Gearbox Noise Measurement Units

[artbuc]

Manufacturer just sent me a new box which they claim was 100% quality checked (see previous thread). The documents say this unit ran on the dyno at 7 Pc/M^s-2 compared to a standard of 10 Pc/M^s-2.

Does anyone know what units these are? I did some research and found that gearbox noise is sometimes measured in acceleration units such as meters per second squared. Perhaps that is what M^s-2 means? Sound pressure is also measured in pascals but the abbreviation for pascal is Pa, not Pc. Maybe the document has a typo?

 

[Clyde38]

Maybe a typo, but Pc is the abbreviation for Parsec.

http://www.gordonengland.co.uk/conversion/sidef.htm

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http://www.linkedin.com/in/clydehancock

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[tbuelna]

artbuc,

Generally, when acceptance testing a gearbox, you're looking at specific frequencies and modes. These are usually gear meshing frequencies (or sometimes rolling element bearing passing frequencies). Each gear mesh will have a specific meshing frequency at a given input speed, and if there is excessive vibration being generated at that frequency it's usually a good indication of problems with one of the gears in the mesh. Housing mounted accelerometers are usually used for data acquisition.

Measuring radiated sound pressure is a less direct method of doing the same thing, but would not require instrumenting the gearbox.

Hope that helps.
Terry

 

[hydtools]

Looks like a mis-typed capacitance accelerometer sensitivity
pC/ms^-2, picoCoulombs per meter per second squared.

Ted

 

[MikeyP]

Sometimes pc is used for percent, but I can't see it helping you here. Go back to the supplier and ask.

M

--
Dr Michael F Platten

 

[tensor47]

Hi, this is definitely the sensitivity of the accelerometer used in the vibration measurement. 10 is a very standard sensitivity.
Nothing to do with the actual vibration, as this is normally all allowed for in the measurement chain that leads to the waveforms and spectra in g's or mm/s etc.