How does independent suspension work

Double wishbone suspension is the bedrock of independent systems and comprises two pressed steel or aluminium arms per wheel, one above the other, extending from the wheel hub to the frame of the car. A damper inside a coil spring is attached to the lower wishbone and at its other end to the car body.

Named for the General Motors engineer who designed it, this independent suspension system takes the form of a damper inside a coil spring. The top of the damper is attached to a so-called suspension turret visible when you lift the bonnet. Increasingly, luxury cars and SUVs have what is called air suspension, a system that uses air springs typically air-filled containers in place of traditional steel, coil springs.

As each air spring moves up or down, the system removes or adds air to maintain comfort and reduce body lean in corners. Alternatively, the system can lower the car to improve stability and reduce fuel consumption. For example, magnetic dampers are filled with a ferrous fluid. An electric current passed through the fluid can change its viscosity, or thickness, in an instant in accordance with the force being applied to the damper. Other systems use a solenoid to control the flow of the fluid inside the damper.

Go to front page. Springs Most modern car suspension systems use steel coil springs — one per wheel. Shock absorbers A spring is good at compressing and absorbing energy but not so good at releasing it, when it tends to rebound uncontrollably. Independent suspension In a car with independent suspension, each wheel — typically the front pair — is attached separately to the car body, so allowing it to move independently of the other.

Double-wishbone suspension Double wishbone suspension is the bedrock of independent systems and comprises two pressed steel or aluminium arms per wheel, one above the other, extending from the wheel hub to the frame of the car. MacPherson strut Named for the General Motors engineer who designed it, this independent suspension system takes the form of a damper inside a coil spring.

Air suspension Increasingly, luxury cars and SUVs have what is called air suspension, a system that uses air springs typically air-filled containers in place of traditional steel, coil springs. Car maintenance.

If both the front and back suspensions are independent, then all of the wheels are mounted and sprung individually, resulting in what car advertisements tout as "four-wheel independent suspension.

Of course, in the rear of the car, the steering rack — the assembly that includes the pinion gear wheel and enables the wheels to turn from side to side — is absent. This means that rear independent suspensions can be simplified versions of front ones, although the basic principles remain the same.

Because the carriage body was suspended from the chassis, the system came to be known as a "suspension" — a term still used today to describe the entire class of solutions. The slung-body suspension was not a true springing system, but it did enable the body and the wheels of the carriage to move independently. Semi-elliptical spring designs, also known as cart springs, quickly replaced the leather-strap suspension. Popular on wagons, buggies and carriages, the semi-elliptical springs were often used on both the front and rear axles.

They did, however, tend to allow forward and backward sway and had a high center of gravity. By the time powered vehicles hit the road, other, more efficient springing systems were being developed to smooth out the ride for passengers. But what about the suspensions of specialty cars, such as hot rods, racers or extreme off-road vehicles?

Although the suspensions of specialty autos obey the same basic principles, they do provide additional benefits unique to the driving conditions they must navigate. What follows is a brief overview of how suspensions are designed for three types of specialty cars — Baja Bugs, Formula One racers and American-style hot rods.

The Volkswagen Beetle, or Bug, was destined to become a favorite among off-road enthusiasts. With a low center of gravity and engine placement over the rear axle, the two-wheel-drive Bug handles off-road conditions as well as some four-wheel-drive vehicles.

Of course, the VW Bug isn't ready for off-road conditions with its factory equipment. Most Bugs require some modifications, or conversions, to get them ready for racing in harsh conditions like the deserts of Baja California. One of the most important modifications takes place in the suspension. The torsion-bar suspension, standard equipment on the front and back of most Bugs between and , can be raised to make room for heavy-duty, off-road wheels and tires. Longer shock absorbers replace the standard shocks to lift the body higher and to provide for maximum wheel travel.

In some cases, Baja Bug converters remove the torsion bars entirely and replace them with multiple coil-over systems , an aftermarket item that combines both the spring and shock absorber in one adjustable unit. The result of these modifications is a vehicle that allows the wheels to travel vertically 20 inches 50 centimeters or more at each end. Such a car can easily navigate rough terrain and often appears to "skip" over desert washboard like a stone over water. Lightweight, composite bodies, powerful V10 engines and advanced aerodynamics have led to faster, safer and more reliable cars.

To elevate driver skill as the key differentiating factor in a race, stringent rules and requirements govern Formula One racecar design. For example, the rules regulating suspension design say that all Formula One racers must be conventionally sprung, but they don't allow computer-controlled, active suspensions.

