Polyurethane spring with a hardness of 90 Shore PROPER URETHANE SPRING APPLICATION GUIDELINES: – length of urethane spring should not be bigger than 2 times its external diameter – urethane springs can be fitted parallel (it is posible to double or treble the reaction force –deflection stays the same) – urtethane springs can be fitted in series (when doubling or tripling the compression produced force remains the same) – in both types of fitting sufficient space must be left for the sideways expansion of the springs during compression (for the maximum load to calculate this space use the formula: D1=1,33 D)