Sign up Calendar Latest Topics Donate

  Author   Comment   Page 2 of 2      Prev   1   2

Sr. Member / Supporter
Posts: 216
Reply with quote  #16 
I haven’t had trouble with a UE gun and the pinpoint head listening to couplings. Use the same set up for the local disconnects and other electrical boxes.


Posts: 22
Reply with quote  #17 
John from PA:  That was a really helpful link.  I will ask if the client is inspecting and repacking the couplings every year at least.

Danny:  I will ask them to clean the inside of the guards every time they perform this PM so that we can tell if the coupling is losing grease.

Sinski:  It seems like this is definitely grease related.  It did show a one times and a two times.

Dnk:  I think number of teeth times running speed would be a good indicator, but I think in this case, we got to it after the coupling locked up.  I will look back at older data to see if and when it would have shown number of teeth times running speed.  I have no idea how many teeth the thing has though.

Shoveldr:  that's pretty much what ours are showing.  High 1x and 2x in the radial and even axial.

I am going to look at the data more today.  It seems like they may have issues on a few of these couplings.  This could indicate their PMs are either not being performed, or they are not being performed correctly.


Avatar / Picture

Posts: 1,810
Reply with quote  #18 
I see very few gear coupling problems, but don't see a lot of gear couplings anymore, so... To the excellent comments so far, I'd add that "listening" to the vibration signal (if you have that capability) is very handy for any potential metal-on-metal situation. Coupling problems show up particularly well at the drive-end axial positions. Often the most useful vibration information is broadband "noise" which is often overlooked in our focus on clean spectral peaks, especially when there are a number of interesting peaks to be evaluated. Sort of "can't see the forest for the trees" sometimes.
"The trend is your friend"

Avatar / Picture

Sr. Member
Posts: 1,121
Reply with quote  #19 
Originally Posted by John from PA

In light of coupling guards and ambient background noise, I'm surprised this is a viable technique!  I would suspect as well that it is limited except if you have carefully trended data.

I've picked up noisy idler roller bearings at 60-70 ft away with airborne ultrasound above the bangs and smashes of a quarry environment with rock falling and rattling on belts etc, the high-frequency noise is quite distinct, I would imagine the high-frequency noise from the friction at a bad coupling would produce the same, Jingle a set of keys in front of an ultrasound instrument and witness the racket....totally different sound to the ambient 'key bunch jingle' you are accustomed to.
Walt Strong

Sr. Member
Posts: 889
Reply with quote  #20 
"In light of coupling guards and ambient background noise I'm surprised this is a viable technique!  I would suspect as well that it is limited except if you have carefully trended data."

I use a remote 1/2" diameter sensor on a flexible gooseneck to reach under solid metal coupling guard or just aim through open mesh guards. Trending is not necessary, and I have used this method for many types of couplings at various speeds. Background noise (ultrasonic) can be an issue, but usually changing microphone position avoids background from direct and reflected sound paths.

I am sorry to redirect away from OP question about vibrations, but usually there is only indirect vibration evidence of a coupling problem after eliminating the usual suspects such as rotor balance, bearings and shaft misalignment.

Previous Topic | Next Topic

Quick Navigation:

Easily create a Forum Website with Website Toolbox.