Xem Studiomeasured geometry

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Double-sided rack between two equal gears

Why drive a rack from both sides? · Hardware · basis: Xem Studio design following Brown No. 115 (1868)

Also called: double rack and pinions, rack between two gears, two gear rack drive, cremallera entre dos engranajes, Zahnstange zwischen zwei Rädern

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

sizes
4 in table

Notes

  • Two equal gears on fixed shafts 32 mm apart, turning in opposite directions, mesh with the two toothed edges of one rack: the rack is pushed with equal force and speed on both edges, so it runs straight with no side load on its guides.
  • Module 1, 20-tooth gears (pitch Ø20) with their axes 10 mm outside each pitch line; one turn moves the rack 62.83 mm. Drawn with the rack one pitch (π mm) along.
  • Brown's No. 115 (two equal toothed wheels driving a double rack).
  • Parts (each has its own page): double-sided-rack-m1-100-pitch-12, spur-gears-module-1, dowel-pins-metric.
  • Brown's movement No. 115 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

Double-sided rack between two equal gears size chart

parametervalue
gears2 × 20 T, module 1
shaft centres32 mm
rack100 mm, teeth both sides
travel per turn62.83 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. 115: figure, his text and an animationwebPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

double-rack-two-gears-mechanism-assemblyAssembled mechanism, all parts placed at one pose (STEP keeps each part separate)STEP · STL
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Plain text: sheet.txt · JSON: /api/geometry?object=double-rack-two-gears-mechanism

Double-sided rack between two equal gears, isometric render of a generated part
Render of double-rack-two-gears-mechanism-assembly from the free STEP; not to scale.

Fits with

Double-sided gear rack, module 1, 100 mm, pitch lines 12 mm apart, isometric render of a generated part
Double-sided gear rack, module 1, 100 mm, pitch lines 12 mm apart100.0×14.0×8.0 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
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

Why drive a rack from both sides?

Two equal gears on fixed shafts 32 mm apart, turning in opposite directions, mesh with the two toothed edges of one rack: the rack is pushed with equal force and speed on both edges, so it runs straight with no side load on its guides.