PARABOLIC SPRINGS EXPLAINED
Parabolic springs aren ’ t new , but it ’ s only been in recent times that companies have began offering a range to suit the more popular utility models . Beforehand , you had to be prepared to compromise when fitting out an aftermarket multi-leaf spring pack . They ’ ve been widely used within the trucking transport industry for years . Big trucks and trailers are loaded to their maximum allowable capacities in order to carry as many goods and supplies as possible around the country .
A parabolic spring pack looks different to the typical multi-spring pack . Let ’ s start with the base spring at the bottom of the pack . The centre of this spring is much thicker , decreasing in thickness the further you follow it to its outer edges , resulting in a tapered profile . This single leaf alone can cope with high loads and the varying forces applied to it , in comparison to a multi-leaf spring pack which distributes the load over multiple leaves .
Corrugations like these give any suspension a workout .
Our testing of the three-leaf and four-leaf packs encompassed nearly 20,000km .
A parabolic setup , however , will have additional leaf-springs to assist when a higher constant load is required . These additional leaf-springs have what ’ s known as a ‘ military wrap ’ at the fixed end of the spring where they ’ re rolled . The idea is it provides improved safety for offroad conditions . In order to reduce the friction between the leaves for a softer ride and less noise , interleaf polyblocks and silencer pads are included .
When parabolic springs are manufactured , companies can use high chromium steel that undergoes special heat treating and stress-peening processes using a parabolic tapering machine . This results in a spring that is less prone to sagging . It also allows the spring to flex more readily and provides improved traction and a smoother ride .
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