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Torsion Springs

Custom Single-Leg Torsion Springs

A compact torsion-spring arrangement with one main working arm and the opposite end retained close to the coil for one-sided rotary return.

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Single-Leg Torsion Springs manufactured by CustomSprings
Typical configurations
43
Wire diameter
0.3–6 mm
Outside diameter
2.64–84.3 mm
Free length
1.84–125.31 mm

About Custom Single-Leg Torsion Springs

Single-leg torsion springs are useful when only one long external arm is needed and the fixed end can be captured in a hole, slot or pocket near the coil. The retained end is still part of the load path, so its seating and freedom to move have to be shown clearly on the assembly drawing.

Key Design Characteristics

  • The retained end must be prevented from rotating in a repeatable way without being crushed or sharply bent.
  • The active leg contact radius determines how spring torque becomes force at the moving part.
  • Coil clearance on the pin or shaft changes as the spring winds.
  • Free position, installed preload and maximum angle should all be defined.

What to Specify for a Custom Quote

  • Wire diameter, coil ID, body width and shaft size
  • Geometry of the retained end and the feature that captures it
  • Working-leg length, free angle and operating angles
  • Torque requirement and any installed preload
  • Winding direction, cycle target, environment and quantity

Manufacturing Review

Sample validation should use a fixture that reproduces both the retained end and the active leg contact point. Otherwise measured torque may not represent the real assembly.

Common Assembly Roles

  • One-sided lever return
  • Compact selector and latch mechanisms
  • Hinged parts where the fixed end can be hidden near the pivot

Product Data

Typical Spring Configurations

Use these data points to compare practical starting dimensions and material options. Final production specifications are confirmed against your drawing and working conditions.

