The suspension is a key element for the good behavior of our car. There are many types with their advantages and disadvantages, but among all of them, the most used and known today is the McPherson strut. A system devised by Earle S. McPherson in the 40s and patented by Ford in 1953, which today is used for front axle of most cars.
Being the brand that patented this ingenuity, the first models that mounted this type of suspension were the Ford Consul and Ford zephyr. The first produced from 1951 to 1962 and the second from 1950 to 1972, but both belonging to the same range of cars made in the UK.
Advantages of the McPherson strut
The McPherson strut has many advantages. The most important is your simplicity and low manufacturing cost. But it is that in addition the appearance of him supposed the reduction of the suspended mass of the car, an improvement in terms of the support of the wheel on the ground and the volume and weight reduction of the System.
The McPherson suspension has another peculiarity compared to other suspensions of the time. Also acts as the axis of rotation of the wheel when we move the direction of the car. That is, the wheel pivots around the vertical axis of the suspension. At least according to the design that it had in its initial forms.
As you can see in the pictures of your patent, shock absorber and spring assembly it was completely vertical with respect to the ground. Later this suspension has had different inclinations depending on the model, but it can still be said that the wheels turn using the lower suspension anchor as an axis. Although that strictly he does it with the shield and CV joint.
Disadvantages of the McPherson suspension
However, this type of suspension also has some disadvantages, for example, due to its design, the wheel cannot move completely vertically. Being attached by means of a lower arm and this to the car by means of an axis, the suspension modifies its vertical angle during movement. To understand it, it is enough to know that since said arm is connected by a fixed point, it can only move in an arc. Since the suspension is anchored to the other end of the arm, it changes its tilt depending on where it is on the arch.
Another drawback of this type of suspension is that transmits vibrations directly to the car chassis. Which translates into greater noise in the passenger compartment if the necessary insulators such as silentblocks are not added. The reason for this is that the shock absorbers are directly attached to the chassis, something that can usually be seen when the hood of the car is opened.
How it works
Of course, in the McPherson suspension it is the shock absorber and the spring that absorb the potholes. It keeps the wheel in the right place thanks to the stub axle and this in turn is kept in position thanks to the shock absorber itself and the lower arm. The interesting thing is that thanks to this operation it also allows the wheel to pivot to let the steering of the car do its job.
Thanks to the functional separation of longitudinal forces on the front support and lateral forces on the rear support, a great walking agility, as well as great safety and very high interior comfort without these two forces influencing each other.
basic parts
- Coil spring and damper assembly: it is in charge of absorbing the imperfections of the road and potholes. Specifically, it is the spring that is responsible for doing this, while the shock absorber eliminates the rebound effect that the spring would have on its own. It is anchored to the chassis by its upper part, so as in most suspensions you have to use a coil spring compressor to place it.
- spindle: this is where the coil spring/shock absorber assembly is attached at its lower part. Through the spindle passes the wheel axle. Along with the shock absorber, it would be the vertical side of the triangle that forms this suspension.
- lower arm: It is attached to the frame on one side and to the lower part of the spindle on the other. In the triangle formed by the elements it would be the lower side.
More McPherson strut parts
These are the elementary parts of the McPherson strut, but there are actually many others in between. For example, in the upper part where it is screwed to the chassis it also has a fixing plate and a needle bearing to fit properly.
The spring and damper assembly has the top and bottom cup to fix one to another. And on the bottom bar you have a ball joint and bushing to anchor it to the stub axle and frame respectively. Besides, the stabilizer bar it helped keep the assembly in place longitudinally, so it was an important element for this type of suspension.
Over the years, the McPherson strut has been perfected to the suspension we see today in most middle-class vehicles on the market. In premium range cars you can find others such as the deformable Parallelogram with pneumatic springs.
Picture 4 – Nick Ares