Suspension in different ways

One of the most important systems that has a direct and decisive influence on driving safety is the vehicle's suspension. Its task is to transfer the forces that arise during the movement of the car, especially when overcoming road bends, bumps and braking. The suspension also needs to limit any unwanted bumps that could compromise ride comfort.

What pendant?

In modern passenger cars, two types of suspensions are most often used. On the front axle it is independent, on the rear axle - depending on the type of car - also independent or so-called. semi-dependent, i.e. based on a torsion beam, and completely dependent is rarely used. The oldest type of front independent suspension is a system of two transverse wishbones that act as a carrier. In turn, the role of springing elements is performed by helical springs. Next to them, a shock absorber is also used in the suspension. This type of suspension is now rarely used, although, for example, Honda still uses it even in their latest designs.

McPherson rules, but...

The coil spring shock absorber, i.e. the popular McPherson strut, is currently the only front suspension solution used primarily in lower class vehicles. McPherson struts are rigidly connected to the steering knuckle, and the latter is connected to the rocker arm, the so-called ball joint. In the latter case, the type “A” pendulum is most often used, which works with a stabilizer (a single pendulum with a so-called torque rod is less common). The advantage of a McPherson strut-based system is the combination of three functions in one set: shock-absorbing, carrier and steering. In addition, this type of suspension takes up very little space, which allows you to position the engine transversely. Another advantage is the low weight and very low failure rate. However, this design also has disadvantages. Among the most important are the limited travel and the lack of perpendicularity of the wheels to the ground.

Every four is better than one

Increasingly, instead of a single rocker arm, the so-called multi-link suspension was used. They differ from the solution based on the McPherson strut by the separation of the bearing and shock-absorbing functions. The first of these is performed by a system of transverse levers (usually four on each side), and coil springs and a shock absorber are responsible for the correct suspension. Multi-link suspension is commonly used in higher end vehicles. In addition, their manufacturers are increasingly installing them on both the front and rear axles. The main advantage of this solution is a significant increase in driving comfort, even when negotiating tight curves in the road. And all this thanks to the elimination of the lack of suspension on McPherson struts mentioned in the description, i.е. lack of perpendicularity of the wheels to the ground in the entire operating range.

Or maybe additional articulation?

In some car models, you can find various modifications of the front suspension. And here, for example, in Nissan Primera or Peugeot 407 we will find additional articulation. Its task is to take over the steering functions from the upper shock absorber bearing. Alfa Romeo designers used another solution. An additional element here is the upper wishbone, which is designed to improve wheel handling and reduce the effect of lateral forces on the shock absorbers.

Beams as columns

Like the McPherson at the front, the rear suspension is dominated by a torsion beam, also known as semi-independent suspension. Its name comes from the essence of the action: it allows the rear wheels to move relative to each other, of course, only to a certain extent. The role of the shock-absorbing and damping element in this solution is played by a shock absorber with a coil spring placed on it, i.e. similar to MacPherson strut. However, unlike the latter, two other functions are not performed here, i.e. switch and carrier.

Dependent or Independent

In some types of vehicles, incl. classic SUVs, dependent rear suspension is still installed. It can be implemented as a rigid axle suspended on leaf springs or replacing them with coil springs with longitudinal bars (sometimes also with so-called transverse panhards). However, both of the aforementioned types of rear suspension are currently replacing independent systems. Depending on the manufacturer, these include, among others, a composite beam with torsion bars (mainly on French cars), as well as swingarms on some BMW and Mercedes models.