ModelWire dia.ODIDFree lengthRateMaterialCoilsMax load
ST-040-0071-0073-0720 0.4 mm 7.14 mm 6.34 mm 7.26 mm 0.006 Phosphor Bronze (QSn4-0.3) 17.5 0.58
ST-120-0175-0065-0684 1.2 mm 17.52 mm 15.12 mm 6.5 mm 1.286 316 Stainless Steel 5.2 42.7
ST-100-0066-0159-0700 1 mm 6.58 mm 4.58 mm 15.91 mm 0.633 60Si2MnA Spring Steel 15.9 44.96
ST-250-0313-0258-0659 2.5 mm 31.26 mm 26.26 mm 25.84 mm 4.694 Beryllium Copper (QBe2) 10.1 514.01
ST-060-0034-0109-0661 0.6 mm 3.37 mm 2.17 mm 10.9 mm 0.076 Phosphor Bronze (QSn4-0.3) 17.3 12.79
ST-030-0054-0026-0646 0.3 mm 5.42 mm 4.82 mm 2.65 mm 0.01 301 Stainless Steel 8.1 0.86
ST-180-0086-0144-0676 1.8 mm 8.64 mm 5.04 mm 14.42 mm 11.785 Inconel X-750 7.6 1746.54
ST-100-0066-0128-0594 1 mm 6.58 mm 4.58 mm 12.81 mm 0.419 Phosphor Bronze (QSn4-0.3) 12 22.48
ST-400-0450-0687-0626 4 mm 45 mm 37 mm 68.68 mm 21.131 65Mn Spring Steel 16.6 1094.57
ST-050-0066-0035-0714 0.5 mm 6.57 mm 5.57 mm 3.52 mm 0.084 Music Wire (SWP-A) 6.9 7.86
ST-600-0684-0308-0606 6 mm 68.39 mm 56.39 mm 30.76 mm 247.403 Inconel X-750 4.9 37926.89
ST-150-0141-0213-0658 1.5 mm 14.06 mm 11.06 mm 21.3 mm 1.69 65Mn Spring Steel 13.4 205.82
ST-200-0126-0342-0652 2 mm 12.6 mm 8.6 mm 34.19 mm 5.018 60Si2MnA Spring Steel 16.9 613.65
ST-300-0269-0405-0674 3 mm 26.92 mm 20.92 mm 40.49 mm 7.373 Phosphor Bronze (QSn4-0.3) 12.9 999.1
ST-100-0128-0089-0633 1 mm 12.76 mm 10.76 mm 8.86 mm 0.576 65Mn Spring Steel 8.3 18.3
ST-400-0278-0183-0596 4 mm 27.82 mm 19.82 mm 18.3 mm 149.334 Inconel X-750 4.2 5614.98
ST-300-0382-0124-0682 3 mm 38.15 mm 32.15 mm 12.41 mm 15.787 Phosphor Bronze (QSn4-0.3) 4.1 896.72
ST-400-0226-0156-0689 4 mm 22.62 mm 14.62 mm 15.65 mm 195.575 316 Stainless Steel 3.7 16721.66
ST-180-0166-0341-0701 1.8 mm 16.65 mm 13.05 mm 34.1 mm 2.135 Music Wire (SWP-B) 18.6 241.48
ST-250-0148-0476-0693 2.5 mm 14.81 mm 9.81 mm 47.56 mm 4.844 Phosphor Bronze (QSn4-0.3) 18.4 493.14
ST-060-0045-0077-0667 0.6 mm 4.48 mm 3.28 mm 7.72 mm 0.138 304 Stainless Steel 12.7 13.68
ST-600-0278-0854-0593 6 mm 27.81 mm 15.81 mm 85.39 mm 220.25 304 Stainless Steel 14.2 27707.44
ST-500-0630-0440-0702 5 mm 62.98 mm 52.98 mm 44.03 mm 45.888 Beryllium Copper (QBe2) 8.2 6823.49
ST-400-0294-0619-0709 4 mm 29.41 mm 21.41 mm 61.94 mm 38.502 60Si2MnA Spring Steel 14.7 1986.7
ST-250-0205-0364-0631 2.5 mm 20.53 mm 15.53 mm 36.38 mm 9.083 Carbon Spring Steel Wire (SWC) 13.4 636.71
ST-120-0165-0106-0673 1.2 mm 16.46 mm 14.06 mm 10.56 mm 0.954 Carbon Spring Steel Wire (SWC) 8 124.43
ST-040-0026-0042-0715 0.4 mm 2.64 mm 1.84 mm 4.16 mm 0.062 Music Wire (SWP-B) 10.3 6.67
ST-600-0843-1253-0713 6 mm 84.3 mm 72.3 mm 125.31 mm 47.684 Music Wire (SWP-A) 19.5 7257.51
ST-200-0204-0321-0664 2 mm 20.43 mm 16.43 mm 32.12 mm 2.91 316 Stainless Steel 15.7 186.85
ST-040-0070-0044-0599 0.4 mm 7.01 mm 6.21 mm 4.4 mm 0.02 Music Wire (SWP-A) 10.9 2.69
ST-200-0168-0255-0660 2 mm 16.76 mm 12.76 mm 25.53 mm 4.992 Music Wire (SWP-B) 12.2 305.48
ST-300-0248-0572-0665 3 mm 24.78 mm 18.78 mm 57.17 mm 11.479 60Si2MnA Spring Steel 18.2 1878.03
ST-300-0359-0618-0619 3 mm 35.91 mm 29.91 mm 61.85 mm 6.576 304 Stainless Steel 19.7 1075.14
ST-050-0056-0018-0694 0.5 mm 5.62 mm 4.62 mm 1.84 mm 0.21 Inconel X-750 3.4 9.2
ST-180-0113-0315-0654 1.8 mm 11.34 mm 7.74 mm 31.46 mm 3.746 65Mn Spring Steel 16.5 180.21
ST-400-0531-0742-0711 4 mm 53.11 mm 45.11 mm 74.19 mm 10.641 Beryllium Copper (QBe2) 17.1 1439.72
ST-180-0100-0124-0634 1.8 mm 9.96 mm 6.36 mm 12.36 mm 10.106 304 Stainless Steel 6.7 1242.03
ST-180-0138-0182-0710 1.8 mm 13.82 mm 10.22 mm 18.18 mm 4.906 Music Wire (SWP-A) 10 310.08
ST-100-0044-0113-0618 1 mm 4.41 mm 2.41 mm 11.33 mm 1.378 316 Stainless Steel 11.2 184.11
ST-060-0069-0101-0679 0.6 mm 6.94 mm 5.74 mm 10.11 mm 0.077 Inconel X-750 15.5 11.01
ST-050-0030-0069-0707 0.5 mm 2.99 mm 1.99 mm 6.93 mm 0.096 316 Stainless Steel 13.8 12.04
ST-080-0046-0050-0623 0.8 mm 4.64 mm 3.04 mm 5.03 mm 1.016 65Mn Spring Steel 5.9 142.8
ST-200-0278-0226-0616 2 mm 27.85 mm 23.85 mm 22.58 mm 3.045 301 Stainless Steel 10.7 253.62

