Definitions for "Spring Rate"
In very low pressure application the more significant force may be the spring rate which is expressed in pounds per inch of motion. Thus, as the pipe grows due to increasing temperature, the bellows will resist compression by the force noted in the spring rate.
The rate of compression of coil springs. One of many factors determining how a car will handle on a race track.
the amount of force necessary to compress the spring, usually measured in one inch increments. A straight rate spring will take the same amount of force for the entire travel of the spring. A 500 lb rated spring will take 500 lbs of force to compress it one inch, another 500 lbs (total 1000) to compress it the second inch, and so on until the end of the spring travel. Now a progressive rate spring changes the force requirement as the spring is compressed. A 500-600 lb rated spring will require 500 lbs of force to compress the spring the first inch, another 520 lbs (varies depending on spring length) to compress it the next inch all the way to the last inch where an additional 600 lbs of additional force is required to compress.