English to Bulgarian Tech/Engineering Mechanics / Mech Engineering

Datum length ISO.
Брошура на клиновидни ремъци (wedge belts) на фирмата Optibelt.
....
The term "Datum" was first adopted by the International Standards Organization (ISO 1081-1980) and most
recently by the Rubber Manufacturers Association Engineering Standard for Classical V-Belts and Sheaves (IP-
20-1988. This datum system defines specific sheave and belt dimensions previously known as the pitch system
for classical belts and sheaves. What were previously identified as pitch diameter or pitch length are now
known as datum diameter or datum length. These are the new catalog identifiers which allow all belt and
sheave manufacturers and users to use the same nomenclature. ... (http://www.gates.com/facts/documents/Gf000209.pdf)

В български каталози намерих единствено "дължина" и "ширина".