Pinion between two racks (opposite motion, pump drive) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/opposed-racks-and-pinion-mechanism/  (CC BY 4.0)
Basis: Xem Studio design following Brown No. 127 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- 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.

parameter  value
pinion  20 T, module 1
racks  2 × 120 mm, pitch lines 20 mm apart
travel  62.83 mm per turn, opposite ways
lever  60 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. 127: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_127.html

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