Plate cam with roller follower (cycloidal rise) — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/plate-cam-roller-follower-mechanism/  (CC BY 4.0)
Basis: Xem Studio design following Brown No. 138 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- A disc cam turning on its shaft lifts a roller follower that slides in a straight guide: the profile is drawn from the displacement law — here cycloidal rise of 12 mm over 120°, dwell, return, dwell.
- Roller: rolling contact, low wear; the cam is the pitch curve offset by the roller radius (5 mm). Cycloidal motion has zero acceleration at both ends of the rise.
- Drawn at 60° of cam rotation (mid-rise, lift 6 mm) with the follower touching the profile; follower guide 30 × 16 block. Brown's No. 138.
- Parts (each has its own page): plate-cam-cycloidal-roller-r20-h12, roller-follower-fork-rod-8, roller-follower-10, follower-guide-block-8.
- Brown's movement No. 138 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
base circle  R20
rise  12 mm / 120°
law  cycloidal
follower  roller
pose  60°, lift 6 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. 138: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_138.html

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