yangzhou LM series ordinary top-top spring
there are no supporting rings at both ends, and there are multiple layers of wave springs on peak to valley. the total number of layers is greater than one layer, and the wave count of each layer is 2.5, 3.5, 4.5..., etc.; the upper and lower layers come into contact with the peak and valley, and the effective number of turns is equal to the total number of turns.