The Disk Spring or Belleville Washer

The conical disk spring, often known after the original patentee as the Belleville Washer, has considerable potentialities for cushioning purposes, but its use in this country has been restricted owing to the lack of published information regarding the load-deflexion and stress-deflexion relations obtaining.

The circular conical disk of constant thickness, with a concentric hole and under central loading, is analysed in theory and design. Part I deals with theoretical aspects of the single disk, shows that a range of load-deflexion curves can be obtained (the shape of the curve depending on the ratio of the free camber to the thickness of the disk) and develops the relation between the distribution of internal stress and the ratio of the outside diameter of the disk to the inside diameter (showing that for economic utilization of space and material this ratio should not be more than two). Part II deals with the design of nests of disk springs, with particular reference to the use of these nests for buffering duties outside those for which helical springs can be easily employed. A figure for the maximum permissible calculated stress is suggested and a set of simple formulae which facilitate rapid design is developed from a consideration of the storage of energy under deflexion.