Spring rate refers to the amount of pressure necessary to compress a spring one inch. Three characteristics directly affect spring rate: wire diameter, the mean of the spring's diameter and the amount of active coils in the spring. Use a hydraulic spring tester to get the most accurate spring rate measurement and determine the optimal spring characteristics for your purposes. These instruments require little operation knowledge and usually come equipped with an easy-to-read digital screen for measurement readouts.
Load the spring directly into the compression chamber. Adjust the chamber so that the top and bottom come into contact with both ends of the spring. Remove your hands from the chamber and turn on the hydraulic spring tester.
Add weight to the hydraulic compression mechanism slowly. Adding weight too quickly may cause the spring to break or cause stress damage that compromises the spring's structural integrity.
Stop adding weight when the hydraulic spring tester notifies that the compressing chamber has moved one inch. Record the findings. For example, suppose the spring compresses one inch after 400 pounds of pressure is applied. Record the spring rate as 400 pounds per one inch.
Reduce the pressure in the compression chamber to zero and turn off the power. Remove the spring from the chamber.
