Tension springs are the direct opposite of compression springs, in that they are closed-coiled helical springs that extend under a pulling force.
Tension springs are often referred to as extension springs and represent about 10 percent of all springs manufactured.
These springs have ends with the following loops and hooks: machine loops, small eye loops, extended eye loops, full loops, double loops, offset hook loops, half loops, long round end hooks, long square end hooks, v-hook over center hooks.
The tension springs can even be coiled with initial tension to increase the force.
Tension spring designs require the following stated factors as mentioned in the spring drawing below.