Constant-diameter cam between two rollers in a yoke — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/cam-between-rollers-yoke-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 117 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- The cam turns between two rollers carried on one yoke. Its pitch curve has a constant diameter (opposite radii always add to the roller spacing), so both rollers stay in contact all round and the yoke is pushed one way by one roller's side of the cam and back by the other's.
- Pitch curve r = 22 + 6 sin θ − sin 3θ, rollers Ø10 (623 bearings on Ø3 pins) 44 mm apart: stroke 14 mm per turn. Drawn at 35°: yoke -2.48 mm from centre, both rollers touching.
- Brown's No. 117 (a cam between two rollers in a yoke working a slide-valve rod).
- Parts (each has its own page): constant-diameter-cam-c22-a6-b1-bore8, two-roller-cam-yoke-44-rods-8, ball-bearings-metric, dowel-pins-metric, linear-shafts-h6.
- Brown's movement No. 117 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
pitch curve  22 + 6 sin θ − sin 3θ
roller spacing  44 mm
stroke  14 mm
rollers  623 bearings

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. 117: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_117.html

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