If every road were perfectly level and smooth, there would be no need for shocks and struts. But roads aren’t perfectly level and smooth – they’re filled with bumps, holes and all manner of imperfections, even though roads today are better than they were when cars were first introduced.

Manufacturers quickly realized that the only way to achieve the widespread use – and sales – of cars was to address this problem. In the early years, car manufacturers weren’t competing against other manufacturers as much as they were competing against hundreds of years of buggy technology and thousands of years of horse breeding that had developed horses with a smooth gait. If the car manufacturers were to ever really make cars the new horse, they had to find a way to create a smoother ride. As a result, they developed shocks and struts, the tools used even today to give the occupants of a car a smoother, better riding experience.

The modern experience of riding in a car owes a lot to a fellow by the name of Earle S. MacPherson. He developed a system in the early 1920s that still forms the basis for the suspension system used in most automobiles today. In automotive terminology, strut is an inexact term, but we’ll use it here to refer to the suspension system. At the heart of the suspension system is the shock absorber. Think of a football team – the shock absorber is the quarterback and the rest of the team is the suspension system. Everyone on the team is important, but it’s the quarterback who has the most visible, and some would argue, crucial role.

The shock absorber supports the weight of the carriage of the car. All vibrations, both those generated by the car and those caused by imperfections in the road, are transmitted through the shock absorber. It is the function of the shock absorber to ameliorate this vibration, which it does in one of several ways. The earliest and most durable method of absorbing shock was to use a large metallic spring that wasn’t contained in any type of housing. The diameter and tension of the spring were determined by the car manufacturer. And while this made for a durable part, it led to a stiffer and less smooth ride, and is primarily used now in industrial vehicles where a comfortable ride isn’t the primary concern.

The next form developed was shock absorbers that have a lubricated spring located inside a shock absorber housing. This makes for a smoother ride than the exposed large spring mentioned before. Next in the evolution of the shock absorber were liquid shocks that use a compressible fluid inside the shock absorber housing. This is smoother still than the internal spring shock absorbers. In addition, some shocks are also available that use gas in place of other liquids. For most daily applications, the difference in price isn’t worth the difference in the smoothness of the ride. However, for some applications or for some drivers, the difference is noticeable and worth the increased expense.