# QD bushings SH, SDS, SD: length, bolt circle, flange diameter and cap screws

> What are the dimensions of a QD bushing (SH, SDS, SD): length, bolt circle, flange diameter and cap screw size?

- Category: Hardware › Bearings, rails & motion
- Kind: Standard part
- Basis: Martin Sprocket catalog E-1 table (length, bolt circle, cap screws) confirmed per size by product pages for SH, SDS and SD; partial by design
- Page: https://xemstudio.com/objects/qd-bushings-sh-sds-sd/ · JSON: https://xemstudio.com/api/geometry?object=qd-bushings-sh-sds-sd · Plain text: https://xemstudio.com/objects/qd-bushings-sh-sds-sd/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** Every file is drawn at true size with no tolerance added. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your process's clearance before making the part.

## Notes

- QD (quick-disconnect) is a split tapered bushing with a flange, held by three or four cap screws on a bolt circle (Martin's table). The bushing letters give the size (JA, SH, SDS, SD, SK, SF, E, F, J, M, N, P, W, S); the hub or sheave must be 'QD' for that bushing, and the bore is chosen per shaft.
- Only the three smallest are tabulated, because they are the rows that two sources confirm: Martin's catalog E-1 (page B-4) gives length L and bolt circle; product pages for SH 3/4, SDS 1-5/8 and SD 1-3/16 confirm the bolt circles (2.25, 2.688, 2.687 / 2.688 in), the flange diameters (2.688, 3.188, 3.188 in) and, for SDS (1.375, length through bore) and SD (1.813), the length. SH: Martin L 1.250 against a retailer's overall length of 1-7/32 (1.219): a different length measure; Martin's value is shown.
- SDS cap screw: Martin lists 1/4 × 1-3/8 and one product page lists 1/4 × 1-7/8; both are shown (the SD is 1-7/8). Barrel diameter varies with the bore chosen (for example SD 2.187 in on the 1-3/16 bore, SH 1.871 in on the 3/4 bore) so it is not tabulated.
- Left out: JA, SK, SF, E, F, J, M, N, P, W and S. The Martin table text was read, but the SK length (1.125 in) is inconsistent with the other rows, SF's retailer length (2-1/16 in) differs from Martin's 2.000 in, and W / S screw entries are garbled, so those rows are not published here. Bore ranges and keyseat sizes per bushing were also not read legibly. Use Martin's, Dodge's or TB Wood's current catalogue for those sizes.
- No files: the bushing's taper, flange and barrel profile are not in the tables read, so a bushing file would be invented. For hub design use the maker's CAD (links below).

## Mating features (exact size; open press / slide / run / socket by your process clearance, leave designed and clamp as drawn)

| feature | exact | mates with | fit | files |
|---|---|---|---|---|
| bolt circle | SH 2.250 in; SDS and SD 2.688 in | QD hub bolt circle of the same bushing letter (three cap screws) | designed | all |
| cap screws | 3 × 1/4-20 × 1-3/8 (SH), 1/4-20 × 1-7/8 (SD) | hub tapped holes 1/4-20 (socket-head-cap-screws-inch) | designed | all |

## Sizes

| bushing | length L, in (mm) | bolt circle, in (mm) | cap screws (qty × size) | flange Ø, in (mm) |
|---|---|---|---|---|
| SH | 1.250 (31.8) | 2.250 (57.1) | 3 × 1/4-20 × 1-3/8 | 2.688 (68.3) |
| SDS | 1.375 (34.9) | 2.688 (68.3) | 3 × 1/4-20 × 1-3/8 (product page: 1-7/8) | 3.188 (81.0) |
| SD | 1.813 (46.1) | 2.688 (68.3) | 3 × 1/4-20 × 1-7/8 | 3.188 (81.0) |

## Where the files are

- Martin Sprocket: [Catalog E-1: QD bushings (page B-4): length L, bolt circle, cap screws for JA to S](https://dcngli4g50fhp.cloudfront.net/userfiles/ad/martinsprocket/documents/martin_e_1_catalog.pdf) — web — Publisher's page; dimensions are facts
- Applied Industrial: [Martin SH 3/4 QD bushing: barrel 1.871, flange 2.688, bolt circle 2.25, 3 × 1/4-20 × 1-3/8](https://www.applied.com/c-brands/c-martin/sh-3-4/SH-Series-QD-Bushing-0-75-in-Bore/p/100001000) — web — Publisher's page; dimensions are facts
- Applied Industrial: [Martin SDS 1-5/8 QD bushing: flange 3.188, bolt circle 2.688, length through bore 1.375, 3 × 1/4 × 1-7/8](https://www.applied.com/c-martin-sds-1-5-8/p/100000978) — web — Publisher's page; dimensions are facts
- Source Atlantic: [Martin SD 1-3/16 QD bushing: barrel 2.187, flange 3.188, length 1.813, bolt circle 2.687, 1/4-20 × 1-7/8](https://www.sourceatlantic.ca/Product/SD-1-3-16) — web — Publisher's page; dimensions are facts
- Martin Sprocket: [Martin Sprocket & Gear CAD library (sprockets, QD and taper bushings)](https://www.martinsprocket.com/) — web — Publisher's page; dimensions are facts

## Questions

**What bolt circle does an SD QD bushing have?**

2.688 in (68.3 mm): the same as the SDS; the flange diameter is 3.188 in and the length 1.813 in (SD) or 1.375 in (SDS).

**What cap screws does an SH QD bushing use?**

Three 1/4-20 × 1-3/8 in on a 2.250 in (57.2 mm) bolt circle; flange diameter 2.688 in.

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