Engineering Tools · Spring Pin Reference
Coiled Spring Pin Size Chart — ISO 8748 / GB/T 879.3 Heavy, ISO 8750 / 879.4 Standard and ISO 8751 / 879.5 Light Duty
A coiled spring pin is strip steel coiled into a spiral tube with a continuous wall, so the load is taken all round once it is pressed in. This page sets ISO 8748 / GB/T 879.3 heavy duty, ISO 8750 / GB/T 879.4 standard duty and ISO 8751 / GB/T 879.5 light duty side by side: d1 from 0.8–20 mm, 40 sizes and 101 cut-length steps lc. All three parts split the shear load into a and b rows, and the hole tolerance has its one exception — H10 for ISO 8750 / GB/T 879.4 at d1 ≤ 1.2 mm.
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GB/T 879.3-2018 — Coiled heavy duty
Modified adoption of ISO 8748:2007
Rows are dimension elements, columns are nominal diameters d1. d2 = slot root diameter; a = slot width; s = pin wall thickness; load in kN.
| d1 nominal | d1 max (before insertion) | d1 min (before insertion) | d2 (before insertion) | a max | Minimum shear load (double shear) a | Minimum shear load (double shear) b | s (wall thickness) |
|---|---|---|---|---|---|---|---|
| 1.5 | 1.71 | 1.61 | 1.4 | 0.5 | 1.9 | 1.45 | 0.17 |
| 2 | 2.21 | 2.11 | 1.9 | 0.7 | 3.5 | 2.5 | 0.22 |
| 2.5 | 2.73 | 2.62 | 2.4 | 0.7 | 5.5 | 3.8 | 0.28 |
| 3 | 3.25 | 3.12 | 2.9 | 0.9 | 7.6 | 5.7 | 0.33 |
| 3.5 | 3.79 | 3.64 | 3.4 | 1 | 10 | 7.6 | 0.39 |
| 4 | 4.3 | 4.15 | 3.9 | 1.1 | 13.5 | 10 | 0.45 |
| 5 | 5.35 | 5.15 | 4.85 | 1.3 | 20 | 15.5 | 0.56 |
| 6 | 6.4 | 6.18 | 5.85 | 1.5 | 30 | 23 | 0.67 |
| 8 | 8.55 | 8.25 | 7.8 | 2 | 53 | 41 | 0.9 |
| 10 | 10.65 | 10.3 | 9.75 | 2.5 | 84 | 64 | 1.1 |
| 12 | 12.75 | 12.35 | 11.7 | 3 | 120 | 91 | 1.3 |
| 14 | 14.85 | 14.4 | 13.6 | 3.5 | 165 | — | 1.6 |
| 16 | 16.9 | 16.4 | 15.6 | 4 | 210 | — | 1.8 |
| 20 | 21 | 20.4 | 19.6 | 4.5 | 340 | — | 2.2 |
Row a applies to products in steel and martensitic stainless steel; row b applies to austenitic stainless steel. A dash means the standard does not specify that step.
GB/T 879.4-2018 — Coiled standard duty
Modified adoption of ISO 8750:2007
Rows are dimension elements, columns are nominal diameters d1. d2 = slot root diameter; a = slot width; s = pin wall thickness; load in kN.
| d1 nominal | d1 max (before insertion) | d1 min (before insertion) | d2 (before insertion) | a max | Minimum shear load (double shear) a | Minimum shear load (double shear) b | s (wall thickness) |
|---|---|---|---|---|---|---|---|
| 0.8 | 0.91 | 0.85 | 0.75 | 0.3 | 0.4 | 0.3 | 0.07 |
| 1 | 1.15 | 1.05 | 0.95 | 0.3 | 0.6 | 0.45 | 0.08 |
| 1.2 | 1.35 | 1.25 | 1.15 | 0.4 | 0.9 | 0.65 | 0.1 |
| 1.5 | 1.73 | 1.62 | 1.4 | 0.5 | 1.45 | 1.05 | 0.13 |
| 2 | 2.25 | 2.13 | 1.9 | 0.7 | 2.5 | 1.9 | 0.17 |
| 2.5 | 2.78 | 2.65 | 2.4 | 0.7 | 3.9 | 2.9 | 0.21 |
| 3 | 3.3 | 3.15 | 2.9 | 0.9 | 5.5 | 4.2 | 0.25 |
| 3.5 | 3.84 | 3.67 | 3.4 | 1 | 7.5 | 5.7 | 0.29 |
| 4 | 4.4 | 4.2 | 3.9 | 1.1 | 9.6 | 7.6 | 0.33 |
| 5 | 5.5 | 5.25 | 4.85 | 1.3 | 15 | 11.5 | 0.42 |
| 6 | 6.5 | 6.25 | 5.85 | 1.5 | 22 | 16.8 | 0.5 |
| 8 | 8.63 | 8.3 | 7.8 | 2 | 39 | 30 | 0.67 |
| 10 | 10.8 | 10.35 | 9.75 | 2.5 | 62 | 48 | 0.84 |
| 12 | 12.85 | 12.4 | 11.7 | 3 | 89 | 67 | 1 |
| 14 | 14.95 | 14.45 | 13.6 | 3.5 | 120 | — | 1.2 |
| 16 | 17 | 16.45 | 15.6 | 4 | 155 | — | 1.3 |
| 20 | 21.1 | 20.4 | 19.6 | 4.5 | 250 | — | 1.7 |
Row a applies to products in steel and martensitic stainless steel; row b applies to austenitic stainless steel. A dash means the standard does not specify that step.
