V-groove pulleys and round band, 1 : 1 — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/v-groove-pulleys-round-band-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 258 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- The band wedges between the two 40° flanks: the radial belt pull is multiplied by 1/sin 20° = 2.92 as normal force on the flanks, so it grips about three times as hard as on a flat face for the same tension.
- Two equal pulleys 100 mm apart on Ø8 shafts and a Ø5 endless band, drawn seated in both grooves (band centre radius 19.31 mm).
- Brown's No. 258.
- Parts (each has its own page): v-groove-pulley-45-40deg-band5-bore8, round-band-5-c100-pulleys-45v, linear-shafts-h6.
- Brown's movement No. 258 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
pulleys  2 × Ø45 × 10
band  Ø5 round
centre distance  100 mm
ratio  1 : 1

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. 258: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_258.html

Free files (Xem Studio Design License, Xem Studio; STEP + STL, 1 parts): https://xemstudio.com/files/hardware/v-groove-pulleys-round-band-mechanism/index.json
API: https://xemstudio.com/api/geometry?object=v-groove-pulleys-round-band-mechanism