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Ratchet wheel stepped by a swinging pawl lever

How does a pawl lever step a ratchet wheel? · Hardware · basis: Xem Studio design following Brown No. 225 (1868)

Also called: ratchet feed, ratchet lever, intermittent ratchet, pawl and ratchet mechanism, trinquete con palanca de avance, Schaltwerk mit Klinkenhebel

Exact dimensions. True size, with no printing tolerance added.

sizes
3 in table

Notes

  • A lever swinging on the wheel's shaft carries a pawl: on the working stroke the pawl pushes a tooth's steep face and turns the wheel; on the return it rides back over the sloping backs. Rocking becomes step-by-step rotation, one or more teeth (15° each for 24 teeth) per stroke.
  • Catalog 24-tooth Ø40 ratchet wheel with a feed pawl on a 30 mm arm; drawn at the start of a working stroke with the pawl's end face flat on the tooth's steep face (contact only).
  • Brown's No. 225 (pawl on a vibrating arm turning a ratchet wheel intermittently). A light spring keeps the pawl down (not drawn).
  • Parts (each has its own page): ratchet-wheels, ratchet-feed-pawl-24t-d40, ratchet-feed-arm-30, dowel-pins-metric.
  • Brown's movement No. 225 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Ratchet wheel stepped by a swinging pawl lever size chart

parametervalue
wheel24 T, Ø40 (catalog)
step15° per tooth
pawl pivot radius30 mm

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

Henry T. Brown (1868, public domain)Five Hundred and Seven Mechanical Movements — scan on archive.orgwebPublisher's page; dimensions are facts
507movements.comBrown's movement No. 225: figure, his text and an animationwebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Generated by Xem Studio from the standard; threads are plain cylinders at major diameter. CC BY 4.0. index.json

ratchet-feed-lever-mechanism-assemblyAssembled mechanism, all parts placed at one pose (STEP keeps each part separate)STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
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Plain text: sheet.txt · JSON: /api/geometry?object=ratchet-feed-lever-mechanism

Ratchet wheel stepped by a swinging pawl lever, isometric render of a generated part
Render of ratchet-feed-lever-mechanism-assembly from the free STEP; not to scale.

Fits with

Ratchet wheels Ø40 with 12, 24 and 36 teeth, isometric render of a generated part
Ratchet wheels Ø40 with 12, 24 and 36 teeth3 sizes★ 3 files
Feed pawl for the 24-tooth Ø40 ratchet (pivot 30 mm from the wheel axis), isometric render of a generated part
Feed pawl for the 24-tooth Ø40 ratchet (pivot 30 mm from the wheel axis)18.39×8.0×6.0 mm★ 1 file
Ratchet feed arm, pawl pivot at 30 mm, Ø5 hub, isometric render of a generated part
Ratchet feed arm, pawl pivot at 30 mm, Ø5 hub77.0×14.0×5.0 mm★ 1 file
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325), isometric render of a generated part
Dowel pins, 2–6 mm (ISO 2338 / DIN 6325)5 sizes★ 23 files

Questions

How does a pawl lever step a ratchet wheel?

A lever swinging on the wheel's shaft carries a pawl: on the working stroke the pawl pushes a tooth's steep face and turns the wheel; on the return it rides back over the sloping backs. Rocking becomes step-by-step rotation, one or more teeth (15° each for 24 teeth) per stroke.