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Extension Springs

Custom English-Hook Extension Springs

A compact end-hook extension spring suited to small linkages and constrained connections where the attachment needs to stay close to the coil body.

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English-Hook Extension Springs manufactured by CustomSprings
Typical configurations
44
Wire diameter
0.2–5 mm
Outside diameter
1.94–42.48 mm
Free length
4.28–301.48 mm

About Custom English-Hook Extension Springs

English-hook extension springs use a compact hook form that can reduce the space taken by the end connection. They are useful in small mechanisms, but the advantage is only realized when the hook geometry follows the anchor and pull direction closely. The spring should not be twisted during installation just to make the hook reach.

Key Design Characteristics

  • Compact end geometry can reduce overall package length around a small pin or tab.
  • Hook orientation is important when both ends connect in different planes.
  • Initial tension, body rate and end deflection should be considered as separate contributors to the installed force.
  • Small hooks require careful bend radii and surface condition to avoid an unnecessary fatigue hotspot.

What to Specify for a Custom Quote

  • Wire diameter, body diameter and body length
  • Installed and maximum working lengths
  • Initial tension or starting load and final working load
  • Hook size, opening and orientation at both ends
  • Anchor details, travel path, cycles, material and quantity

Manufacturing Review

A drawing should show the end form at a larger scale than the spring body. This makes the hook opening, tangent point and plane measurable and avoids using free length as the only acceptance criterion.

Common Assembly Roles

  • Small control linkages
  • Compact latch returns
  • OEM springs where end space is limited

