Extension springs
Tension springs, or extension springs, are designed to absorb and store energy by resisting stretching forces, returning to their original form when the load is released. Their strength and durability make them essential in applications ranging from everyday mechanisms to heavy industrial machinery.
At Lesjöfors, we supply a comprehensive range of standard tension springs directly from stock, along with custom solutions tailored to exact specifications. Whether you need a one-off prototype or large-scale production, our technical expertise, flexibility, and global reach ensure the right solution at every stage.
Technical specifications
- Wire diameter:
0.1 mm to 65 mm
- Features:
Hooks, loops, screw plugs, shackles, and custom ends
- Materials:
Carbon steel, stainless steel, alloys
- Surface treatments:
Available on request for added protection
- Certifications:
ISO 9001, ISO 14001, ISO 45001, ISO 13485:2016, IATF 16949 certified
- Stock & custom options available
Extension spring
What are tension (extension) springs?
Tension springs (also called extension springs) are coil springs that work by stretching. Unlike compression springs, which resist being pushed together, tension springs are designed to resist pulling forces and return to their original shape when released.
At Lesjöfors, we design and manufacture tension springs of all sizes, from 0.1 mm to 65 mm in wire diameter for a range of industries, including automotive, construction, medical, defense, and energy.
Product range & stock availability
Stock extension springs
At Lesjöfors, you’ll find one of the widest ranges of stock tension springs in the industry. Choose from a variety of sizes, materials, and strength levels to suit your exact needs. With a worldwide network and simple online ordering, it’s easy to get the right springs – delivered quickly, wherever you are.
Custom tension springs
Every application presents its own challenges – and our tension springs are created to meet them. We work closely with you to design springs tailored to your exact performance needs, adjusting dimensions, selecting materials and operating conditions. Wherever you operate, our global network ensures reliable, fast fulfillment.
With decades of industry experience, we ensure that each spring is not only functional but optimized for its intended use.
Explore tension spring types and end fittings
Choose from a menu of ends and attachments. The shape and style of each spring end determines how and where it connects, ensuring a secure fit every time. Popular types include:
English loops for straightforward connections
German loops for strong, smooth pulling
Extended hooks for extra reach
Side hooks and side loops for compact spaces
Screw plugs and shackles for secure mechanical setups
Advanced tension spring manufacturing
We craft tension springs using advanced hot and cold coiling, with wire diameters from 0.1 mm to 65 mm. Each spring can be made with just the right pull force and initial tension. Choose from a wide range of end fittings, all built for strength and reliability. Every spring meets strict quality standards, so you can count on lasting performance.
- CNC Coiling
- Quality Assurance - ISO 14001, ISO 45001 and ISO 9001 certified, ISO 13485:2016, IATF 16949 certified
- Engineered for maximum strength and durability
How do extension springs work?
A tension spring works by resisting pulling forces. As it is extended, the spring absorbs and stores energy. Once stretched, it generates a return force that pulls the connected components back to their original position. Picture stretching a trampoline mat or a garage door rising. That’s a tension spring in action.
The coils tighten under force, hold energy, then quickly release it when needed, whereas in an unloaded state, the coils remain tightly closed against each other.
This built-in resilience powers smooth, safe movement across countless uses. If you want to explore the science behind it, check out our insights on tension spring mechanics.
Extension spring materials
Choosing the right material gives your spring lasting strength and resilience. Lesjöfors offers a comprehensive range so you get the best match, no matter the conditions.
Chrome silicon and chrome vanadium provide outstanding durability in high-stress, heavy-load environments, while stainless steel delivers corrosion resistance in damp or challenging conditions. Nickel and titanium alloys perform reliably under extreme heat and specialist requirements, and copper alloys combine strength with excellent electrical conductivity.
Our engineers offer expert advice on material selection, supported by a worldwide network of specialists. Together, we ensure every spring performs at its best, using the optimal material for each application.
Trusted in energy and sporting goods
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