ISO 9981-2020-06 pdf free.Belt drives —Pulleys and V-ribbedbelts for the automotive industry — PK profile: Dimensions.
This document specifies the principal dimensional characteristics of V-ribbed pulley groove profiles,together with the corresponding endless V-ribbed belts of PK profile which are used predominantly forautomotive accessory drive applications.
This document does not apply to the complete array of V-ribbed belts and pulleys of PH,P),PK, PL andPM profile for industrial and other non-automotive applications which are covered by ISO 9982.PK beltprofile dimensions and tolerances are the same in both International Standards.
6.2 and 6.3 of this document do not apply to elastic belts.There are no normative references in this document.No terms and definitions are listed in this document.Groove-to-groove diameter tolerances:The variation in diameters between the grooves in any one pulley shall not exceed 0,15 mm.Thisvariation is obtained by comparing the diameters over balls or rods.
Radial and axial circular run-out:Radial and axial circular run-outs shall not exceed 0,25 mm full indicator movement(FIM).Run-out inthe two directions is measured separately with a ball mounted under spring pressure to ensure contactwith the groove as the pulley is rotated.
Diameter over balls:The tolerances on the diameters over balls, K, shall not exceed ±0,6 mm.5.3.5 Groove finish
The pulley grooves shall have a surface roughness Ra ≤ 3,2 um.See IS0 254and IS0 4287 for definitionsand the method of measurement.
Pitch diameter, dp:The fit of a V-ribbed belt in the corresponding pulley is shown in Figure 3.The true pitch diameter of aV-ribbed pulley is slightly larger than the effective diameter and its exact value is determined with theparticular belt being used.
A nominal value of the effective line differential, bl, of 2 mm may be used to calculate the speed ratio. lfmore precision is required, the belt manufacturer should be consulted.
A V-ribbed pulley for the automotive industry is characterized by the number of grooves, the profileand the effective diameter. lt is designated by a series of numbers and letters as follows:
a) the first letter “P” means “Pulley”;
b) the first set of numbers indicates the number of grooves;ISO 9981 pdf download.