As you may know, the suspension of a car is the mechanical system that allows the car to ride smoothly over the pavement or dirt as opposed to bouncing around and killing the backs of all passengers inside. If the car that you or your parents drive isn’t a supercar, then there’s a pretty good chance that suspension is a MacPherson strut suspension up front – it’s by far the most common form of suspension on the road today. But what exactly is it?
The MacPherson strut itself is a form of independent suspension, which essentially allows each of the wheels on that axle to move independently. A dependent suspension, meanwhile, essentially uses a rigid front axle to connect the two front wheels. Although dependent systems can sometimes be found on body-on-frame trucks or SUVs(the MacPherson system requires that the car have a unibody or monocoque chassis), most cars have moved on from such a system for good.
Developed in 1947 by General Motors’ Earle Steel MacPherson, the MacPherson strut system essentially uses a triangular brace consisting of the car’s chassis itself, a control arm, and a radius rod, although nowadays, one may find the latter two integrated into one beefy control arm with a stabilizer present as well. The control arm itself controls the lateral motion of the suspension and wheel, while the radius rod prevents any unwanted motion within the wheel arch. Mounted vertically to the triangular system is the spring and damper system, which consists of the damper(which itself is within a cylinder) and the spring, which work in tandem to ensure that the car stays firmly planted to the road, giving a ride as smooth or firm as is needed. Because this design takes up less space as opposed to older systems that require the use of leaf springs and the like, this system encouraged the development and manufacturing of front-wheel-drive cars, which in fact happened in the decades since the development of the MacPherson strut suspension – companies, particularly overseas manufacturers such as Honda and Volkswagen took advantage of this design to build cheaper and more value-packed cars, a trend which can still be seen today.
MacPherson himself began his career in the then-bustling city of Detroit not long after he got a mechanical engineering degree from the University of Illinois. After serving in World War I, he worked for Liberty and Hupp, two since-dead automakers, before troubles at Hupp led him to work for General Motors. From there, he worked his way up the food chain to become Chief Engineer of Passenger Car and Truck Design. After the second World War, he began his design for the suspension for an economy car called the Cadet – Chevrolet had serious concerns about the postwar auto market, which led them to develop the Cadet. In 1947, MacPherson filed a patent for this suspension, and it has since left its mark on the automotive world. Due to its aforementioned low cost and excellent packaging, MacPherson front suspensions quickly established themselves and found a home in the model lineups of numerous automakers.