Variation of the Rigidity of Laminated Springs

Abstract

As the result of long use, the load-deflection characteristics of existing laminated springs for passenger and freight cars are varied, that is, with the increase of load, spring rigidity increases over the initial value, whereas it decreases under light load. The authors have investigated causes of the rigidity change and have found that the main causes lie in the opening of leafends and the binding of leaves at spring center. To maintain the initial rigidity, 1) leaf strength should be so decided that the shorter-leaf-yielding may be prevented or the nip should be reduced, 2) rust-proofing proccsses such as oil-coating should be applied to the leaf-surfaces. The pressure distribution between adjacent leaves was measured and pressure concentration on both ends of leaf was made clear, which, it is considered, will serve as data for calculation of spring stress.