Rack and pinion, module 1 (20 T pinion, 120 mm rack) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/rack-and-pinion-mechanism/  (CC BY 4.0)
Basis: Xem Studio design following Brown No. 113 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- A pinion turning on a fixed axis drives a straight toothed rack: one turn moves the rack π·m·N = 62.83 mm for a 20-tooth module 1 pinion (its pitch circumference). Either part can drive.
- The rack is the basic rack of the involute system (straight 20° flanks), so it meshes with every module 1 gear; the pinion's axis sits exactly one pitch radius (10 mm) above the rack's pitch line.
- Brown's No. 113: circular motion to straight-line motion and back.
- Parts (each has its own page): spur-gears-module-1, gear-rack-m1-120-full-depth.
- Brown's movement No. 113 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
module  1
pinion  20 T, pitch Ø20
rack  120 mm
travel per turn  62.83 mm
pinion axis above pitch line  10 mm

Files elsewhere (not hosted by Xem Studio; license as stated by the publisher):
- 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
- 507movements.com: Brown's movement No. 113: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_113.html

Free files (CC BY 4.0, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/rack-and-pinion-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=rack-and-pinion-mechanism