strange noise atlas copco GA160

[fabricioborges]

we have an atlas copco GA160 compressor that recently made a strange noise in the gearbox during the relief phase. when it comes into charge the noise disappears. Gearbox and electric motor bearings have already been replaced, but the problem persists. can anyone give any idea of the cause of the noise? thanks.

 

[chicopee]

Was the question raised with Atlas Copco Reps?

 

[fabricioborges]

yes, they themselves replaced the element, gearbox and yet the noise continues. It all started in a preventive maintenance 24000 h. After installing the new gearbox elements and gear we performed tests and checked the noise. Electric motor bearings have also been replaced.

 

[Strong]

Is the noise related to pulsation frequencies or gear tooth mesh frequencies? Spectrum analysis from microphone is needed. Can the sound pressure from microphone be correlated with vibrations from accelerometer?

Structural natural frequencies and looseness (rattles) can amplify vibration sources and radiate noise. Typical issues can be from sound enclosure panels, coupling guards, machine component mounts, pipe supports and brackets, and air silencers.

Check for air leaks in the relief (bypass) line. Check for internal damage to discharge air silencer (in present).

A directional microphone in combination with spectrum analysis can help pinpoint location of noise source. Vibration measurements, ultrasound measurements, audio stethoscope, and finger touch can also help pinpoint location of noise source.

Walt