Narrow V-belts 3V, 5V, 8V and SPZ, SPA, SPB, SPC (wedge belts): top width, height, datum width and length designation — dimension sheet Source: Xem Studio, https://xemstudio.com/objects/v-belts-narrow-3v-5v-8v-spz-spa-spb-spc/ (sheet CC BY 4.0) Basis: Optibelt (ISO 4184 / ISO 4183 narrow sections), Gates, Dayco, VBeltSupply, Tameson and GPR Industrial; sources disagree by up to 1 mm and all are shown; numbers only Catalog version: 2026-10-20 Sizes: see table below - Narrow (wedge) V-belts carry more power in less width than classical belts. Metric sections SPZ, SPA, SPB, SPC (ISO 4184 narrow) are designated by the datum length Ld in mm; the US sections 3V, 5V, 8V (RMA IP-20; 9N, 15N, 25N in Optibelt's naming) are designated by outside length in tenths of an inch (3V250 is 25.0 in). SPZ and 3V, SPB and 5V are close in size but are different belts and different grooves: they are not interchangeable. - Where the sources disagree (they do, by up to 1 mm in top width): Optibelt's table, which follows ISO 4184, prints SPZ 9.7, SPA 12.7, SPB 16.3 and SPC 22 mm wide; Gates' catalogue, VBeltSupply and GPR Industrial print the rounded 10, 13, 17, 22 mm; Tameson prints 9.7 / 12.7 / 17 / 22. For 3V / 5V / 8V: Optibelt 9 / 15 / 25 × 8 / 13 / 23, Gates 10 / 17 / 26 × 8 / 13 / 23 (printed as SPZ-3V, SPB-5V, 8V), Dayco 3V 9.5 × 8, VBeltSupply 3/8 / 5/8 / 1 in wide and 21/64 / 35/64 / 7/8 in high, Tameson 9.7 / 15.8 / 25.4 × 8 / 14 / 23. Heights agree within 1 mm. All the numbers are shown; none is chosen as 'the' size. - Datum width (wd) is the groove width at the datum line from ISO 4183, as used on the pulley-groove page (SPZ 8.5, SPA 11, SPB 14, SPC 19 mm); 3V, 5V and 8V sheaves follow RMA / MPTA groove tables, which are not tabulated here. Aims Industrial prints inside-to-pitch length additions for the narrow metric sections: SPZ 13 mm, SPA 18 mm, SPB 22 mm, SPC 30 mm (single source; use your maker's table). Gates' Powerband catalogue prints 3V / 5V / 8V rib pitches of 10.30, 17.50 and 28.60 mm and SPB / SPC 19.00 and 25.50 mm for banded belts. - Groove / belt angle: Aims Industrial states a 40° belt angle for A and SPZ; a US belt retailer describes SP belts with a 38° wedge angle (that is the ISO 4183 pulley-groove angle for larger diameters, not the belt angle). No angle is tabulated here for that reason. - Not on this page: banded (Powerband) widths, cogged raw-edge (XPZ, XPA, XPB, 3VX, 5VX) variations, tolerances and matching, belt length tables, minimum sheave diameters. McMaster-Carr's V-belt category is linked below for per-belt CAD. section Optibelt / ISO, top width × height, mm Gates, mm Dayco / VBeltSupply inch (mm in brackets) Tameson, mm datum width wd, mm (ISO 4183) length designation SPZ 9.7 × 8 10 × 8 (listed with 3V) 10 × 8 mm (VBeltSupply) 9.7 × 8 8.5 datum length Ld, mm (e.g. SPZ 767) SPA 12.7 × 10 13 × 10 13 × 10 mm (Dayco, VBeltSupply) 12.7 × 10 11 datum length Ld, mm SPB 16.3 × 13 17 × 13 (listed with 5V) 17 × 13 mm (VBeltSupply) 17 × 13 14 datum length Ld, mm SPC 22 × 18 22 × 18 22 × 18 mm (VBeltSupply) 22 × 18 19 datum length Ld, mm 3V / 9N 9 × 8 (9N) 10 × 8 (listed with SPZ) 3/8 × 21/64 in (VBeltSupply, 9.5 × 8.3); 9.5 × 8 mm (Dayco) 9.7 × 8 — outside length in tenths of an inch (3V250 = 25.0 in; Dayco 3V250DR 25.00 in) 5V / 15N 15 × 13 (15N) 17 × 13 (listed with SPB) 5/8 × 35/64 in (VBeltSupply, 15.9 × 13.9) 15.8 × 14 — outside length in tenths of an inch (5V620 = 62.0 in, VBeltSupply) 8V / 25N 25 × 23 (25N) 26 × 23 1 × 7/8 in (VBeltSupply, 25.4 × 22.2) 25.4 × 23 — outside length in tenths of an inch Files elsewhere (not hosted by Xem Studio; license as stated by the publisher): - Optibelt: Belt range: classical V-belt table (DIN 2215 / ISO 4184 width b, height h, Li / Ld) and wedge / narrow belt tables — web — Publisher's page; dimensions are facts — https://santent.in/wp-content/uploads/2020/08/Optibelt-Belt-Range.pdf - Gates (Statewide Bearings copy): Industrial V-belt catalogue: section widths and heights, datum and outside lengths — web — Publisher's page; dimensions are facts — https://www.statewidebearings.com.au/wp-content/uploads/2018/06/Gates-Industrial-V-Belts-1.pdf - Dayco: Industrial product guide: V-belt Li and Ld examples per section, A 13 x 8, 3V 9.5 x 8, SPA 13 x 10 — web — Publisher's page; dimensions are facts — https://na.daycoaftermarket.com/wp-content/uploads/IND-DR-VB-PG-0619-Industrial-Product-Guide.pdf - VBeltSupply: Belt spec guide: inch top width x height for classical, 3V / 5V / 8V, SPZ to SPC; length designation examples — web — Publisher's page; dimensions are facts — https://www.vbeltsupply.com/media/wysiwyg/guides/belt-spec-guide.pdf - Tameson: V-belt size chart: top width and height of Z, A, B, C, D, E, 3V, 5V, 8V, SPZ, SPA, SPB, SPC — web — Publisher's page; dimensions are facts — https://tameson.com/v-belt-size-chart.html - Aims Industrial: How to measure a V-belt: Li, La, Ld definitions; narrow-section inside-to-pitch length additions — web — Publisher's page; dimensions are facts — https://aimsindustrial.com.au/blogs/product-guides/blog-how-to-measure-a-v-belt - ISO: ISO 4184:2025 Belt drives, classical and narrow V-belts, lengths in datum system (standard; sold, not reproduced) — standard — ISO; dimensions are facts [verify license at link] — https://www.iso.org/standard/88704.html - McMaster-Carr: V-belts (classical, narrow, banded) (free STEP/IGES per part, for your own design use; no redistribution) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution [verify license at link] — https://www.mcmaster.com/c81-v-belts No true-size file yet: the published figures do not fix the whole shape; a measured scan is planned. API: https://xemstudio.com/api/geometry?object=v-belts-narrow-3v-5v-8v-spz-spa-spb-spc