Planet-gear crank on a carrier round a fixed sun (variable traverse) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/planetary-crank-variable-traverse-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 142 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- A 30-tooth sun gear is fixed; a carrier disc turns about it carrying a 30-tooth planet that rolls round the sun, making two turns per carrier turn. A crank pin on the planet (10 mm out) therefore traces a curve whose distance from the centre swings between 20 and 40 mm, and the rod from the pin to the slider gives a traverse that lengthens and shortens from stroke to stroke: Brown's variable-traverse motion for winding and tool feeds.
- Drawn at carrier angle 50° (planet turned 274°): pin at (20.5, 13.06), slider at x = 119.65 on the catalog slot guide, rod 100 mm.
- Brown's No. 142; module 1 throughout, centre distance 30 mm, the catalog 30 T crank gear and the catalog 30 T gear (sun) on a Ø10 shaft.
- Parts (each has its own page): spur-gears-module-1, crank-gear-m1-30t-pin-r10, planet-crank-carrier-disc-52-r30-boss10, four-bar-links, slide-block-12x6, slot-guide-plate-90, linear-shafts-h6, dowel-pins-metric.
- Brown's movement No. 142 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
sun / planet  30 T / 30 T, module 1
carrier radius  30 mm
crank pin  10 mm on the planet
effective crank  20 – 40 mm
rod  100 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. 142: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_142.html

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/planetary-crank-variable-traverse-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=planetary-crank-variable-traverse-mechanism