mechanical springs

An extension spring is a coil that is wound into a spiral and tightly wrapped to meet various tension needs. The type of extension spring end type that you need depends on the application you are using them in. By learning more about the applications for springs and the different end types, you can choose the best solution for your needs. 
Purpose and Uses for an Extension Spring 
The purpose of an extension spring design is to provide extended force when someone or something pulls the spring separate from its primary length. It often has a hook or loop on the end to connect to components that pull on the spring tension. During periods of no tension, the spring returns to its unloaded or preloaded state. 

Some of the most common uses for an extension spring are push-pull levers, rocking horses, screen doors and trampolines. However, they can be used anywhere that you need extended force. 

These are your options when it comes to extension spring end types:

Machine and Crossover Center Hooks

The two most common types of extension spring ends are machine and crossover center hooks. Machine hooks form directly off the extension spring. Then, they circle over and across the center of the spring end. The bend begins at three-fourths of a coil out. They’re stronger than crossover center hooks because the bend radius is less pronounced.
Crossover center hooks bend across the center and form a circle at the end. With a more pronounced bend radius, the hook is made by lifting the last coil and twisting it toward the middle of the extension spring end. As a result, they cross the center.

Side and Extended Hooks

Although less popular, side and extended hook ends are useful for extension springs in certain situations. More economical than crossover center hooks, the side hook forms a circle on the same plane as the outside diameter of the extension spring. It’s made by bending the last coil out. As a result, the spring is offset, which is the perfect solution for providing tension that can’t interfere with your connecting component.
An extended hook is similar to a side hook in its use and function. The difference is that the final coil bends with a gap between the end of the wire and the other coils. Because of that, the spring has a shorter body but longer end hook to deliver more force.

Double Loop and No Hooks

As the name sounds, a double loop end has two coils, and there’s no gap between the end of the wire and other coils. This extra loop provides more strength on the extension spring ends to prevent breakage.
On the other hand, an extension spring with no hooks has an advantage over those with hooks because there’s no fatigue or stress. You use it to thread a bolt into the inner diameter to secure the ends. It’s the most economical of the ends because it has a better life cycle, distance and pulling force.

Customized Ends for Extension Springs

If one of these extension spring ends doesn’t work for you, you can always customize the ends according to your needs. An expert can help you create the right spring design and end.

Need help choosing an end type for your extension springs. Contact The Yost Superior Co. Today.