An extension spring with hooks at both ends for sports and training equipment, where the load is applied by a person and the spring is often gripped or stepped on. Failure here is a safety matter rather than a maintenance one, which changes how the part is specified.
Sports springs are loaded to near their limit by users who do not read specifications, which is why the design margin is set generously.
The hook root is where a loaded spring fails. Forming it as part of the coiling cycle keeps the transition smooth.
Equipment using several springs gets them from one run so the resistance is even across the frame.
Inspect hooks for opening at every service interval and replace springs as a complete set. Never bridge a broken spring by shortening and re-hooking the remaining body.
Springs from different batches giving uneven resistance across one piece of equipment
Hooks opening under load where the end was simply bent from the last coil
Dimensional and load figures are set per order against your drawing or sample, so they are marked TBC rather than filled with catalogue numbers.
| Product Type | Tension Springs |
|---|---|
| Raw Material Options | Stainless steel, Spring steel, Carbon steel, 65Mn, Music wire |
| Wire Diameter Range | 0.1-8 mm |
| Surface Treatment Options | Zinc plating, Nickel plating, Silver plating, Gold plating, Tin plating, Galvanizing in various colours, Dacromet, Black oxide, Phosphating |
| Standard | ISO, non-standard and OEM drawings |
| Processing Route | Material sourcing → Coiling and forming → Heat treatment → Surface treatment → Quality inspection → Packing → Shipping |
| Inspection Equipment | Grinding and shot peening machinery; Precision tensile strength testers; Magnetic powder flaw detectors |
| Packing | Plastic bags, cartons or pallets, or packing to your own specification |
| Payment Terms | L/C, T/T, D/A, D/P, Western Union, 30% deposit before production, 70% balance before shipment |
| Lead Time | 7-15 days after the order is confirmed |
| Minimum Order Quantity | Quoted per part — tell us your requirement (TBC) |
| Dimensions and Load Rating | Made to your drawing or sample (TBC per part) |
Every batch follows the same seven step route, with tensile testing and magnetic powder flaw detection carried out before packing.
Available in Stainless steel, Spring steel, Carbon steel, 65Mn, Music wire, in wire from 0.1-8 mm, with any of our nine surface finishing routes. Geometry, end treatment and finish are all specified per order.
ISO 9001, SGS certificate and RoHS report (stated on the legacy site, certificates pending re-confirmation). Certificate copies are sent on request once re-confirmed.
Against an elastic band or cord, a steel extension spring gives a predictable, repeatable resistance that does not degrade with UV exposure, at the cost of more weight and a harder end stop.
More than industrial parts, because users overload them routinely. Tell us the intended load and we will design with that reality in mind.
Closed or partially closed hooks are possible and are worth considering for user-facing equipment. We confirm the form at sampling.
Yes. Springs for one machine are produced and packed as a single run.
Send your drawing, dimensions or a sample. We will confirm the specification and come back with a price and a lead time.
