{ "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": "bell-crank-lever-mechanism", "name": "Bell-crank lever turning a pull through 90°", "kind": "hardware", "category": "Mechanisms", "group": "Linkages", "year": null, "question": "What does a bell crank do?", "tags": [ "mechanism", "linkages", "kinematics", "507 mechanical movements" ], "aliases": [ "bell crank", "bell crank lever", "angle lever", "palanca acodada", "Winkelhebel" ], "overall_mm": { "length": null, "width": null, "height": null }, "official_cad": false, "xem_status": "free-files", "les": false, "free_files": 1, "url": "https://xemstudio.com/objects/bell-crank-lever-mechanism/", "sheet_txt": "https://xemstudio.com/objects/bell-crank-lever-mechanism/sheet.txt", "sheet": { "basis": "Xem Studio design following Brown No. 126 (1868)", "overall_mm": { "length": null, "width": null, "height": null }, "notes": [ "An L-shaped lever on a pivot at its corner: a pull on one arm becomes a pull at right angles on the other. Force ratio = arm lengths (1 : 1 for 30 × 30 mm; the 20 × 40 crank gives 2 : 1).", "Here the catalog 30 × 30 bell crank turns on a 623 bearing pressed in its Ø10 pocket, with 60 mm links on each arm.", "Brown's No. 126; used in bell-pulls, control rods and brakes to change the direction of a push or pull.", "Parts (each has its own page): bell-cranks, ball-bearings-metric, four-bar-links, dowel-pins-metric.", "Brown's movement No. 126 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size." ], "table": { "columns": [ "parameter", "value" ], "rows": [ [ "arms", "30 × 30 mm at 90°" ], [ "pivot", "623 bearing on Ø3 pin" ], [ "links", "2 × 60 mm" ], [ "ratio", "1 : 1" ] ] } }, "sheet_text": "Bell-crank lever turning a pull through 90° — dimension sheet\nSource: Xem Studio, https://xemstudio.com/objects/bell-crank-lever-mechanism/ (CC BY 4.0)\nBasis: Xem Studio design following Brown No. 126 (1868)\nCatalog version: 2026-10-20\n\nSizes: see table below\n- An L-shaped lever on a pivot at its corner: a pull on one arm becomes a pull at right angles on the other. Force ratio = arm lengths (1 : 1 for 30 × 30 mm; the 20 × 40 crank gives 2 : 1).\n- Here the catalog 30 × 30 bell crank turns on a 623 bearing pressed in its Ø10 pocket, with 60 mm links on each arm.\n- Brown's No. 126; used in bell-pulls, control rods and brakes to change the direction of a push or pull.\n- Parts (each has its own page): bell-cranks, ball-bearings-metric, four-bar-links, dowel-pins-metric.\n- Brown's movement No. 126 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.\n\nparameter value\narms 30 × 30 mm at 90°\npivot 623 bearing on Ø3 pin\nlinks 2 × 60 mm\nratio 1 : 1\n\nFiles elsewhere (not hosted by Xem Studio; license as stated by the publisher):\n- Henry T. Brown (1868, public domain): Five Hundred and Seven Mechanical Movements — scan on archive.org — web — Publisher's page; dimensions are facts — https://archive.org/details/fivehundredseven00browiala\n- 507movements.com: Brown's movement No. 126: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_126.html\n\nFree files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/bell-crank-lever-mechanism/index.json\nAPI: https://xemstudio.com/api/geometry?object=bell-crank-lever-mechanism\n", "sources": [ { "publisher": "Henry T. Brown (1868, public domain)", "title": "Five Hundred and Seven Mechanical Movements — scan on archive.org", "url": "https://archive.org/details/fivehundredseven00browiala", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false }, { "publisher": "507movements.com", "title": "Brown's movement No. 126: figure, his text and an animation", "url": "https://507movements.com/mm_126.html", "formats": [ "web" ], "license": "Publisher's page; dimensions are facts", "license_verified": true, "hosted": false } ], "xem": { "status": "free-files", "sheet_free": true, "mesh_price_usd": null, "step_price_usd": null, "tolerance_mm": null }, "related": [ "bell-cranks", "ball-bearings-metric", "four-bar-links", "dowel-pins-metric" ], "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": [], "faq": [ { "q": "What does a bell crank do?", "a": "An L-shaped lever on a pivot at its corner: a pull on one arm becomes a pull at right angles on the other. Force ratio = arm lengths (1 : 1 for 30 × 30 mm; the 20 × 40 crank gives 2 : 1)." } ], "files_license": null, "offers": [ { "file": "bell-crank-lever-mechanism-assembly", "formats": [ "step", "stl" ], "price_usd": 0, "license": "CC BY 4.0 (Xem Studio)", "step": "https://xemstudio.com/files/hardware/bell-crank-lever-mechanism/bell-crank-lever-mechanism-assembly.step", "stl": "https://xemstudio.com/files/hardware/bell-crank-lever-mechanism/bell-crank-lever-mechanism-assembly.stl", "note": "Assembled mechanism, all parts placed at one pose (STEP keeps each part separate)" } ], "markdown": "https://xemstudio.com/objects/bell-crank-lever-mechanism/index.md" }