How to Read V-Belt Part Numbers: A, B, BX, 5V, SPZ and SPB

A catalog-data view of V-belt part numbers: how to split section, length code and construction prefixes, why length bases differ by family, and what to map to structured attributes.

A V-belt part number usually packs a section (the profile letter or code), a length code and sometimes a construction or band-count marker into one string. What the length code measures depends on the belt family, so a parser must record the section, the length value and the length basis as separate fields before any two belts are compared.

Why V-belt part numbers are hard to parse

The V-belt attribute template already notes that section and length are built into codes such as 5VX1180, and that classical, narrow and metric belts use inside, effective or datum lengths, so the number is only comparable within its own family. Supplier files rarely state the basis. That is the core parsing problem.

A parsing model

Treat a part number as a candidate string to split, not as a decoded fact. For each string, produce:

Parsed field	What to capture	Status
Belt section	The profile letters or code, e.g. `5VX` in the template's example `5VX1180`	Structure confirmed by the Claro template; per-family meaning: Needs review
Length code	The digits after the section, kept exactly as printed	Meaning per family: Needs review
Length measurement basis	Inside, outside, effective, pitch or datum length, as a controlled value	Must come from the manufacturer catalog, never inferred from the digits
Construction marker	Letter suffixes or product-line names that indicate wrapped, raw-edge or cogged	Brand-specific: Needs review
Band count or tie	A prefix or separate field for banded belts	Brand-specific: Needs review
Brand part number	The manufacturer's own catalog number, kept separate from the industry designation	Store both

Notation conventions by family

Family	Example section codes named in the title	Length basis	Primary source to confirm
Classical	A, B, BX	Needs review	RMA/MPTA/ARPM IP-20; ISO 4184; manufacturer catalogs
Narrow (North American)	5V, 5VX	Needs review	RMA/MPTA/ARPM IP-22; manufacturer catalogs
Metric ISO profile	SPZ, SPB	Datum length is the ISO 4184 system (Needs review for exact notation)	ISO 4184; ISO 4183 / 5290 for grooves; Optibelt, Continental, Dayco catalogs

What catalog attribute mapping does with each part

1

Split

Separate section, length code and any prefix or suffix, keeping the original string.
2

Assign the basis

Take the length basis from the manufacturer’s table. If it is missing, leave it blank and flag the record.
3

Convert for comparison

Store the number and unit, then use the unit and dimension converter only for unit changes, not to translate between length bases.
4

Record the relationship

A name or size match is a candidate. Label it with a relationship type and its evidence, never as an automatic substitute.

Future work: a dedicated V-belt part number decoder could automate the split step. None exists today.

Naming match is not approval to substitute

Before treating two belts as interchangeable, check: the length type (pitch, datum, effective or outside), section or profile, construction (wrapped, raw-edge, cogged), band count and ties, matched-set requirements, sheave groove, power rating, temperature, oil and static conductivity, and brand-specific notation. The functional-equivalent playbook and the guide on matching supplier products without a GTIN cover how to hold candidates for review.

Sources

No external source has been verified yet. Primary documents to consult before publishing: Gates, Carlisle, Bando and Optibelt/Continental/Dayco V-belt catalogs; ISO 4184, ISO 1081, ISO 4183, ISO 5290; RMA/MPTA/ARPM IP-20, IP-22 and IP-3-3.

Attribute Library

V-Belt Attributes & Template

Fields to capture for each V-belt SKU.

Guide

Product Relationship Types

Labelling candidates without over-claiming.

Glossary

Data Normalization

Standardizing messy attribute values.

Playbook

Find Functional Equivalents

Attribute-based comparison workflow.

FAQ

Does the number in a V-belt part number mean the same thing in every belt family?

No. Classical, narrow and metric belts measure length on different bases, such as inside, effective or datum length, so the length code is only comparable within its own family. Store the length basis as its own field.

Is a V-belt part number enough to approve a substitute?

No. A matching section and length code is a naming correspondence, not an engineering approval. Construction, band count, matched-set rules, sheave groove, power rating and brand-specific notation still have to be checked against the manufacturer’s data.