To accommodate this, the cars feature multi-link suspensions , which use a multi-rod mechanism equivalent to a double-wishbone system. Recall that a double-wishbone design uses two wishbone-shaped control arms to guide each wheel's up-and-down motion. Each arm has three mounting positions — two at the frame and one at the wheel hub — and each joint is hinged to guide the wheel's motion. In all cars, the primary benefit of a double-wishbone suspension is control.

The geometry of the arms and the elasticity of the joints give engineers ultimate control over the angle of the wheel and other vehicle dynamics, such as lift, squat and dive.

Unlike road cars, however, the shock absorbers and coil springs of a Formula One racecar don't mount directly to the control arms. Instead, they are oriented along the length of the car and are controlled remotely through a series of push and pull rods. They translate the up-and-down motions of the wheel to the back-and-forth movement of the spring-and-damper apparatus.

Like Baja Bugs, classic hot rods required significant modification by their owners. For hot rod enthusiasts, this was exactly what they wanted, for it allowed them to install more reliable and powerful engines, such as the flathead Ford V8 or the Chevrolet V8. One popular hot rod was known as the T-bucket because it was based on the Ford Model T.

The stock Ford suspension on the front of the Model T consisted of a solid I-beam front axle a dependent suspension , a U-shaped buggy spring leaf spring and a wishbone-shaped radius rod with a ball at the rear end that pivoted in a cup attached to the transmission. Ford's engineers built the Model T to ride high with a large amount of suspension movement, an ideal design for the rough, primitive roads of the s.

But after World War II, hot rodders began experimenting with larger Cadillac or Lincoln engines, which meant that the wishbone-shaped radius rod was no longer applicable. Instead, they removed the center ball and bolted the ends of the wishbone to the framerails. This " split wishbone " design lowered the front axle about 1 inch 2.

Lowering the axle more than an inch required a brand-new design, which was supplied by a company known as Bell Auto. Throughout the s and s, Bell Auto offered dropped tube axles that lowered the car a full 5 inches 13 centimeters. Tube axles were built from smooth steel tubing and balanced strength with superb aerodynamics.

The steel surface also accepted chrome plating better than the forged I-beam axles, so hot rodders often preferred them for their aesthetic qualities, as well. Some hot rod enthusiasts, however, argued that the tube axle's rigidity and inability to flex compromised how it handled the stresses of driving. To accommodate this, hot rodders introduced the four-bar suspension , using two mounting points on the axle and two on the frame.

At each mounting point, aircraft-style rod ends provided plenty of movement at all angles. The result? The four-bar system improved how the suspension worked in all sorts of driving conditions. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Under the Hood. How Car Suspensions Work.

All the power generated by the engine in a car is useless if the car can't be controlled by the driver. That's where a car's suspension system comes in. Bicanski on Pixnio. The suspension on your car maximizes friction between the tires and road and provides steering stability.

Ride : a car's ability to smooth out a bumpy road Handling : a car's ability to safely accelerate, brake and corner. Car Suspension Parts " ". Coil springs are the most common type of spring and is, in essence, a heavy-duty torsion bar coiled around an axis. Coil springs compress and expand to absorb the motion of the wheels. Leaf springs consist of several layers of metal called "leaves" bound together to act as a single unit.

This is because the upper arm, lower arm, and stub axle form a shape of a parallelogram when connected. It consists of an upper arm and lower arm which attaches to the stub axle carrier or steering knuckle. Generally, the lower arm is larger than the upper arm and they may not be parallel.

Coil Springs type I: This design uses coil springs which provides springing action to the suspension. The spring sits between the upper and lower arms. The lower arm attaches to the frame at a single point. Coil spring type II: This is the most common design which also uses coil springs. However, the lower arm attaches to the frame at two points. Coil Spring type III: In the third type, the coil spring sits between the upper arm and spring tower or housing which is a part of the vehicle body.

This design uses a steel rod known as the torsion bar. It acts as a spring to hold the upper and lower arms parallel under load. One of its ends fits into the lower arm while the other end fits into an anchor; fixed to the frame cross-member. Leaf spring: This design uses leaf spring in place of coil spring for springing action of the suspension.

One end of the leaf spring attaches to the chassis frame while the other end attaches to the lower arm.

McPherson Strut: This design uses a special unit consisting of a spring and shock-absorber. It was named after McPherson who invented it and hence, the name. Manufacturers use this design, particularly in mono-cock body construction.