BS ISO 5294:2012 pdf free.Synchronous belt drives – Pulleys.
BS ISO 5294 specifies the principal characteristics of synchronous pulleys for use in synchronous endless belt drives for mechanical power transmission and where positive indexing or synchronization is required.
NOTE These drives have been known under various names in the past, for example: timing belt drives, positive belt drives, gear belt drives.
The principal characteristics include:
a) tooth dimensions and tolerances;
b) pulley dimensions and tolerances;
c) quality specification.
As far as dimensions are concerned, the pulleys specified in this International Standard are used interchangeably with the belts specified in ISO 5296.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 254, Belt drives — Pulleys — Quality,finish and balance
ISO 1101, Geometrical product specifications (GPS) — Geometrical tolerancing — Tolerances of form, orientation, location and run-out
ISO 5296, Synchronous belt drives — Belts with pitch codes MXL, XXL, XL. L, H, XH and XXH — Metric and inch dimensions
3 Tooth dimensions
3.1 Involute teeth
3.1.1 The involute tooth profile results in different dimensions for each pulley diameter. Therefore, to specify the involute tooth dimensions would require a very voluminous table. For this reason, as well as because of the difficulty in specif’ing the curved side of an involute tooth, dimensions are specified for the generating tool rack required to produce the involute tooth.
3.1.2 Dimensions and tolerances for the generating tool rack for synchronous pulleys with involute teeth are given in Table 1 and Figure 1.
3.2 Straight-sided teeth
3.2.1 Involute teeth are normally recommended for synchronous belt drives. Since straight-sided teeth are in use, their specifications are also included.
3.2.2 Dimensions and tolerances for straight-sided teeth (see Figure 2) are given in Table 2.
3.3 Pitch-to-pitch tolerances
Tolerances on the amount of deviation of pitch between adjacent teeth, and on the summation of deviations within 90° arc of a pulley, are given in Table 3. This tolerance applies to the distance between the same point on either the right or left corresponding flanks of adjacent teeth.BS ISO 5294 pdf download.