Without automotive suspension systems, even a simple drive down the street would be a rough ride for cars and passengers alike.
They usually hide out of sight behind the wheels on most cars. However, it is one of the most important parts of any motor vehicle.
Here’s a look at the science behind suspension systems, from springs to sway bars.
Every car has some kind of automotive suspension system. This complex system of parts is crucial for vehicle performance and safety. It uses a series of springs, shock absorbers and components connecting the wheels to the rest of the car, allowing the driver to control the vehicle and drive smoothly even on rough terrain.
The math and physics behind suspension systems can get complicated depending on the spring used, but here’s a general overview of how it works. When a car goes over a bump in the road, no matter how small, it changes the way the vehicle moves. It already has forward acceleration parallel to the road. The bump applies an upward force on the car perpendicular to its direction of motion. This creates upward acceleration.
When the car’s wheels eventually land back on the ground, there is a lot of force that could potentially be transferred directly to the frame. The suspension system essentially cancels out the excess vertical energy created by the vehicle landing after bouncing off the ground from the bump in the road. The suspension system absorbs and dissipates the force to keep it from being transferred to the frame and passengers inside.
Different types of cars use various suspension system configurations. For example, race car systems are tuned up drastically differently from the ones on consumer street cars. It can significantly impact how a car handles and grips the road. Despite setup differences, every suspension system includes a few common components.
The springs are the heart of any automotive suspension system. There are several different types, including metal coil-style springs, as well as hydraulic systems and even air springs.
The coil is the most common type of spring used in automotive suspension systems. This is what most likely comes to mind when people imagine a spring. It is a metal coil designed to oscillate so it can absorb the shock of a car’s tyres going over bumps. Different vehicle models use various coil springs depending on mass, desired ride softness and handling.
Hydraulic and air springs are also used in many cars. These two types of springs simulate the action of a physical metal spring using hydraulic fluid or compressed air. Air springs tend to offer better durability and customisation in addition to easier maintenance. Many luxury vehicles are sold with air springs due to their superior smooth driving experience.
Springs are the core of the suspension system, but they can’t do everything. They are good at absorbing energy caused by going over bumps, but they aren’t very good at dissipating it. That’s what dampers are for. Without them, the springs would simply oscillate until they eventually ran out of energy, making for a very bouncy ride.
There are two main damper components: shock absorbers and struts. These two parts are similar, but each serves a distinct purpose. Shock absorbers are tubes of hydraulic fluid. When the springs fill up with kinetic energy going over a bump in the road, the shock absorbers dissipate it by turning it into thermal energy that warms up the hydraulic fluid.
Struts offer similar hydraulic shock absorption, but they also provide structural support for automotive suspension systems as a whole. They help keep the wheel aligned and provide steering and handling support for the car. Some vehicles only have struts or shock absorbers, while others use a combination of both. Front-wheel drive models often opt for struts.
While not directly part of the suspension system itself, the steering linkage or link is an important component connecting to the wheels of a car. It’s a series of connected parts that tie the steering wheel to the car’s wheels. Suspension systems and steering links must work together to make cars turn and handle safely without rolling or losing traction. In fact, the relationship between steering, handling and suspension systems is critical to race car performance. The tie rods on race cars’ steering links are adjusted to go “toe-out,” which turns the wheel slightly outward. This helps race cars zip back and forth across the track faster but reduces the handling stability of the suspension system.
In consumer street cars, the steering tie rods are tuned so the wheels are “toe-in,” meaning they are pointed slightly inward. This keeps the vehicle moving in a straight line and even helps the suspension system handle bumps and rough roads more smoothly. The toe-in configuration also makes cars easier to drive at higher speeds, such as on motorways.
Passengers can often feel the sideways force on the car when driving around a turn on the motorway, yet the outer wheels don’t leave the ground. This is possible thanks to the sway bar, also called the anti-roll bar or stabiliser bar. This piece of automotive suspension system links the left and right parts together like a bridge.
When the car takes a turn where there is more weight on one side than the other, the sway bar twists to redistribute weight. This prevents the vehicle from rolling or flipping over and maintains all four tyres’ grip on the road. As a result, the car is safer going around turns. The uneven force cars experience while turning is also why roads are sometimes sloped or banked. This accounts for centrifugal force and helps maintain the vehicle’s grip on the road.
Automotive suspension systems are a crucial part of every vehicle. They keep cars from breaking every time they go over a bump and make the driving experience much more enjoyable. Most people may not think too much about the springs keeping their vehicle steady on the road, but suspension systems are marvels of physics and engineering.