{
 "version": "2026-10-20",
 "license": "Dimension sheets are written by Xem Studio from the cited sources and are free to use (CC BY 4.0, attribute 'Xem Studio'). Linked files belong to their publishers under the license shown; Xem Studio does not host them. 'license_verified: false' means the license shown is from memory or the publisher's page as last read and should be confirmed at the link before commercial use.",
 "slug": "tri-clamp-cross-crankcase-insert",
 "name": "Crankcase insert for a 2 in tri-clamp cross: displacer-rod guide, crank chamber and run filler",
 "kind": "hardware",
 "category": "Hardware",
 "group": "Stirling & thermoacoustic",
 "year": null,
 "question": "How do I guide a displacer rod and fill the dead volume inside a 2 inch tri-clamp cross?",
 "tags": [
  "filler",
  "guide",
  "crankcase",
  "dead volume",
  "cross",
  "tri-clamp",
  "stirling",
  "long earth society"
 ],
 "aliases": [
  "tri clamp cross insert",
  "displacer rod guide tri clamp",
  "crankcase filler stirling",
  "reduce dead volume cross"
 ],
 "overall_mm": {
  "length": null,
  "width": null,
  "height": null
 },
 "official_cad": false,
 "xem_status": "free-files",
 "les": true,
 "free_files": 1,
 "url": "https://xemstudio.com/objects/tri-clamp-cross-crankcase-insert/",
 "sheet_txt": "https://xemstudio.com/objects/tri-clamp-cross-crankcase-insert/sheet.txt",
 "sheet": {
  "basis": "ASME BPE 2 in bore Ø47.5; ISO 2852 Type B lip (Ø45.3, 2.8 from the joint plane); slot, chamber and gap sizes are design values from the crank and con-rods",
  "overall_mm": {
   "length": null,
   "width": null,
   "height": null
  },
  "notes": [
   "One piece that fills the run of a 2 in cross with the working gas still free to move. It drops in from the top, stands on the lower gasket's lip and passes the lip with a Ø45.3 spigot that ends level with the lip's lower face.",
   "Lower run: a Ø3 bore 31.55 mm long is the displacer-rod guide (running fit). Above it a column for the displacer's rod clevis and a slab for its con-rod; two Ø8 passages carry the gas from under the insert to the crank chamber; a Ø18 pocket at the bottom takes the displacer cap's boss at the top of its stroke.",
   "Middle: a Ø29 chamber straight through along the branch axis; the two branch plugs' noses fill its ends up to the crank. Upper run: slab and column for the diaphragm con-rod and clevis, a Ø22 pocket for the centre disc and nuts, and a cone that stays 1 mm under the membrane at full inward travel.",
   "Fits: Ø47.5 slide in the bore; spigot touches the lip's Ø45.3; Ø3 guide run on the rod. Chamber, slots and the gap under the membrane are designed."
  ],
  "table": {
   "columns": [
    "feature",
    "value"
   ],
   "rows": [
    [
     "outside",
     "Ø47.5, -86.95 to 88.25 from the cross centre"
    ],
    [
     "spigot",
     "Ø45.3 to -92.55"
    ],
    [
     "guide",
     "Ø3 × 31.55"
    ],
    [
     "crank chamber",
     "Ø29 along X"
    ],
    [
     "gas passages",
     "2 × Ø8"
    ],
    [
     "gap under the membrane",
     "1 at ±6 travel"
    ]
   ]
  }
 },
 "sheet_text": "Crankcase insert for a 2 in tri-clamp cross: displacer-rod guide, crank chamber and run filler — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/tri-clamp-cross-crankcase-insert/  (CC BY 4.0)\nBasis: ASME BPE 2 in bore Ø47.5; ISO 2852 Type B lip (Ø45.3, 2.8 from the joint plane); slot, chamber and gap sizes are design values from the crank and con-rods\nCatalog version: 2026-10-20\n\nSizes: see table below\n- One piece that fills the run of a 2 in cross with the working gas still free to move. It drops in from the top, stands on the lower gasket's lip and passes the lip with a Ø45.3 spigot that ends level with the lip's lower face.\n- Lower run: a Ø3 bore 31.55 mm long is the displacer-rod guide (running fit). Above it a column for the displacer's rod clevis and a slab for its con-rod; two Ø8 passages carry the gas from under the insert to the crank chamber; a Ø18 pocket at the bottom takes the displacer cap's boss at the top of its stroke.\n- Middle: a Ø29 chamber straight through along the branch axis; the two branch plugs' noses fill its ends up to the crank. Upper run: slab and column for the diaphragm con-rod and clevis, a Ø22 pocket for the centre disc and nuts, and a cone that stays 1 mm under the membrane at full inward travel.\n- Fits: Ø47.5 slide in the bore; spigot touches the lip's Ø45.3; Ø3 guide run on the rod. Chamber, slots and the gap under the membrane are designed.\n\nfeature  value\noutside  Ø47.5, -86.95 to 88.25 from the cross centre\nspigot  Ø45.3 to -92.55\nguide  Ø3 × 31.55\ncrank chamber  Ø29 along X\ngas passages  2 × Ø8\ngap under the membrane  1 at ±6 travel\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- ISO (via iTeh sample): ISO 2852 clamp liners: face profile and flange / groove diameters — PDF — standard excerpt; dimensions are facts — https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf\n- ASME: BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall) — standard — ASME; dimensions are facts [verify license at link] — https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment\n- Long Earth Society: Engine builds — web, video — LES site — https://longearthsociety.com/engineering/\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/tri-clamp-cross-crankcase-insert/index.json\nAPI: https://xemstudio.com/api/geometry?object=tri-clamp-cross-crankcase-insert\n",
