BarrelSprings

Barrel springs are a type of compression spring used to produce linear or nonlinear force where the top and bottom outer diameter are smaller than the center outer diameter. Barrel springs can be made with many different diameters which give you numerous design options.
Barrel springs are specialty springs and more difficult to design than regular compression springs because the force they produce is not always linear. As you can see from the two pictures to the right barrel springs can have very different shapes. The force of a barrel spring stops being linear when the coils begin to telescope on the spring. You can see for the blue spring this would happen much faster than the silver spring due to the extreme differences in size and shape. If you wish to test the load on your barrel spring you will need to use a load tester.