![]() There are 4 I thnk so I'll have to post them separately. These attachments were sent to me by a Gates engineer and will provide some useful information. ![]() We never experienced that but I'm told that it is fairly common. The concern about not enough tension is centered on the belts tendancy to ride up in the grooves causing a kink in the back of the belt and a straight, cross-longitudinal break. I definitely concurred with the mechanics that either of these numbers was way too high. The recommended frequency from the mixer manufacturer was 47 hz and from Gates it was 57 hz. calculate Design Power Select a service factor from the table page 92. (I no longer work in that plant due to budget cuts but understand that they have had several similar failures since I left.) The frequency that they used as a standard was 32 hz. tHe MARk oF engineeRing excellence Torque Drive PLUS 3 Premium synchronous belt The Compact, Quiet. After tensioning and a period of monitoring the vibration, we then measured the frequency of the belt and they started using that as a standard with apparent success. Since ths had been an ongoing problem with about 8-10 failures in the 2 years since they had started using the sonic tensioning method, they decided to go back to using the mechanics judgement which had served them so well in the past. Their overhung load calculations closely matched mine which greatly exceeded the gearbox manufacturers. I contacted Gates directly and had their engineers perform all the overhung load calculations and make their recommendations regarding belt frequency and they came up with an even higher number. I had them take the reducer out of service and found that the inner bearing of the low speed shaft was being ground to powder. Shortly thereafter, I began to measure harmonics of the concentric shaft gear reducers output shaft speed with some ugly impacting. and the mechanics were commenting that the belt seemed way too tight but did as they were instructed and cranked it down until the proper frequency was measured with the sonic belt tensioner. In one case on 8 large mixers this method was being performed exactly to the mixer manufacturers specs. In measuring the length of a belt, the belt should be rotated at least two revolutions of the belt in order to (a) seat the belt properly in the pulley grooves, (b) divide equally the total force between the two strands of the belt, and (c) determine the midpoint of the center distance travel of the movable pulley which shall define the center distance.Be very careful using the sonic tensioner particularly when it comes to non-catalog belt drives. Measuring forces for the standard belt sections and widths are shown in Table 13. Any pair of equal diameter pulleys of the proper pitch and manufactured to the specifications shown in the “Synchronous Belt Pulleys” section may be used for measuring provided the clearance between the theoretical belt tooth width and the groove width of the measuring pulley is not less than the minimum values shown in Table 12. The fixture is shown schematically in Figure 9. Recommended measuring pulley dimensions are shown in Table 12. One of the two pulleys is fixed in position while the other is movable along a graduated scale. The pitch length of a belt shall be determined by placing the belt on a measuring fixture comprising two pulleys of equal diameter, a method of applying force and a means of measuring the center distance between the two pulleys. WIDTH TOLERANCE.īelt width tolerances for all belt sections are given in Table 11. For fixed center drives consult the belt manufacturer. The belt length tolerances shown in Table 10 apply to all belt sections and represent the total manufacturing tolerance on the belt length. Standard belt widths and width designations are shown in Table 11. Standard belt pitch lengths, belt length designations and numbers of teeth are shown in Table 10. The tooth dimensions for double-sided belts are identical to those of a single-sided belt. Table 9 and Figure 7 show the nominal tooth dimensions for each of the standard belt sections. Table 8 gives the Standard B NOMINAL TOOTH DIMENSIONS. STANDARD SECTIONS.īelt sections are specified in terms of “pitch”. The nomenclature for double-sided belts will be the same as for single-sided belts with the addition of the prefix “D” in front of the belt section – Example 300DL075. For example, an L section belt 30.000 inches in pitch length and 0.75 inches in width would be specified as a 300L075 Synchronous Belt. The digits following the belt section designation represent the nominal belt width times 100. The first digits specify the belt length to one-tenth inch followed by the belt section (pitch) designation. Synchronous Belt sizes are identified by a standard number.
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