ABOUT LEAF SPRINGS
Leaf springs are the most cost efficient suspension solutions for commercial vehicles. Despite of the fact that the history of leaf springs started more than 100 years ago, we can find leaf springs in the latest modern commercial vehicles. Leaf springs on commercial vehicles are not standardised parts therefore each vehicle manufacturer develops own solutions and on one vehicle platform several different variants are used. The results of this is a huge number of article numbers on the market. From technical point of view, leaf springs have three main types.
MULTI LEAF SPRINGS
Multi leaf springs (often said: conventional leaf springs) are the oldest type of leaf spring. They are made from spring leaves with constant cross sections. They are used mainly in construction vehicles, agricultural vehicles and even on rear axles of modern pick ups. Advantages of multi leaf spring are the robustness and cheap repair possibility. In most of the cases no additional stabiliser is needed.
Parabolic springs are more modern leaf springs. Spring leaves are tapered to parabolic form; the spring thickness decreases from the center of the spring till the spring leaf ends. You can recognise parabolic leaf springs from the gaps between the spring leaves. Parabolic springs can provide the same spring rate like multi leaf springs with 30% – 40% less weight.
Air links (often said trailing arms, linker springs or beam springs) are used together with air suspension. They are also a special type of parabolic springs.
POSSIBLE PROBLEMS WITH LEAF SPRING
Why leaf springs might break sometimes? There can be several reasons: material problems (inclusions in spring steel, surface problem), leaf spring production mistakes (wrong heat treatment, microcracks or grooves on surface), service installation problems (U-bolt nuts are not tightened), usage (spring surface damaged during usage, bad road conditions, overload of vehicle) and many more. The topic of "spring breakage root causes" will be discussed in the knowledgebase later as a separate topic.