Also searched as: Double Looped Extension Spring
Extension springs stretch along the horizontal track to counterbalance the door, with double-looped ends as the standard termination [ESTIMATE]. They are specified by simple, hard numbers — a real retail replacement spring is rated 140 lb door weight, 7 ft door height, ASTM 229 oil-tempered steel, double-looped, dark-blue finish [SOURCED https://www.amazon.com/dp/B0BRNVTKKQ] — which is exactly how repair buyers search and order. One non-negotiable: every extension spring must run on a containment/safety cable so a broken spring cannot whip [ESTIMATE].
RAX produces extension springs in-house with the rest of the door hardware — wire gauge, length and end loops matched to door weight and track geometry, validated in the 100,000-cycle fatigue lab. Extension springs sit in a growing but smaller market segment (industry research forecasts 1.5–2.5% annual growth vs 2.5–4.0% for torsion [SOURCED https://www.researchandmarkets.com/reports/6157631/overhead-door-spring-global-market-insights]), and RAX supplies both types plus safety cables from one factory.
Double-loop ends and safety-cable requirement are industry conventions [ESTIMATE]. Retail spec example (140 lb / 7 ft / ASTM 229 / double-looped) verified from a live product listing [SOURCED https://www.amazon.com/dp/B0BRNVTKKQ]; market growth data verified [SOURCED https://www.researchandmarkets.com/reports/6157631/overhead-door-spring-global-market-insights]. RAX-specific claims are from the approved brand brief.
Custom width × height, RAL color and configuration. Large industrial doors from prototype to container-load, full flexibility on order quantity.
Validated against a 100,000-cycle fatigue testing protocol in our in-house lab.
ISO 9001:2015 and CE to EN 13241 / EN 12453, with SGS material reports.
English manual + wiring diagrams; operators pre-set before dispatch.
| Product | Extension Spring (also: Double Looped Extension Spring) |
| Category | OEM Door Components |
| Size range | Wire diameter and stretched/free length made to door weight and height; double-looped ends standard [ESTIMATE]. From single pairs for repair services to container loads for OEM lines. |
| Materials | Oil-tempered spring steel (ASTM A229 is a common spec — a benchmark retail spring is rated 140 lb / 7 ft in ASTM 229 steel [SOURCED https://www.amazon.com/dp/B0BRNVTKKQ]); galvanized or painted finish; use with containment cable [ESTIMATE]. |
| Color / finish | Full RAL custom (common RAL9006 / 9010 / 7016 / 5010), wood-grain, PVDF, anodizing |
| Power | Not applicable — passive, unpowered component. RAX can supply matched operators, servo drives and smart controls from its full-category one-factory range. |
| Certification | CE EN 13241 / EN 12453; product-specific test data confirmed per project |
| Order | Custom engineered to your exact opening, specification and RAL color |
Springs are rated by load and door height — e.g. a benchmark retail unit is 140 lb / 7 ft [SOURCED https://www.amazon.com/dp/B0BRNVTKKQ].
Match wire diameter and free/stretched length to track geometry; send a sample for reverse measurement.
Always specify the containment cable — a broken extension spring without one is a whip hazard [ESTIMATE].
Springs work in pairs; confirm finish (galvanized/painted) and end-loop type [ESTIMATE].
RAX supports full private-label production of the Extension Spring: custom RAL panel colors, operator matching, packaging printing and installation-manual translation (EN/ES/FR/AR/RU). Start with an OEM sample and scale to container-load branded production. Custom molds, Tooling records are archived for up to 5 years — no extra tooling fee on repeat orders, all under strict NDA.
Industrial, commercial and garage doors and gates — the harmonized basis for CE marking.
Safety in use of power-operated doors — force limits and test methods for operators.
Wind (EN 12424), thermal (EN 12428), fire (EN 1634-1) etc. confirmed per product during enrichment.
Extension springs are made to door weight and height with double-looped ends [ESTIMATE] — a benchmark retail unit is rated 140 lb for a 7 ft door in ASTM 229 oil-tempered steel [SOURCED https://www.amazon.com/dp/B0BRNVTKKQ]. Send door weight, height and a sample or drawing; RAX quotes pairs with matched safety cables from prototype to container-load, and small repair batches ship fast.
We are a pure manufacturer and do not provide on-site installation. Every order ships with an English installation manual, wiring diagrams for your local installation team; operators are pre-set and tested before dispatch.
RAX holds ISO 9001:2015 and CE to EN 13241 (industrial door product standard) and EN 12453 (operator safety), with SGS material reports and product liability insurance. Components are engineered to help the finished door satisfy EN 12604 (mechanical aspects: strength, cycle durability, finger-pinch and spring/cable safety), and product-specific test data (fire, wind, thermal) is confirmed per project against the matching standard.
Yes. RAL panel colors, operator matching, packaging printing and manual translation (EN/ES/FR/AR/RU) are all supported, from an OEM sample to container-load branded production.
Sample 7–15 days; standard container 12–20 days; custom first order 20–35 days. Door body 2-year warranty, operator/motor 3 years (servo 5 years), with spare parts dispatched by DHL/FedEx within warranty.
Factory inspection report, 100,000-cycle fatigue test record, FAI / pre-assembly photos, English installation Manual + Wiring diagrams, CE Declaration of Conformity, and export packing (steel frame + pearl cotton + stretch film).
Or email info@raxdoor.com
Send your opening size and duty requirements — we reply with a proposal and lead time.