GB/T 879.5-2018 — Coiled light duty
Modified adoption of ISO 8751:2007
Rows are dimension elements, columns are nominal diameters d1. d2 = slot root diameter; a = slot width; s = pin wall thickness; load in kN.
| d1 nominal | d1 max (before insertion) | d1 min (before insertion) | d2 (before insertion) | a max | Minimum shear load (double shear) a | Minimum shear load (double shear) b | s (wall thickness) |
|---|---|---|---|---|---|---|---|
| 1.5 | 1.75 | 1.62 | 1.4 | 0.5 | 0.8 | 0.65 | 0.08 |
| 2 | 2.28 | 2.13 | 1.9 | 0.7 | 1.5 | 1.1 | 0.11 |
| 2.5 | 2.82 | 2.65 | 2.4 | 0.7 | 2.3 | 1.8 | 0.14 |
| 3 | 3.35 | 3.15 | 2.9 | 0.9 | 3.3 | 2.5 | 0.17 |
| 3.5 | 3.87 | 3.67 | 3.4 | 1 | 4.5 | 3.4 | 0.19 |
| 4 | 4.45 | 4.2 | 3.9 | 1.1 | 5.7 | 4.4 | 0.22 |
| 5 | 5.5 | 5.2 | 4.85 | 1.3 | 9 | 7 | 0.28 |
| 6 | 6.55 | 6.25 | 5.85 | 1.5 | 13 | 10 | 0.33 |
| 8 | 8.65 | 8.3 | 7.8 | 2 | 23 | 18 | 0.45 |
Row a applies to products in steel and martensitic stainless steel; row b applies to austenitic stainless steel. A dash means the standard does not specify that step.
Cut-length series lc and limits (mm)
| lc nominal | lc min | lc max | Parts on this page |
|---|---|---|---|
| 4 | 3.75 | 4.25 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 5 | 4.75 | 5.25 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 6 | 5.75 | 6.25 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 8 | 7.75 | 8.25 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 10 | 9.75 | 10.25 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 12 | 11.5 | 12.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 14 | 13.5 | 14.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 16 | 15.5 | 16.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 18 | 17.5 | 18.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 20 | 19.5 | 20.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 22 | 21.5 | 22.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 24 | 23.5 | 24.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 26 | 25.5 | 26.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 28 | 27.5 | 28.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 30 | 29.5 | 30.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 32 | 31.5 | 32.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 35 | 34.5 | 35.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 40 | 39.5 | 40.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 45 | 44.5 | 45.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 50 | 49.5 | 50.5 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 55 | 54.25 | 55.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 60 | 59.25 | 60.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 65 | 64.25 | 65.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 70 | 69.25 | 70.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 75 | 74.25 | 75.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 80 | 79.25 | 80.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 85 | 84.25 | 85.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 90 | 89.25 | 90.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 95 | 94.25 | 95.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 100 | 99.25 | 100.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 120 | 119.25 | 120.75 | Coiled heavy duty / Coiled standard duty / Coiled light duty |
| 140 | 139.25 | 140.75 | Coiled heavy duty / Coiled standard duty |
| 160 | 159.25 | 160.75 | Coiled heavy duty / Coiled standard duty |
| 180 | 179.25 | 180.75 | Coiled heavy duty / Coiled standard duty |
| 200 | 199.25 | 200.75 | Coiled heavy duty / Coiled standard duty |
lc is the nominal cut length; min and max are the lower and upper limits fixed by the standard. Above 200 mm nominal length the series steps by 20 mm.
Same nominal diameter, side by side
For the nominal diameters all three parts cover, wall thickness s and the a / b minimum double shear load are shown step by step. A dash means the standard does not specify the b value at that step.
