Schnorr Disc Springs

Disc Spring Engineering
Maximum load - minimum space - maximum flexibility

the disc spring story

A disc spring is a conical disc which can be loaded along its axis either statically or dynamically. The loads are normally applied to the upper inner edge and the lower outer edge. Either a single spring or a stack or springs can be used.

Although the disc spring has found a wider application during the last few decades, it is still an old established machine component. The original inventor is not known, but more than 130 years ago (on 26.12.1861 to be precise) Julien Francois Belleville of Dunkirk was granted French Patent Number 52399 for a spring design which already contained the principle of the disc spring. The importance this invention achieved is unknown, but the fact that even today France and the Anglo Saxon countries still speak of “Belleville Springs” infers a broad dissemination of this or similar springs. Today this tends to denote a disc spring of inferior quality, which still reflects that not always satisfactory design and function of springs at that time. This is no wonder considering that in the last century neither the theoretical conditions for calculations nor the necessary materials for manufacture were available.

Not until 1917 did Fr. Dubois develop the theory on which the calculation of the disc spring is based in his dissertation “The Strength of the Conical Shell” at the ETH in Zurich. However, it still took several decades until this was adopted in practice. For a long time disc springs continued to be calculated – if at all – in accordance with the theory of the flat perforated plate. Then in 1936 two Americans, Almen and Laszlo, published a simplified method for calculating disc springs.

In the meantime, the disc spring had been introduced into numerous areas of technology. Starting with applications in the construction of cutting and presswork tools, where the disc spring is especially advantageous because of the large number of variations possible with the same spring size, new applications were quickly found in machine, engine and motor vehicle manufacture.

Technological development is often advanced rapidly in time of war. The disc spring was no exception and its spreading was strongly promoted by the Second World War. For example, its excellent damping characteristics with multiple layers were utilised for the suspension of artillery breeches. Calculation methods and material technology were further developed. After the war the conditions were created for the introduction of the disc spring into all areas of technology.

Adolf Schnorr, who had founded a mechanical workshop in 1908, already began to experiment with the disc spring in the 1920s. He needed high-quality springs for precision tools, with which he had made himself a name and had come across the disc spring after a long search. As he was unable to procure them anywhere, he went about producing these springs himself. Initially he produced only for his own needs, but the demand had already increases so greatly by the early 1930s that he decided to give up tool-making for customers and devote himself entirely to the manufacture of the “SCHNORR Spring”. From that time on SCHNORR has manufactured disc springs and continually opened up new applications with its many domestic and foreign customers.