a bump very hard, and many will sag eventually (after many years), but in general these parts are much less prone to failure than most other suspension components.

3. Shock absorbers and struts

While springs absorb the bumps, shock absorbers (or, in cars that have them, struts, which are similar to shocks) dampen the motion of the springs after a bump, keeping the vehicle from bouncing excessively.

Shocks and struts are filled with a thick oil, and over time the oil can leak out, causing the shock or strut to fail. Impacts and accidents can also cause leakage or can damage delicate internal parts.

4. Linkages

Every suspension includes various rods and other connecting pieces that collectively keep the wheels where they’re supposed to be relative to the rest of the vehicle. Most of these linkages are solid metal parts that rarely fail except in major accidents.

However, sometimes linkages and associated bushings are sold together, and the failure of a bushing can necessitate replacing the whole assembly.

5. Bushings, bearings, and joints

Because most parts of any suspension must be movable, the various linkages are connected by flexible connections. These include bushings and bearings, which are connections that allow a small amount of twisting or sliding, often without needing lubrication, and joints, which in automotive applications often use a lubricant such as grease to allow for controlled movement.

Some suspension bushings are made of rubber, which can become brittle or break over time, leading to failure. Many joints tend to wear out, leading initially to looseness and eventually to failure. A couple of the most common culprits are tie rod ends, which are lubricated joints that connects certain steering linkage parts, ball joints, which are found in both the steering system and attached to the control arms, and the bushings that separate the control arms from the vehicle’s frame.

6. Steering system all types

Every steering systems contains numerous linkages, some joints such as the tie rod ends mentioned above, and some sort of steering box, the mechanical device that converts rotation of the steering wheel into movement of the car’s wheels.

In general, linkages aren’t very likely to fail, while components such as tie rod ends are. Steering boxes wear out eventually, with rack-and-pinion steering systems in vehicles equipped with hydraulic power steering being the most failure-prone.

7. Hydraulic power steering

Many vehicles are equipped with power steering. Of the two types of power steering, hydraulic systems (i.e., those that use a high-pressure fluid to help the driver turn the wheels) are more failure-prone. Fluid can leak from high-pressure lines, delicate valves occasionally wear out, the belt that drives the power steering pump can loosen or break, and eventually, the pump itself may fail.

8. Electric power steering

More and more power steering systems found in modern cars and trucks are electric, not hydraulic. Electric power steering systems include various sensors, wires, and actuators (motors), any of which can fail, but luckily such failures are less common than failures of hydraulic components.

Types of Suspension system

There are three basic types of suspension components: linkages, springs, and shock absorbers. The linkages are the bars and brackets that support the wheels, springs and shock absorbers. Springs cushion the vehicle by dampening shock loads from bumps and holes in the road.

Shock absorbers use hydraulic pistons and cylinders to cushion also the vehicle from shock loads. They also serve to dampen spring oscillations, thus bring the vehicle back to a neutral position soon after being shock loaded by a road obstruction. 

There are a number of various shaped links that are used for the different types of suspension systems. They vary from straight bars to forged, cast or stamped metal shapes that best fit to support the springs, shocks and wheels onto vehicle frames or body structures.

The simplest linkage is a straight bar that connects one wheel to the other on the opposite side of the vehicle. Others can be intricately shaped to connect springs, shock absorbers and wheels to vehicles as explained later.

2. Springs

There are three different spring types that are used in suspension systems: coil, leaf and torsion bar. Coil springs are merely wound torsion bars. They are commonly used because they are compact, easily mounted and have excellent endurance life properties. Leaf springs are long thin members that are loaded in bending.

They are used as an assembly being comprised of several layers of thin metal to obtain the correct spring rate. Leaf springs serve as both the damping member and the linkage. Torsion bars rely on the twist of a long bar to provide a spring rate to dampen car shock loading. Torsion bars mount across the bottom portion of a vehicle and are more difficult to package than others.  

3. Shock Absorbers

The Shock absorbers use a piston and cylinder along with adjustable valves to control the flow of hydraulic fluid to set the damping force in both the retract (jounce) and extend (rebound) positions. Shock absorbers are set to retract under a lower force than to extend. This action absorbs road bump forces and dampens spring oscillations resulting in better vehicle ride and control.

Signs Your Car Needs Suspension Repair

Our vehicle’s suspension system (i.e., shocks or struts) is something we often take for granted. However, after supporting several tons of metal year after year, eventually, the shocks will wear out and suspension repair will be necessary.

Some people mistakenly believe the suspension is mainly about having a smooth ride, and therefore these repairs aren’t as important as other maintenance issues like oil changes or brakes. However, having a bad suspension can greatly affect your ability to control the vehicle, especially when stopping or turning, so it’s in your best interest not to ignore this part of auto maintenance.

How do you know when it’s time for suspension repair? Your vehicle will usually tell you. Here are six things to watch for.

1. Car rides roughly

Most people can tell their shocks or struts are wearing out when they begin to feel every bump in the road, or when every bump causes the vehicle body to “bounce.” A rough ride is an obvious sign that your vehicle’s suspension needs work.

2. Drifting or pulling during turns

With a failing suspension system, you’ll often feel the vehicle “drift” or “pull” when you’re turning. This basically means the shocks are no longer keeping the vehicle body stable against the centrifugal force of a turn, increasing your risk of a rollover. If you feel this sensation while turning, it’s time to take the car to a trusted auto repair shop for servicing.

3. Dips or “nose dives” when stopping

When the shocks are worn out, you’re likely to feel the vehicle body lurching forward and downward nose-first when you apply the brakes firmly. This can actually affect your ability to stop the car quickly (a bad suspension can increase stop time by up to 20 percent).

4. Uneven tire treads

Take a look at your tires. If you notice the tread is wearing down unevenly on your tires, or if you notice balding spots, this is often a symptom that the suspension isn’t holding the car evenly, and therefore putting uneven amounts of pressure on the tires.

5. Damaged, “oily” shocks

If you can look under the vehicle, take a look directly at the shocks or struts. If they look greasy or oily, there’s a good chance that they are leaking fluid and therefore aren’t working properly. It’s probably time to get those shocks replaced.

6. Try the “bounce test”

If you suspect your suspension is going bad (perhaps due to one or more of the symptoms we mentioned above), try this simple test. With the car in “park,” press down on the front of the vehicle with all your weight, “bounce” it a few times, then release. Do it again on the rear of the vehicle. If the car continues to rock or bounce more than 2-3 times after you release it, the suspension is wearing out.

FAQ

What is car suspension?

The suspension is the system of tires, tire air, springs, shock absorbers, and linkages that connects a vehicle to its wheels and allows relative motion between the two. Suspension systems must support both road holding/handling and ride quality, which is at odds with each other.

How does a car suspension work?

A suspension works on the principle of force dissipation which involves converting force into heat thus removing the impact that force would have made. It uses springs, dampers, and struts to achieve this. A spring will hold the energy while a damper will convert it into heat.

What are the parts of Suspension System?

Following are the Parts of Suspension:
1. Wheels and tires
2. Springs
3. Shock absorbers and struts
4. Linkages
5. Bushings, bearings, and joints
6. Steering system all types
7. Hydraulic power steering
8. Electric power steering

Scroll to Top