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
SE-100-0047-0287-0519 1 mm 4.74 mm 2.74 mm 28.69 mm 9.756 301 Stainless Steel 16.9 66.2
SE-020-0026-0144-0479 0.2 mm 2.56 mm 2.16 mm 14.44 mm 0.011 Phosphor Bronze (QSn4-0.3) 56.6 0.06
SE-120-0069-0384-0446 1.2 mm 6.92 mm 4.52 mm 38.41 mm 5.03 316 Stainless Steel 19 44.11
SE-060-0043-0256-0424 0.6 mm 4.26 mm 3.06 mm 25.56 mm 0.829 Inconel X-750 31.5 4.87
SE-120-0132-0582-0464 1.2 mm 13.25 mm 10.85 mm 58.25 mm 0.295 304 Stainless Steel 34.6 5.05
SE-500-0287-3015-0473 5 mm 28.67 mm 18.67 mm 301.48 mm 9.161 65Mn Spring Steel 50.8 442.26
SE-180-0148-0375-0545 1.8 mm 14.77 mm 11.17 mm 37.48 mm 6.091 Oil-Tempered Spring Wire (SWO) 7.8 38.29
SE-400-0364-1006-0506 4 mm 36.43 mm 28.43 mm 100.63 mm 4.559 316 Stainless Steel 14.2 97.2
SE-020-0023-0043-0533 0.2 mm 2.3 mm 1.9 mm 4.28 mm 0.192 Music Wire (SWP-B) 8.9 0.51
SE-150-0077-0574-0543 1.5 mm 7.66 mm 4.66 mm 57.39 mm 8.226 65Mn Spring Steel 26 105.04
SE-100-0119-0388-0454 1 mm 11.9 mm 9.9 mm 38.82 mm 0.223 301 Stainless Steel 29.8 2.23
SE-120-0139-0544-0423 1.2 mm 13.86 mm 11.46 mm 54.4 mm 0.282 301 Stainless Steel 31.3 3.56
SE-250-0156-1393-0466 2.5 mm 15.62 mm 10.62 mm 139.28 mm 3.293 304 Stainless Steel 45.3 86.97
SE-100-0086-0231-0546 1 mm 8.64 mm 6.64 mm 23.12 mm 1.476 316 Stainless Steel 13.1 5.38
SE-150-0118-0991-0579 1.5 mm 11.83 mm 8.83 mm 99.09 mm 0.757 316 Stainless Steel 52.3 18.9
SE-030-0032-0113-0453 0.3 mm 3.22 mm 2.62 mm 11.34 mm 0.093 316 Stainless Steel 30.3 0.25
SE-200-0183-0770-0534 2 mm 18.34 mm 14.34 mm 77.03 mm 1.134 316 Stainless Steel 27.9 20.08
SE-030-0033-0079-0493 0.3 mm 3.3 mm 2.7 mm 7.89 mm 0.173 Oil-Tempered Spring Wire (SWO) 17.1 0.65
SE-080-0090-0509-0542 0.8 mm 8.98 mm 7.38 mm 50.93 mm 0.153 Music Wire (SWP-A) 48.6 2.29
SE-200-0230-0710-0578 2 mm 23.04 mm 19.04 mm 70.99 mm 0.689 316 Stainless Steel 21.5 12.11
SE-120-0084-0491-0490 1.2 mm 8.42 mm 6.02 mm 49.06 mm 1.584 301 Stainless Steel 30 12.69
SE-060-0044-0410-0509 0.6 mm 4.45 mm 3.25 mm 40.97 mm 0.206 Phosphor Bronze (QSn4-0.3) 56.5 2.56
SE-080-0068-0354-0459 0.8 mm 6.81 mm 5.21 mm 35.35 mm 0.563 Music Wire (SWP-A) 33.2 3.23
SE-020-0030-0119-0566 0.2 mm 3.01 mm 2.61 mm 11.88 mm 0.014 301 Stainless Steel 44.6 0.05
SE-500-0231-1164-0451 5 mm 23.1 mm 13.1 mm 116.36 mm 40.539 Beryllium Copper (QBe2) 15.6 1074.41
SE-020-0019-0114-0573 0.2 mm 1.94 mm 1.54 mm 11.45 mm 0.033 Phosphor Bronze (QSn4-0.3) 47.3 0.19
SE-300-0159-0898-0480 3 mm 15.93 mm 9.93 mm 89.83 mm 20.788 60Si2MnA Spring Steel 17.8 244.82
SE-250-0156-0621-0434 2.5 mm 15.55 mm 10.55 mm 62.06 mm 9.78 316 Stainless Steel 15.5 145.27
SE-300-0374-0701-0560 3 mm 37.36 mm 31.36 mm 70.13 mm 1.517 Inconel X-750 13 25.31
SE-200-0175-0715-0549 2 mm 17.54 mm 13.54 mm 71.53 mm 1.687 316 Stainless Steel 21.8 16.73
SE-180-0076-0861-0518 1.8 mm 7.55 mm 3.95 mm 86.09 mm 15.912 Music Wire (SWP-A) 34.4 280.2
SE-400-0397-2198-0522 4 mm 39.67 mm 31.67 mm 219.82 mm 1.344 Music Wire (SWP-B) 41.6 52.91
SE-030-0035-0118-0429 0.3 mm 3.5 mm 2.9 mm 11.76 mm 0.043 Phosphor Bronze (QSn4-0.3) 29.6 0.17
SE-050-0027-0128-0576 0.5 mm 2.74 mm 1.74 mm 12.75 mm 4.224 65Mn Spring Steel 13 14.73
SE-300-0327-0826-0477 3 mm 32.74 mm 26.74 mm 82.55 mm 2.055 Inconel X-750 14.8 33.08
SE-200-0167-0524-0589 2 mm 16.66 mm 12.66 mm 52.43 mm 2.592 304 Stainless Steel 16.9 18.62
SE-080-0098-0260-0496 0.8 mm 9.8 mm 8.2 mm 25.95 mm 0.226 60Si2MnA Spring Steel 24.6 1.66
SE-040-0043-0068-0567 0.4 mm 4.29 mm 3.49 mm 6.75 mm 0.591 Music Wire (SWP-B) 7.3 1.64
SE-200-0207-0943-0525 2 mm 20.71 mm 16.71 mm 94.33 mm 0.738 Carbon Spring Steel Wire (SWC) 32.5 16.25
SE-400-0425-0793-0484 4 mm 42.48 mm 34.48 mm 79.28 mm 2.567 Beryllium Copper (QBe2) 10.5 37.18
SE-050-0052-0208-0463 0.5 mm 5.22 mm 4.22 mm 20.8 mm 0.097 Phosphor Bronze (QSn4-0.3) 31.4 0.46
SE-040-0020-0093-0433 0.4 mm 1.99 mm 1.19 mm 9.27 mm 4.952 Oil-Tempered Spring Wire (SWO) 12.7 10.29
SE-060-0059-0362-0536 0.6 mm 5.92 mm 4.72 mm 36.21 mm 0.184 Carbon Spring Steel Wire (SWC) 46 1.65
SE-500-0328-2228-0503 5 mm 32.84 mm 22.84 mm 222.77 mm 6.901 301 Stainless Steel 36.2 261.07

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

Engineering Data

Typical Dimensions & Design Data

Use these data points to compare geometry, material and working parameters when defining your custom spring. Final values are reviewed and confirmed for the actual assembly before production.

