Rocking segment and band turning two pulleys to and fro — dimension sheet
Source: Xem Studio, https://xemstudio.com/objects/segment-lever-band-pulleys-mechanism/  (sheet CC BY 4.0; files Xem Studio Design License, https://xemstudio.com/license/)
Basis: Xem Studio design following Brown No. 6 (1868)
Catalog version: 2026-10-20

Sizes: see table below
- A lever rocking on a pivot carries a circular segment; a band fixed to both ends of the segment passes round two pulleys below. Rocking the lever pulls the band one way, then the other, so both pulleys turn back and forth together, in the same direction.
- Pulley turn = segment turn × R_segment / R_pulley = 50/20 = 2.5: rocking the lever ±20° turns each Ø40 pulley ±50°. The segment's rim spans 198.83° so the band's 174.83° of wrap stays on it.
- Band 16 × 1.5, 510.14 mm; pulleys 70 mm apart, 110 mm below the pivot. Brown's No. 6.
- Parts (each has its own page): rocking-segment-lever-r50, flanged-flat-pulley-40, band-16x1-5-segment-r50-two-pulleys-40, linear-shafts-h6.
- Brown's movement No. 6 (1868) shows it; this model is a Xem Studio design following his figure, every part at true size.

parameter  value
segment radius  50 mm
pulleys  2 × Ø40 (catalog)
ratio  2.5 : 1
band  16 × 1.5, 510.14 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. 6: figure, his text and an animation — web — Publisher's page; dimensions are facts — https://507movements.com/mm_006.html

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