Schnorr Disc Springs

Disc Spring Engineering
Maximum load - minimum space - maximum flexibility

progressive spring characteristics

In many cases it is a requirement that the spring load increases progressively as the deflection increases, i.e. the rate of the characteristic increases instead of (as it is typical for disc springs) decreasing (figure 22). Such characteristic curves can be achieved in various ways. 

Figure 22 - click to enlarge

With a spring stack as shown in figure 23 - a, the discs of the 1, 2 and 3-fold layering will be flattened in sequence when a load is applied. The characteristic of such a spring stack results in the addition of the individual characteristics, as shown schematically in figure 23. The same results can be achieved by combining springs of different thickness to form a stack (figure 23 - b). 

Figure 23 - click to enlarge 

In this case it must be considered that the spring sets stacked 1 or 2-fold or the thinner single discs are subjected to high stresses if disc springs as per DIN 2093 or the factory standard have been selected. However, this overloading can be prevented with a smaller cone height or with spacer sleeves or rings to limit the deflection.

Other ways of obtaining a progressive characteristic are shown in figures 24 to 26. By inserting intermediate rings of differing thicknesses, the deflection of a spring stack consisting of disc springs of the same thickness can be limited in steps. As a result, the spring rate increases with increasing deflection (figure 24). Care must be taken to ensure that the permissible stress is not exceeded for springs without spacer rings (section 3 of the stack).

Figure 24 - click to enlarge 

A progressive characteristic can also be obtained by combining disc springs with flat washers. With this arrangement as shown in figure 25, the discs springs of a group of 2 disc springs with a flat washer between them first deflect until all the 3 parts lie parallel. From this point on the 2 disc springs act as a parallel pair and the flat washer is unloaded again, as it moves toward its original state.

Figure 25 - click to enlarge

Washers and disc springs may also have different thicknesses or be arranged so that 3 or more layers result. 

Figure 26 shows a stack consisting of disc springs of 3 different thicknesses. Here external rings are used as spacers to limit the deflection to protect the thinner springs from overloading.

Figure 26 - click to enlarge


If you should have a requirement for similar spring arrangements, please contact us. We will be glad to make the appropriate calculations for you.