ConfigurationData typeKey parametersMaterial / basis
Engineering Data 01 Engineering Data
  • Reference parameter: English / Machine-Hook Extension Spring
  • Data use: Engineering reference
 Per drawing / published type
Engineering Data 02 Manufacturing Range
  • Reference parameter: 0.0508 mm
  • Reference parameter: 15.875 mm
  • Status: Custom made
 Common spring steels, stainless steels and alloys
Engineering Data 03 Design Input
  • Key field 1: Wire diameter
  • Key field 2: Body OD
  • Key field 3: Free length / initial tension
 Per drawing
Typical Configuration 04Data point Typical Configuration
  • Outside diameter: 4.7 mm
  • Wire diameter: 0.4 mm
  • Free length: 50 mm
  • Spring rate: 0.027 N/mm
  • Maximum Length: 241.3 mm
  • Maximum force: 5.59 N
 Stainless steel
Typical Configuration 05Data point Typical Configuration
  • Outside diameter: 4.7 mm
  • Wire diameter: 0.4 mm
  • Free length: 57 mm
  • Spring rate: 0.027 N/mm
  • Maximum Length: 284.7 mm
  • Maximum force: 6.64 N
 Music wire
Typical Configuration 06Data point Typical Configuration
  • Outside diameter: 4.7 mm
  • Wire diameter: 0.45 mm
  • Free length: 41 mm
  • Spring rate: 0.074 N/mm
  • Maximum Length: 154.2 mm
  • Maximum force: 9.25 N
 Music wire

Design note: dimensions, force / torque, material, tolerances, fatigue life and compliance are finalized against your drawing and operating conditions during quotation.

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

High-strength carbon wire works well in protected mechanisms; stainless grades are common when the small spring is exposed to humidity, handling or cleaning. The chosen wire must also tolerate the compact hook forming operation.

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.

Stainless Steel Spring MaterialsSelection guide Carbon & Alloy Spring SteelsSelection 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 316 Stainless Steel Extension Springs Engineering Data 9 matching english-hook extension springs data rows are included in the category. Material data 301 Stainless Steel Extension Springs Engineering Data 6 matching english-hook extension springs data rows are included in the category. Material data Phosphor Bronze (QSn4-0.3) Extension Springs Engineering Data 5 matching english-hook extension springs data rows are included in the category. Wire diameter 0.2 mm Extension Springs Engineering Data 4 matching english-hook extension springs data rows are included in the category. Wire diameter 0.8 mm Extension Springs Engineering Data 3 matching english-hook extension springs data rows are included in the category. Wire diameter 1.8 mm Extension Springs Engineering Data 2 matching english-hook extension springs data rows are included in the category.

Compare Designs

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

Round-Hook Extension Springs manufactured by CustomSprings

Extension Springs

Round-Hook Extension Springs

An extension spring with simple round hooks for straightforward pin, hole or tab connections where the pull direction stays close to the spring axis.

German-Hook Extension Springs manufactured by CustomSprings

Extension Springs

German-Hook Extension Springs

An extension spring with a compact German-style hook profile used when the connection geometry needs more control than a simple round loop provides.

Offset-Hook Extension Springs manufactured by CustomSprings

Extension Springs

Offset-Hook Extension Springs

An extension spring with an intentionally offset connection point for assemblies where the anchors do not line up with the coil centerline.

Product Questions

English-Hook Extension Springs FAQ

Does the English hook change the spring rate?

The coil body still controls most of the rate, but the end contributes compliance and changes overall length. For close load tolerances, the complete spring should be tested at defined lengths.

What drawing view matters most for the hook?

At least two views are helpful whenever the hook has a defined plane or offset. A single side view can hide the orientation needed for assembly.

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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