Crescent Retaining Rings for Shafts (Series 2103–5103)
Crescent retaining rings for shafts, series 2103–5103 — the shallow-arc ring that seats in a shallow groove and is inserted with pliers where a full circlip would need a deeper cut — with the collected 17-size table (rings 12 to 81): d2, d3, s, dg, b, d1, m, n and the source’s six supplementary columns.
Last updated: 2026-11
Specifications
A crescent retaining ring is the shallow-section cousin of a full external circlip: an open arc that snaps into a proportionally shallower groove on a shaft, holds assemblies axially, and removes with retaining-ring pliers. The shallower section is the point — it suits grooves cut into hardened shafts, thin sections and shoulders where a DIN 471-depth groove is not wanted. The collected table lists rings 12 through 81 — 17 sizes — with groove-side geometry (d2 with its per-size plus/minus tolerances, d3 reference, s thickness, dg, b, d1, m, n min.) plus six supplementary columns reproduced under their printed labels (FN Lbr., Fs Lbr., g, Fsg Lib., nabl min., lbs). The collected page header prints "All measurements in millimeters (mm)", yet the value scale and the 2103–5103 series numbering follow the imperial retaining-ring convention used by the inch ring pages on this site; every figure below is reproduced exactly as printed and the unit question should be confirmed at quotation.
| Standard / series | Crescent rings for shafts, series 2103–5103 (collected table covers rings 12–81) |
|---|---|
| Working principle | Shallow-arc external ring snapped axially into a shallow shaft groove; plier installation and removal |
| Units note | Collected header prints millimeters while the value scale follows the imperial series convention — figures rendered as printed; confirm at quotation |
| Column labels | FN Lbr. / Fs Lbr. / g / Fsg Lib. / nabl min. / lbs reproduced as printed — the collected table carries no unit legend |
| Row, ring 1 | ring 12 | d2 0.106 +0.0015/-0.0015 | d3 ref. 0.165 | s 0.015 +0.002/-0.002 | dg 0.102 +0.002/-0.004 | b 0.031 +0.003/-0.003 | d1 0.125 | m 0.020 +0.002/-0.000 | n min. 0.020 | FN Lbr. 45 | Fs Lbr. 86 | g 0.011 | Fsg Lib. 85 | nabl min. 80000 | lbs 0.033 |
| Row, ring 2 | ring 15 | d2 0.135 +0.0015/-0.0015 | d3 ref. 0.205 | s 0.015 +0.002/-0.002 | dg 0.131 +0.002/-0.004 | b 0.037 +0.003/-0.003 | d1 0.156 | m 0.020 +0.002/-0.000 | n min. 0.020 | FN Lbr. 55 | Fs Lbr. 102 | g 0.014 | Fsg Lib. 100 | nabl min. 75000 | lbs 0.053 |
| Row, ring 3 | ring 18 | d2 0.165 +0.0015/-0.0015 | d3 ref. 0.244 | s 0.015 +0.002/-0.002 | dg 0.161 +0.002/-0.004 | b 0.042 +0.003/-0.003 | d1 0.188 | m 0.020 +0.002/-0.000 | n min. 0.022 | FN Lbr. 70 | Fs Lbr. 132 | g 0.016 | Fsg Lib. 110 | nabl min. 73000 | lbs 0.070 |
| Row, ring 4 | ring 21 | d2 0.193 +0.0020/-0.0020 | d3 ref. 0.275 | s 0.025 +0.002/-0.002 | dg 0.187 +0.003/-0.005 | b 0.044 +0.003/-0.003 | d1 0.219 | m 0.029 +0.003/-0.000 | n min. 0.026 | FN Lbr. 100 | Fs Lbr. 264 | g 0.016 | Fsg Lib. 260 | nabl min. 71000 | lbs 0.132 |
| Row, ring 5 | ring 23 | d2 0.208 +0.0020/-0.0020 | d3 ref. 0.295 | s 0.025 +0.002/-0.002 | dg 0.203 +0.003/-0.005 | b 0.046 +0.004/-0.004 | d1 0.236 | m 0.029 +0.003/-0.000 | n min. 0.028 | FN Lbr. 115 | Fs Lbr. 284 | g 0.017 | Fsg Lib. 275 | nabl min. 62000 | lbs 0.154 |
| Row, ring 6 | ring 25 | d2 0.220 +0.0020/-0.0020 | d3 ref. 0.311 | s 0.025 +0.002/-0.002 | dg 0.211 +0.003/-0.005 | b 0.050 +0.004/-0.004 | d1 0.250 | m 0.029 +0.003/-0.000 | n min. 0.030 | FN Lbr. 130 | Fs Lbr. 294 | g 0.018 | Fsg Lib. 290 | nabl min. 60000 | lbs 0.183 |
| Row, ring 7 | ring 28 | d2 0.247 +0.0020/-0.0020 | d3 ref. 0.346 | s 0.025 +0.002/-0.002 | dg 0.242 +0.003/-0.005 | b 0.051 +0.004/-0.004 | d1 0.281 | m 0.029 +0.003/-0.000 | n min. 0.034 | FN Lbr. 165 | Fs Lbr. 335 | g 0.016 | Fsg Lib. 310 | nabl min. 56000 | lbs 0.176 |
| Row, ring 8 | ring 31 | d2 0.276 +0.0020/-0.0020 | d3 ref. 0.376 | s 0.025 +0.002/-0.002 | dg 0.270 +0.003/-0.005 | b 0.053 +0.004/-0.004 | d1 0.312 | m 0.029 +0.003/-0.000 | n min. 0.036 | FN Lbr. 200 | Fs Lbr. 376 | g 0.018 | Fsg Lib. 310 | nabl min. 52000 | lbs 0.264 |
