Made to drawing or sample
Tension / extension springs
Close-wound springs that resist a pull. Usually made with initial tension, so the coils stay shut until a minimum load is applied.
01 · Specification
Quick spec
| Wire diameter | Ø 0.40–2.50 mm |
|---|---|
| Outer diameter and length | Outer diameter and length as per your drawing |
| Materials |
|
| Ends | Hooks or loops to your drawing |
| Finishes | Plating and other finishing through partnersTell us the finish on the drawing. We do not plate in-house. |
| Minimum order | 5,000–10,000 pcsSmaller runs are possible with development or setup charges. |
| Quotation | Within 24 hours |
| Delivery | Ex-works Talawade (transport not included) |
02 · Engineering
What it is and how it works
An extension spring — also called a tension spring — is a close-wound helix with a hook or loop at each end. It resists a pull. Most are made withinitial tension: a preload that keeps the coils shut until the load exceeds that threshold.
Specify length inside hooks, not only overall length. Two springs with the same body can fit very differently once the hooks are bent. Also specify the angle between the hooks (in line, or at 90 degrees).
The hook is the weak point. Failures start at the inner radius of the bend, not in the body. A machine loop with a generous radius lasts longer than a sharp crossover. If the spring has been breaking in service, send the failed part — the fracture face usually tells us it was the hook.
Wire Ø 0.40–2.50 mm, same material list as our other springs. We do not grind extension springs; there is nothing to stand flat.
03 · Variants
Types and ends
Machine loop. A full loop bent back onto the body. The usual strong end.
Extended hook. The hook stands off the body so you can reach a distant pin.
Side loops, reduced eyes and 0°/90° combinations we will read off the drawing.
04 · Materials
What we coil it from
Only the grades we actually buy. Tell us the environment and we will pick from this list.
| Material | Typical standard | When to choose it |
|---|---|---|
| Spring steel (hard-drawn grades) | Typical of IS 4454-1 / EN 10270-1 cold-drawn carbon wire | Everyday torsion, extension, compression and wire forms where the part stays dry and the load is not highly cyclic. |
| Music wire | Typical of ASTM A228 / IS 4454-1 grade DH | On request, for small precision springs that need a higher tensile strength than hard-drawn wire. |
| Stainless steel 302 / 304 | Typical of ASTM A313 / IS 4454-4 | Damp, outdoor or electrical work where rust on carbon steel would be a problem. |
| Stainless steel 316 | Typical of ASTM A313 Type 316 | Chlorides or chemical splash. Tell us if the spring will see salt or cleaning chemicals. |
| Oil-tempered wire | Typical of IS 4454-2 / EN 10270-2 | On request, toward the upper end of our 0.40–2.50 mm range, for general industrial use. |
05 · Design
What to put on your drawing
- 01Wire diameter
- 02Outer diameter
- 03Length inside hooks (or overall length and hook style)
- 04Hook or loop type and the angle between the two ends (0° or 90°)
- 05Initial tension, if you know it
- 06Load at one or two extended lengths
- 07Maximum extension
- 08Material and any finish
- 09Quantity
Write length inside hooks and the hook style on the drawing. If you only have a sample, measure the body length and say “machine loop each end, in line” or attach a photo with a ruler.
Initial tension matters when the hook must not rattle at rest. If you do not know the number, describe the job: “must stay shut until the lever moves” is enough for a first pass.
06 · Use
Where this spring is used
Return springs on levers, latches and small linkages; furniture recliners; switch mechanisms; instrumentation. Automotive assemblies in our wire range — throttle, clutch and stand-return layouts — use this spring constantly.
We do not make trampoline, garage-door or rolling-shutter extension springs. Those are a different factory and a different wire.
07 · Process
How we make it
The body is close-wound and the hooks are formed to the drawing. The batch is stress-relieved. We do not grind extension springs. Finishing goes through partners. Dispatch is ex-works Talawade.
08 · Quote
Send this and we will quote in 24 hours
- Spring type and quantity
- Drawing, dimensioned photo, or the old spring
- Material, or where the part lives (dry, damp, outdoors)
- Any finish (plating is through partners)
09 · Questions
FAQ
What is the minimum order quantity?
How fast do you quote?
Can you copy a spring from a sample?
Why do extension springs break at the hook?
What hook types can you form?
What is initial tension?
What wire sizes do you work with?
Request for quotation
Send your drawing or sample. Get a quote within 24 hours.
Tell us the spring type, quantity and what it has to do. Our usual minimum order is 5,000–10,000 pcs; smaller development runs are charged.