BS ISO 13050:2014 pdf free download.Synchronous belt drives Metric pitch, curvilinear profile systems G, H, R and S, belts and pulleys. 6.1.3 Pitch length measurement See Annex A for tolerances and Annex B for the relationship between the centre distance and the belt pitch length. 6.1.3.1 Measuring fixture (see Figure 3) The pitch length of a synchronous belt shall be determined by placing the belt on a measuring fixture composed of the following elements. 6.1.3.1.1 Two pulleys of equal diameter, as specified in Table 3, of the proper belt profile and having standard tooth space dimensions. These pulleys should be made to the tolerances shown in Table 3. One pulley shall be free to rotate on a fixed-position shaft, while the other shall be free to rotate on a moveable shaft to permit the centre distance to change. 6.1.3.1.2 Means of applying a total measuring force to the moveable pulley. 6.1.3.1.3 Means of measuring the centre distance between the two pulleys with the necessary degree of accuracy for centre distance measurement. 6.1.3.2 Total measuring force The total measuring force to be applied for measuring belts is given in Table 4. 61.3.3 Procedure In measuring the pitch length o’a synchronous belt, the belt should be rotated at least two revolutions to seat it properly and to divide the total force equally between the two spans of the belt. The pitch length shall be calculated by adding the pitch circumference of one of the pulleys to twice the measured centre distance. 6.2 Pulleys, profile system G 6.2.1 General See Annex C for tolerances. The pulley is characterized by a curvilinear groove profile. This groove profile is defined as the profile formed by the generating tool rack form required to machine- finish the curvilinear profile. The profile is different for each pulley diameter, but can be closely approximated by a nominal groove profile over specified ranges of number of grooves. 6.2.2 Generating tool rack Dimensions and tolerances for the generating tool rack for pulleys with profile system G are given in Table 5 and shown in Figure 3.BS ISO 13050 pdf download.
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