4X4 PROFESSOR

Why does your vehicle need shock absorbers, how do they work, and when do they need to be replaced? We went in search of answers.

Long ago, when people still drove around in ox wagons, suspension was not that important. But when the internal combustion engine enabled our ancestors to whizz around at 60 km/h, even decent dirt roads became a bumpy, disagreeable ordeal. Out of sympathy for teeth and spines, the lab coats designed suspension. But suspension on its own isn’t enough to absorb jolts; it can only store the energy of a jolt by bouncing up and down. The clever guys had to come up with a plan to keep the bucking of an agitated suspension system under control. C.L. Horock designed the first hydraulic shock absorber in 1901, but it only dampened in one direction. Mechanical shock absorbers like Gabriel Snubber’s device that contained some type of belt coiled up inside it was also popular, but it was Maurice Houdaille’s 1908 patent on which the majority of modern shock absorbers are based. Houdaille’s concept really took off when Henry Ford used a version of it in his 1927 Ford Model A. How do shocks work? As the name implies, a shock absorber absorbs shock. But to put it more precisely, a shock absorber absorbs the kinetic energy stored in the springs of your vehicle’s suspension after its wheels hit unevenness in the road. Your car’s suspension stores kinetic energy by means of movement. When a wheel bounces, the springs of the suspension are compressed, but all of that energy needs to be released somehow. The suspension oscillates until all of the energy is spent – this may take a while. This is all well and good, but if the wheel repeatedly bounces, like on a dirt road, while the spring is still busy oscillating, the vehicle will eventually rebound so erratically that your teeth will chatter and you’ll lose control over your vehicle. This is where the shock absorber comes into play. A shock absorber dampens the movement of the suspension. This dampens the rebound and shortens the oscillating period by converting a large portion of the kinetic energy into heat. This heat is absorbed through oil inside the shock absorber. When hot and compressed oil comes in contact with air, it starts to froth and bubble, reducing the shock absorber’s effectiveness. Modern shock absorbers therefore contain nitrogen that separates regular air from the oil and also helps to cool down the shock absorber a lot faster. >