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Pinion between two racks (opposite motion, pump drive)

How does one pinion move two racks in opposite directions? · Hardware · basis: Xem Studio design following Brown No. 127 (1868)

Also called: double rack and pinion, opposed racks, rack pump drive, piñón entre dos cremalleras, Ritzel zwischen zwei Zahnstangen

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

sizes
4 in table

Notes

  • A pinion between two parallel racks drives them in opposite directions at the same speed: rocking the lever on the pinion's shaft raises one rack (and its pump piston) while lowering the other.
  • Racks are two full-depth module 1, 120 mm racks with their pitch lines 20 mm apart (one pitch diameter of the 20-tooth pinion); each moves π·m·N = 62.83 mm per pinion turn.
  • Brown's No. 127 (air pump: lever and spur gear driving two racks on the piston rods).
  • Parts (each has its own page): gear-rack-m1-120-full-depth, spur-gears-module-1, hand-lever-60-bore6, dowel-pins-metric.
  • Brown's movement No. 127 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Pinion between two racks size chart

parametervalue
pinion20 T, module 1
racks2 × 120 mm, pitch lines 20 mm apart
travel62.83 mm per turn, opposite ways
lever60 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. 127: 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

opposed-racks-and-pinion-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=opposed-racks-and-pinion-mechanism

Pinion between two racks (opposite motion, pump drive), isometric render of a generated part
Render of opposed-racks-and-pinion-mechanism-assembly from the free STEP; not to scale.

Fits with

Gear rack, module 1, 120 mm, full-depth 20° teeth, isometric render of a generated part
Gear rack, module 1, 120 mm, full-depth 20° teeth120.0×11.0×8.0 mm★ 1 file
Spur gears, module 1: 10 to 80 teeth (20° involute), isometric render of a generated part
Spur gears, module 1: 10 to 80 teeth (20° involute)26 sizes★ 26 files
Hand lever, 60 mm, Ø6 hub bore, isometric render of a generated part
Hand lever, 60 mm, Ø6 hub bore74.0×18.0×5.0 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 one pinion move two racks in opposite directions?

A pinion between two parallel racks drives them in opposite directions at the same speed: rocking the lever on the pinion's shaft raises one rack (and its pump piston) while lowering the other.