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I apologize, but I did not see your name.

First, the data you attached is incomplete. Please provide spectral data that includes an Fmax of at least 2xGMF (gear mesh frequency). You can calculate the gear mesh frequency by multiplying the rotating speed of the shaft times the number of teeth on the gear. The GMF for the bull gear is the same as the GMF for the pinion. With an Fmax of only 1000Hz, the GMF and harmonics are not visible in the spectral data. Also provide that data with sufficient resolution (6400LOR) so that sidebands around GMF can be distinguished.

Second, the higher amplitudes are associated with the bull gear, which is the input gear, since this is a speed increaser. At G1A, you list an overall reading of 34.2 mm/s (which corresponds to 1.346 ips-pk) and 28.6 mm/s (1.126 ips-pk). The spectral data does not contain that amplitude, so no determination can be offered.

I am eager to see what you can provide.

Thank you for the opportunity.

Jim Carrel, CRL, Cat. III Vibration Analyst

A couple ofobservations...

I see by a page in the docx file, page 5 of 18 specifically, I see running speed of 18542 RPM for the pinion.  I also see the typical running speed of a 2-pole motor on 50 Hz of something around 2985 RPM.  So just running some potential tooth combinations, all with a hunting tooth design I come up with the following possibilities.  Note these are based on the 18542 RPM for the pinion and 2985 RPM for the gear and a hunting tooth combination.

143/23  mesh = 7108 Hz

180/29 mesh = 8962 Hz

193/31 = 9580 Hz

199/32 = 9889 Hz

205/33 = 10198 Hz

211/34 - 10507 Hz

As you can see all these measurements are well up into an area where an accelerometer should be used and the measurement unit in g's.

There are a lot of assumptions going on with my prediction of tooth combination so it might be worthwhile to go back to the OEM for the actual tooth combination.  You might also look for the API gear spec sheet.  Since you have the blower spec sheet perhaps the gear spec sheet also exists and if so it usually shows the tooth combination.

By the way, I took note that the gearset is an AGMA quality 5 and that is surprising for a pinion going 18542 RPM.  But that 18542 came from a balancing record and I have seen many sheets like that in error.


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