It must be confessed that the inventors of the mechanical arts have been much more useful to men than the inventors of syllogisms.


Springs are among the most common machine element, and have a wide variety of forms and functions. This chapter introduces the most common types of springs and describes their design. The chapter begins by describing the materials and properties that are needed to produce an effective spring, and discusses the unique strength characteristics that arise from spring metals that have been highly cold worked. Helical compression springs are analyzed, with geometric concerns and associated forces and stresses, and the approach is then applied to extension springs. Torsion springs are then examined, and the normal stresses that result from an applied moment are derived. Torsion springs are also unique in that the number of active coils changes as the spring deflects. Leaf springs are then summarized; these are cantilevers that are commonly applied to vehicle suspensions because of their compact designs. Gas springs are commonly used as counterbalances, but also introduce favorable damping characteristics. Belleville springs, also known as Belleville lock washers, are a special conical disk spring that has a naturally small profile, and that can be stacked in series or parallel to accentuate their performance. Finally, wave springs are discussed, which use a helical pattern with a superimposed wave; the resulting springs result in very compact designs.