| d1 (mm) | GB/T 879.3-2018 — Coiled heavy duty | GB/T 879.4-2018 — Coiled standard duty | GB/T 879.5-2018 — Coiled light duty |
|---|---|---|---|
| 1.5 | s 0.17 mma 1.9 kN / b 1.45 kN | s 0.13 mma 1.45 kN / b 1.05 kN | s 0.08 mma 0.8 kN / b 0.65 kN |
| 2 | s 0.22 mma 3.5 kN / b 2.5 kN | s 0.17 mma 2.5 kN / b 1.9 kN | s 0.11 mma 1.5 kN / b 1.1 kN |
| 2.5 | s 0.28 mma 5.5 kN / b 3.8 kN | s 0.21 mma 3.9 kN / b 2.9 kN | s 0.14 mma 2.3 kN / b 1.8 kN |
| 3 | s 0.33 mma 7.6 kN / b 5.7 kN | s 0.25 mma 5.5 kN / b 4.2 kN | s 0.17 mma 3.3 kN / b 2.5 kN |
| 3.5 | s 0.39 mma 10 kN / b 7.6 kN | s 0.29 mma 7.5 kN / b 5.7 kN | s 0.19 mma 4.5 kN / b 3.4 kN |
| 4 | s 0.45 mma 13.5 kN / b 10 kN | s 0.33 mma 9.6 kN / b 7.6 kN | s 0.22 mma 5.7 kN / b 4.4 kN |
| 5 | s 0.56 mma 20 kN / b 15.5 kN | s 0.42 mma 15 kN / b 11.5 kN | s 0.28 mma 9 kN / b 7 kN |
| 6 | s 0.67 mma 30 kN / b 23 kN | s 0.5 mma 22 kN / b 16.8 kN | s 0.33 mma 13 kN / b 10 kN |
| 8 | s 0.9 mma 53 kN / b 41 kN | s 0.67 mma 39 kN / b 30 kN | s 0.45 mma 23 kN / b 18 kN |
Basis & Disclosed Assumptions
Where the numbers come from
- Dimensions and shear loads are taken cell by cell from Table 1 and the sub-table below Table 1 of GB/T 879.3-2018, GB/T 879.4-2018 and GB/T 879.5-2018. This page and the family index share one constant, so every figure can be recalculated.
- d1 max, d1 min and d2 are pre-insertion values: the pin is larger than the hole before it is pressed in and holds by elastic recovery, so the limit sizes sit above the nominal value.
- The shear load is split into row a (steel and martensitic stainless steel) and row b (austenitic stainless steel). The b values are lower than the a values and the standard leaves the larger diameters unspecified, shown here as a dash.
- a is the width of the coiled opening (max) and s is the tube wall; the convention matches the slotted parts (slot width plus wall) but every value comes from the part's own Table 1.
Scope & limits
- Nominal hole diameter equals d1 with tolerance zone H12 to ISO 286-2 / GB/T 1800.2 in the normal case. ISO 8750 / GB/T 879.4 is the exception: H12 for d1 ≥ 1.5 mm and H10 for d1 ≤ 1.2 mm.
- Length limits are banded: ±0.25 mm for lc ≤ 10 mm, ±0.5 mm for 12–50 mm and ±0.75 mm for 55–200 mm (the lc series of ISO 8751 / GB/T 879.5 stops at 120 mm).
- The standard requires that the slot must not close completely when the pin is fitted in the smallest permitted hole; the same applies to coiled pins.
- No weight data in this family: the coiled parts tabulate no mass and this site offers no weight calculator for them.
References
- GB/T 879.3-2018 Spring-type straight pins — Coiled — Heavy duty, Table 1 (National Public Service Platform for Standards Information)
- GB/T 879.4-2018 Spring-type straight pins — Coiled — Standard duty, Table 1
- GB/T 879.5-2018 Spring-type straight pins — Coiled — Light duty, Table 1
- GB/T 1800.2-2020 Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes: source of H12 / H10
Cite this chart
YAXIIO. Coiled Spring Pin Size Chart — ISO 8748 / GB/T 879.3 Heavy, ISO 8750 / 879.4 Standard and ISO 8751 / 879.5 Light Duty. https://www.yaxiio.com/en/tools/spring-pin-chart/coiled (accessed 2026-10-29).
Free to cite and embed — attribution required: “YAXIIO” + a link to this page.
FAQ
How do the three coiled parts differ at the same d1?
Take d1 = 8 mm, the largest nominal diameter all three cover: wall thickness s is 0.9 mm for heavy duty, 0.67 mm for standard duty and 0.45 mm for light duty; the minimum double shear load in row a is 53 kN, 39 kN and 23 kN respectively (row b: 41 / 30 / 18 kN). The higher the load class, the more material the same d1 carries, and the greater the press-in force and radial force on the hole wall.
Should I use row a or row b?
Pick the row that matches the pin material: row a for steel and martensitic stainless steel, row b for austenitic stainless steel. At the same d1 the b value is lower than the a value, and at the larger diameters the standard specifies no b value at all, shown here as a dash. Do not substitute the a value in those cells — the lower material strength is real, and the fix for more capacity is a larger diameter or a steel pin.
When does the H10 hole of ISO 8750 / GB/T 879.4 apply?
Only at d1 ≤ 1.2 mm in ISO 8750 / GB/T 879.4 coiled standard duty: the hole is H10 there, while d1 ≥ 1.5 mm stays H12. At the smallest diameters the pin body is thin and has little compression to give, so the tighter zone preserves enough radial grip after press-in. Coiled heavy duty and light duty have no such exception and stay H12 throughout.
Related References
Disclaimer: this chart provides engineering reference data for selection and quotation only; it is not a design basis or an acceptance standard.