Rate: N-mm/degree; maximum load: N-mm. Dimensions are in millimeters.

Next Design Decisions

Next Steps for Your Spring Design

Once the spring style is selected, confirm how it works in the assembly, which material suits the environment, how it will be manufactured and which dimensions and performance points should be controlled on the drawing.

Applications

Where this spring style fits

Review best-fit uses, assembly constraints and situations where another spring style may be a better choice.

View application guidance →

Materials

Choose the material for the environment

Material choice is driven by torque, angle, fatigue and environment. If the fixed end uses a tight bend or short tail, formability becomes an additional constraint.

Compare spring materials →

Manufacturing

Plan prototype and production

Review forming, heat treatment, secondary operations, inspection and the path from first samples to repeat production.

View manufacturing capabilities →

Engineering Data

Open matching engineering guides

Matching material and wire-diameter pages provide additional design data for material and size selection.

Open Spring Engineering Guide →

Material Direction

Common Material Families to Review

The links below are selection guides, not a claim that every grade is suitable for every size or load.

Carbon & Alloy Spring SteelsSelection guide Stainless Steel Spring MaterialsSelection guide Copper Alloy Spring MaterialsSelection guide Nickel & High-Temperature Spring AlloysSelection guide

Related Spring Design Guides

Review the design and measurement requirements for this spring family.

Engineering Support

Spring Engineering Guides

Use these guides to compare material, wire diameter and standard requirements before finalizing the product drawing.

Material data Phosphor Bronze (QSn4-0.3) Torsion Springs Engineering Data 6 matching single-leg torsion springs data rows are included in the category. Material data 316 Stainless Steel Torsion Springs Engineering Data 5 matching single-leg torsion springs data rows are included in the category. Material data Inconel X-750 Torsion Springs Engineering Data 5 matching single-leg torsion springs data rows are included in the category. Wire diameter 0.3 mm Torsion Springs Engineering Data 1 matching single-leg torsion springs data row are included in the category. Wire diameter 1 mm Torsion Springs Engineering Data 4 matching single-leg torsion springs data rows are included in the category. Wire diameter 2 mm Torsion Springs Engineering Data 4 matching single-leg torsion springs data rows are included in the category.

Compare Designs

Use these alternatives when the available space, connection style, travel or force direction changes.

Straight-Leg Torsion Springs manufactured by CustomSprings

Torsion Springs

Straight-Leg Torsion Springs

A torsion spring with simple straight arms for hinges, levers and pivots where both contact points can be defined directly from the coil axis.

Double-Leg Torsion Springs manufactured by CustomSprings

Torsion Springs

Double-Leg Torsion Springs

A torsion spring with two working arms used to share rotary load across a wider mechanism or provide balanced return around a common pivot.

Hairpin Springs manufactured by CustomSprings

Torsion Springs

Hairpin Springs

An open U- or hairpin-shaped spring for shallow layouts where two arms flex around a curved center rather than around a tightly wound coil body.

Product Questions

Single-Leg Torsion Springs FAQ

How should the short fixed end be retained?

Use a defined feature such as a hole or slot that stops rotation without creating a sharp notch at the wire. The retention detail should be part of the drawing.

Can the fixed end be allowed to slide?

It can in some designs, but then the spring geometry and torque curve must be evaluated with that movement included. Uncontrolled sliding can change preload.

RFQ

Send the Working Requirement

A drawing is ideal. If you do not have one yet, provide the dimensions, load or torque, travel, environment and expected quantity that matter in the assembly.

CustomSprings Engineering Catalog

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Send your dimensions, quantity and drawing for engineering review.

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