BS ISO 155 pdf free download

BS ISO 155-2019 pdf free download.Belt drives — Pulleys – Limiting values for adjustment of centres.
This document specifies the limiting values for the adjustment of centres of two transmission pulleys.
It is applicable to:
— crowned pulleys for flat belts;
— grooved pulleys for V-belts, either single, multiple or joined;
— grooved pulleys for V-ribbed belts;
— toothed pulleys for synchronous belts.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
一IS0 Online browsing platform: available at https://www.iso.org/obp
一IEC Electropedia: available at http://www.electropedia.org/
4 Symbols
For the purpose of this document, the fllowing symbols apply.
Limits of small flat pulley diameter
Limits of large flat pulley diameter
Groove pitch of a V-ribbed pully
Nominal centre distance
Lower limit for the adjustment of centre distance
Upper limit for the adjustment of centre distance
Factor related to the pulley dimensions and tolerances
Factor related to belt length tolerances
Nominal belt length
5 Specifications
Limiting values for adjustment of centre distance are specified in terms of factors i and s which are respectively subtracted from and added to the nominal centre distance, E (see Figure 1).
where
S1 is a factor related to the pulley dimensions and tolerances;
S2 is a factor related to belt length tolerances;
S3 is a factor related to flat pulley crowning;
S4 is a factor related to elastic properties of the belt.
Factors with subscripts 1 to 3 determine the centre distance adjustment necessary to install a belt onto the pulleys and to readjust working tension.
Factor S4 determines the centre distance adjustment necessary to maintain correct operation of a belt under the influence of belt extension and dimensional wear.
These limiting values should be considered by the belt manufacturers as maxima, and by the designers and makers of the machinery as minima.
6 Factors
The values of the different factors are given in the following tables:
一for factor iand factor s, see Table 1;
一for diameter tolerance for flat pulley, see Table 2;
一for datum widths for V-belts, see Table 3;
一for effective widths for joined V-belts, see Table 4;
一for Groove pitch for V-ribbed belts, see Table 5;
一for values of i1 for synchronous belts, see Table 6;
一for values of S4 related to belt material, see Table Z.BS ISO 155 pdf download.