# Tri-clamp bearing cap: 2 in cap with a long Ø3 shaft bore and two 623 seats

> How do I bring a crankshaft out of a sealed tri-clamp crankcase?

- Category: Hardware › Stirling & thermoacoustic
- Kind: Hardware
- Basis: ISO 2852 clamp face and 20° back exactly as the flat end cap on this site (gen_hardware.tc_cap); 623 bearing 3 × 10 × 4 (ISO 15); bore length and spigot are design values
- Page: https://xemstudio.com/objects/tri-clamp-bearing-cap/ · JSON: https://xemstudio.com/api/geometry?object=tri-clamp-bearing-cap · Plain text: https://xemstudio.com/objects/tri-clamp-bearing-cap/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

**Exact dimensions.** Every file is drawn at true size with no printing tolerance. The holes and pins that meet another part are listed below under Mating features, with the fit each joint needs; open those by your printer's or process's clearance before making the part.

## Notes

- A cap for a 2 in ferrule face that lets a thin crankshaft out of a crankcase that holds working gas. The face, the 1.6 mm recess and the 20° back cone are the flat end cap's, so the standard clamp and Type B gasket close it like any cap.
- On the gas side a Ø16 spigot runs 77.1 mm in from the face: through the gasket lip and through the Ø16 bore of the branch plug to the crank chamber. A 623 seat (Ø10 × 4) at the spigot end carries the shaft next to the crank; a second 623 seat in the back carries it next to the flywheel.
- Between the two seats the shaft runs in a Ø3 bore 75.1 mm long. That close running fit is the only way out for the gas: no seal, no O-ring, so almost no friction.
- Fits: Ø3 bore run on the Ø3 shaft; seats press on the 623 outer ring; spigot slide in the plug bore; the face is a clamp face.

## 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 |
|---|---|---|---|---|
| cap face | ISO 2852 (land Ø56.5–Ø64, rim 2.85, 1.6 recess, 20° back to the flat back) | standard clamp + Type B gasket | clamp | bearing-cap-* |
| shaft bore | Ø3 × 75.1 between the seats | Ø3 crankshaft (shaft-3x100): the clearance seal, the only leak path | run | bearing-cap-* |
| bearing seats | 2 × Ø10 × 4 (back and spigot end) | 623 outer ring | press | bearing-cap-* |
| spigot | Ø16 × 77.1 from the face | Ø16 bore of branch-plug-2in-bore16 | slide | bearing-cap-* |

## Sizes

| feature | value |
|---|---|
| face | ISO 2852, 2 in (Ø64 flange) |
| flat back | Ø46.7 at 6 |
| spigot | Ø16 × 77.1 from the face |
| bearing seats | 2 × Ø10 × 4 (623) |
| shaft bore | Ø3 × 75.1 (run) |

## Where the files are

- ISO (via iTeh sample): [ISO 2852 clamp liners: face profile and flange / groove diameters](https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf) — PDF — standard excerpt; dimensions are facts
- ASME: [BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)](https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment) — standard — ASME; dimensions are facts (verify at link)
- Long Earth Society: [Engine builds](https://longearthsociety.com/engineering/) — web, video — LES site

## Free STEP/STL (1 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/tri-clamp-bearing-cap/index.json

- bearing-cap-2in-b3: [STEP](https://xemstudio.com/files/hardware/tri-clamp-bearing-cap/bearing-cap-2in-b3.step) · [STL](https://xemstudio.com/files/hardware/tri-clamp-bearing-cap/bearing-cap-2in-b3.stl) — 2 in bearing cap: ISO 2852 face (land Ø56.5–Ø64, rim 2.85, recess 1.6 inside Ø56.5), 20° back to the 6 mm flat back (Ø46.7) as the flat end cap; Ø16 spigot 77.1 from the face; 623 seats Ø10 × 4 in the back and at the spigot end; Ø3 bore 75.1 long between them

## Questions

**How does the shaft get out without a seal?**

Through a Ø3 bore 75.1 mm long between two 623 seats: a long close running fit leaks very little and adds almost no friction.

**Does it fit a standard clamp and gasket?**

Yes: the face and back are the flat end cap's ISO 2852 profile.

## Fits with

- [Tri-clamp end cap, 6 mm flat: 1.5 and 2 in](https://xemstudio.com/objects/tri-clamp-end-cap/)
- [Branch plugs for a 2 in tri-clamp cross crankcase](https://xemstudio.com/objects/tri-clamp-cross-branch-plug/)
- [Inner crank webs for the tri-clamp cross gamma: two throws 90° apart on a Ø3 shaft](https://xemstudio.com/objects/tri-clamp-cross-crank-webs/)
- [Ball bearings, 683 to 6210 and flanged F6xx (ISO 15)](https://xemstudio.com/objects/ball-bearings-metric/)
- [Metric shafts Ø3 to Ø10 with D-flats and clip grooves](https://xemstudio.com/objects/metric-shafts/)
- [Build list: Tri-clamp cross diaphragm gamma, 2 in](https://xemstudio.com/objects/list-tri-clamp-cross-diaphragm-gamma/)