 "sources": [
  {
   "publisher": "ISO (via iTeh sample)",
   "title": "ISO 2852 clamp liners: face profile and flange / groove diameters",
   "url": "https://cdn.standards.iteh.ai/samples/7850/eb49c396488d408c8ced3e2961d76cf3/ISO-2852-1974.pdf",
   "formats": [
    "PDF"
   ],
   "license": "standard excerpt; dimensions are facts",
   "license_verified": true,
   "hosted": false
  },
  {
   "publisher": "ASME",
   "title": "BPE Bioprocessing Equipment (clamp fitting dimensions, tube OD and wall)",
   "url": "https://www.asme.org/codes-standards/find-codes-standards/bpe-bioprocessing-equipment",
   "formats": [
    "standard"
   ],
   "license": "ASME; dimensions are facts",
   "license_verified": false,
   "hosted": false
  },
  {
   "publisher": "Long Earth Society",
   "title": "Engine builds",
   "url": "https://longearthsociety.com/engineering/",
   "formats": [
    "web",
    "video"
   ],
   "license": "LES site",
   "license_verified": true,
   "hosted": false
  }
 ],
 "xem": {
  "status": "free-files",
  "sheet_free": true,
  "mesh_price_usd": null,
  "step_price_usd": null,
  "tolerance_mm": null
 },
 "related": [
  "tri-clamp-cross-branch-plug",
  "tri-clamp-cross-crank-webs",
  "sanitary-clamp-crosses",
  "tri-clamp-volume-filler",
  "list-tri-clamp-cross-diaphragm-gamma"
 ],
 "fits": [],
 "dimensions": "exact (nominal, no printing tolerance)",
 "dimension_rule": "All geometry on Xem Studio is exact (nominal, true size) with no printing tolerance. Where a part meets another part, the object lists its mating features (feature, exact size, what it mates with, fit class: press, slide, run, socket, clamp or designed). Apply your process's allowance to those features only; 'designed' gaps are part of the design and stay as drawn.",
 "mating": [
  {
   "feature": "outside",
   "exact": "Ø47.5",
   "mates": "2 in cross run bore",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "spigot",
   "exact": "Ø45.3",
   "mates": "Type B gasket lip (ID 45.3)",
   "fit": "slide",
   "files": "all"
  },
  {
   "feature": "displacer-rod guide",
   "exact": "Ø3 × 31.55",
   "mates": "Ø3 displacer rod (crankshaft-3x60): runs in it",
   "fit": "run",
   "files": "all"
  },
  {
   "feature": "crank chamber",
   "exact": "Ø29 along the branch axis",
   "mates": "branch-plug noses; crank sweep R 13",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "con-rod slabs and clevis columns",
   "exact": "7 × 18 and 9 × 18 slabs, 13 × 11 boxes, Ø12 round columns",
   "mates": "con-rods and rod clevises in motion",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "membrane cone",
   "exact": "1.0 under the membrane at ±6 travel; Ø22 disc pocket",
   "mates": "centre disc, nuts and boss at full inward travel",
   "fit": "designed",
   "files": "all"
  },
  {
   "feature": "gas passages",
   "exact": "2 × Ø8",
   "mates": "gas path from the displacer to the crank chamber",
   "fit": "designed",
   "files": "all"
  }
 ],
 "fit_classes": {
  "press": "stays put: pin, tube, bearing or magnet held by interference. Typical FDM: hole +0.0 to +0.1 mm on diameter.",
  "slide": "assembles by hand and is held by a grub, pinch or clamp: shaft in a hub, rod in a socket, spigot in a bore. Typical FDM: +0.2 mm.",
  "run": "turns or slides in use: pin in a link, rod through a guide. Typical FDM: +0.3 mm.",
  "socket": "large sliding fit: syringe barrel, sleeve, bobbin in a bore. Typical FDM: +0.3 mm.",
  "clamp": "split part that closes on the mating part with screws: make it at size.",
  "designed": "a gap that is part of the design (piston fit option, displacer gap, air gap): do not change."
 },
 "faq": [
  {
   "q": "Why fill the cross?",
   "a": "The open 2 in cross holds about 0.55 L of gas; the engine sweeps about 11 mL. Every bit of unswept gas lowers the pressure swing."
  },
  {
   "q": "Where does the gas go?",
   "a": "Up past the displacer, through the two Ø8 passages and the slots into the crank chamber, and up the diaphragm slot to the membrane."
  }
 ],
 "files_license": null,
 "offers": [
  {
   "file": "crankcase-insert-2in",
   "formats": [
    "step",
    "stl"
   ],
   "price_usd": 0,
   "license": "CC BY 4.0 (Xem Studio)",
   "step": "https://xemstudio.com/files/hardware/tri-clamp-cross-crankcase-insert/crankcase-insert-2in.step",
   "stl": "https://xemstudio.com/files/hardware/tri-clamp-cross-crankcase-insert/crankcase-insert-2in.stl",
   "note": "2 in cross crankcase insert: Ø47.5 from the lower lip (-86.95) to the rim (88.25), Ø45.3 spigot to -92.55 (from the cross centre); Ø29 crank chamber along the branches; Ø3 guide 31.55 long; two Ø8 gas passages; membrane cone 1 under full inward travel"
  }
 ],
 "markdown": "https://xemstudio.com/objects/tri-clamp-cross-crankcase-insert/index.md"
}