| Row, ring 9 | ring 37 | d2 0.335 +0.0020/-0.0020 | d3 ref. 0.448 | s 0.025 +0.002/-0.002 | dg 0.328 +0.003/-0.005 | b 0.060 +0.004/-0.004 | d1 0.375 | m 0.029 +0.003/-0.000 | n min. 0.040 | FN Lbr. 270 | Fs Lbr. 447 | g 0.020 | Fsg Lib. 310 | nabl min. 43000 | lbs 0.297 |
| Row, ring 10 | ring 40 | d2 0.364 +0.0020/-0.0020 | d3 ref. 0.486 | s 0.025 +0.002/-0.002 | dg 0.359 +0.003/-0.005 | b 0.063 +0.004/-0.004 | d1 0.406 | m 0.029 +0.003/-0.000 | n min. 0.042 | FN Lbr. 300 | Fs Lbr. 487 | g 0.021 | Fsg Lib. 310 | nabl min. 40000 | lbs 0.374 |
| Row, ring 11 | ring 43 | d2 0.393 +0.0020/-0.0020 | d3 ref. 0.517 | s 0.025 +0.002/-0.002 | dg 0.386 +0.003/-0.005 | b 0.065 +0.004/-0.004 | d1 0.438 | m 0.029 +0.003/-0.000 | n min. 0.044 | FN Lbr. 350 | Fs Lbr. 528 | g 0.022 | Fsg Lib. 310 | nabl min. 31000 | lbs 0.352 |
| Row, ring 12 | ring 50 | d2 0.450 +0.0030/-0.0030 | d3 ref. 0.581 | s 0.035 +0.002/-0.002 | dg 0.441 +0.006/-0.006 | b 0.070 +0.005/-0.005 | d1 0.500 | m 0.039 +0.003/-0.000 | n min. 0.050 | FN Lbr. 450 | Fs Lbr. 842 | g 0.023 | Fsg Lib. 610 | nabl min. 25000 | lbs 0.733 |
| Row, ring 13 | ring 56 | d2 0.507 +0.0030/-0.0030 | d3 ref. 0.653 | s 0.035 +0.002/-0.002 | dg 0.497 +0.006/-0.006 | b 0.078 +0.005/-0.005 | d1 0.562 | m 0.039 +0.003/-0.000 | n min. 0.056 | FN Lbr. 550 | Fs Lbr. 944 | g 0.025 | Fsg Lib. 610 | nabl min. 22000 | lbs 0.836 |
| Row, ring 14 | ring 62 | d2 0.563 +0.0030/-0.0030 | d3 ref. 0.715 | s 0.035 +0.002/-0.002 | dg 0.553 +0.006/-0.006 | b 0.081 +0.005/-0.005 | d1 0.625 | m 0.039 +0.003/-0.000 | n min. 0.062 | FN Lbr. 700 | Fs Lbr. 1045 | g 0.025 | Fsg Lib. 610 | nabl min. 20000 | lbs 0.946 |
| Row, ring 15 | ring 68 | d2 0.619 +0.0030/-0.0030 | d3 ref. 0.784 | s 0.042 +0.002/-0.002 | dg 0.608 +0.007/-0.007 | b 0.086 +0.005/-0.005 | d1 0.688 | m 0.046 +0.003/-0.000 | n min. 0.068 | FN Lbr. 800 | Fs Lbr. 1726 | g 0.026 | Fsg Lib. 880 | nabl min. 18500 | lbs 1.320 |
| Row, ring 16 | ring 75 | d2 0.676 +0.0030/-0.0030 | d3 ref. 0.845 | s 0.042 +0.002/-0.002 | dg 0.665 +0.007/-0.007 | b 0.090 +0.005/-0.005 | d1 0.750 | m 0.046 +0.003/-0.000 | n min. 0.074 | FN Lbr. 1000 | Fs Lbr. 1878 | g 0.027 | Fsg Lib. 880 | nabl min. 17500 | lbs 1.496 |
| Row, ring 17 | ring 81 | d2 0.732 +0.0030/-0.0030 | d3 ref. 0.915 | s 0.042 +0.002/-0.002 | dg 0.721 +0.007/-0.007 | b 0.097 +0.005/-0.005 | d1 0.812 | m 0.046 +0.003/-0.000 | n min. 0.080 | FN Lbr. 1150 | Fs Lbr. 2040 | g 0.029 | Fsg Lib. 880 | nabl min. 16000 | lbs 1.716 |
| Materials / finish | Not printed by the collected specification — per RFQ |
| MOQ / lead time | Not owner-confirmed for this family — confirmed at quotation |
- Unit conflict (source-level, verified against the collected page): the source header prints "All measurements in millimeters (mm)" while every value follows the imperial retaining-ring convention — the 2103–5103 series numbering, the decimal-inch value scale and the "lbs" column match the inch-series ring tables elsewhere in the same source programme. All figures are reproduced exactly as printed with no conversion; treat the dimensional columns as inch values and confirm units at quotation.
Materials
- Not printed by the collected specification — per RFQ
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (Crescent Retaining Rings for Shafts (Series 2103–5103)) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantities and lead times for this family are confirmed at quotation — send your sizes, grades and quantities on the RFQ and the quote will carry a firm schedule. Sample availability is confirmed with the quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
When is a crescent ring the right choice over a full circlip (DIN 471)?
When the groove depth is the constraint. The crescent’s shallow section takes a much shallower groove than a DIN 471 ring of the same shaft size, which matters on hardened shafts, hollow sections, or right against a shoulder where a deep groove would weaken the part. The trade-off is a smaller retention face: crescents carry lighter axial loads than full circlips, so check the load columns against your thrust condition before committing.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support