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Flat Springs

Power springs

Power springs, also known as flat spiral springs, are tightly wound strips of spring material designed to store and release rotational energy. They release steady torque for winding and return in compact mechanical assemblies. When mounted between a shaft (arbor) and a housing (case), the spring produces controlled, consistent torque as it is wound and unwound. This design enables precise, repeatable retraction and long cycle life. Power springs are ideal for retractable mechanisms, counterbalances, and constant-torque applications where smooth performance and space efficiency are critical.

At Lesjöfors, power spring manufacturing focuses on application needs. We tailor design, materials, and dimensions for durability, long life, and fast development.

Technical specifications

Types:

Available in conventional and pre-stressed configurations 

Strip thickness:

Up to 2 mm, depending on design

Features:

Delivers steady torque and smooth retraction over multiple cycles 

Materials:

Stainless steel & carbon steel with protective finishes

A metallic, spiral-shaped flat spring set against a white background, with smooth surfaces and sleek edges.
A neatly coiled power spring of flexible metal sits on a reflective surface. The spiral design creates a sense of balance and precision.

Find the right power spring solution - standard or custom

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Power springs of varying sizes are arranged on a reflective surface. The arrangement highlights their circular shapes and metallic shine.

What are power springs?

Power springs are flat, spiral-shaped springs made from coiled strip material. Designed to store and release energy and deliver controlled torque, they enable smooth winding and return in compact assemblies. The torque-deflection characteristics of a power spring are nonlinear. This is due to changing amounts of active material during operation, inter-coil friction and hysteresis effects within the assembly.

Positioned between a shaft and a housing, they generate torque as either the arbor or the case rotates, ensuring smooth, repeatable retraction across numerous cycles. Standard models typically support around 20 turns, while prestressed variants can reach up to 50 turns, depending on the strip size and available space. 

 

Product range & stock availability

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Stock power springs

Lesjöfors offers a wide selection of stock power springs and flat spiral springs through its online shop and global distribution network. Standard sizes are ideal for applications such as cable reels, hose reels, and safety belts. Each spring is engineered for consistent torque delivery and a compact footprint.

To simplify your experience, we provide local support, CAD resources, and strategically located warehouses, ensuring quick assistance, seamless ordering, and fast delivery.

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Close-up of a metallic power spring in a workshop setting, with a blurred background. The spring's shiny coils evoke precision and industrial craftsmanship.

Custom power springs

Custom power springs are built to match each project. We look at torque, turns, space, duty cycle, and target life. Engineers then adjust strip width, thickness, and length to suit, with material choice depending on performance needs and required cycles.

Prototypes are built quickly, tested against clear standards, and refined. With support from our global engineering teams at every stage, Lesjöfors delivers custom springs that ensure smooth retraction, consistent torque, and long-lasting reliability.

Types of power springs

We offer several types of power springs to suit different applications:

  • A power spring in silver, viewed from above on a white background. The concentric circles create a modern, minimalist design.

    Conventional power springs

    Flat strip wound in the flat state for stable, predictable torque. Designed for long service life where steady retraction matters.

  • A power spring in silver, viewed from above on a white background. The concentric circles create a modern, minimalist design.

    Pre‑stressed power springs

    Cross‑curved and back wound to raise torque and working turns. Ideal for tight packages that still need smooth, controlled retraction.

  • A power spring in silver, viewed from above on a white background. The concentric circles create a modern, minimalist design.

    Cross‑curved power springs

    Formed curvature that matches torque‑rotation targets with high efficiency. Available as stocked options for fast builds and reliable performance.

A person in a yellow shirt operates a blue machine, adjusting a mechanical part with precision, highlighting industrial focus and concentration.

Advanced power spring manufacturing

Our power springs are precisely engineered to deliver consistent torque, even under demanding conditions. Each design follows a rigorous manufacturing process, with defined quality checks to ensure reliability, durability, and safety. Every component and material is carefully selected to match the application’s torque requirements, rotation range, spatial constraints, and duty cycle.

Key technical features include:

  • Application‑driven coiling methods for accurate torque and turns
  • Tight dimensional control of strip width, thickness, and length
  • Certified quality systems: ISO 9001, ISO 14001, ISO 45001
A power spring in silver, viewed from above on a white background. The concentric circles create a modern, minimalist design.

How do power springs work?

Power springs store and release energy in a tightly wound strip of spring material, releasing it as controlled torque to rotate an arbor or housing. Installed between a central shaft (arbor) and an outer case, the spring winds tighter as one component rotates, building torque in the process.

When released, it unwinds smoothly to deliver consistent, repeatable retraction across multiple turns. This precise motion drives compact retraction mechanisms where steady torque and reliability are essential. These mechanisms include cable reels, hose reels, and safety belts.

A person wearing gloves holds up a power spring, reflecting their face. The background shows a blurred industrial setting with metal beams and lights.

Power spring materials

Power springs are crafted from materials and finishes specifically chosen to meet performance requirements, environmental conditions, and service life expectations. Each selection is made with care, considering factors such as corrosion resistance, load demands, and exposure to harsh elements. The result is consistent torque delivery and a reliable cycle life you can count on.

Common materials and finishes include:

  • Stainless steel for corrosion resistance in demanding environments
  • Hardened and tempered carbon steel for strength and long cycle life
  • High‑performance texture‑rolled carbon steel for efficient torque density

 

 

Ordering springs made easy

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Trusted in ergonomic and medical devices

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ERGONOMIC EQUIPMENT

Lesjöfors in Hollywood

Explore our long-standing relationship with Easyrig and our involvement in the development of products that offload heavy cameras, using power springs, gas springs, tension springs and compression springs.

Read more
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MEDICAL DEVICES

Exact dosing in drug delivery devices

Learn how our power springs are used in autoinjectors, drug delivery devices & pen injectors to deliver exact dosing and high levels of safety.

Learn more

Other springs and custom solutions

Lesjöfors supplies a complete range of standard and custom products, from coil springs and wireforms to pressings and gas springs. If you have unique requirements, we also offer consultancy services, with engineers available to advise on materials, loads, and specifications. Contact us to discuss your requirements.

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  • A sleek, metallic spiral torsion spring is coiled into a spiral shape against a white background. The modern design creates a sense of precision and elegance.

    Spiral torsion springs

    Formed from strip material up to 12 mm thick, for rotational torque applications.

    Spiral torsion springs
  • Metallic coil spring, also called compression spring, on a transparent background, showcasing a shiny, helical structure.

    Compression springs

    Cylindrical springs in wire diameters of 0.03 - 80 mm.

    Compression springs

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