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Noknroll

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Anyone here doing mobile equipment with portable data collector.
Got a phone call to check an excavator that's making a noise.....I know.......thats all the details I got. I was wondering if anyone had a basic route for a machine they could share. Having not done any mobile equipment before any tips are most welcome.
Thanks
RustyCas

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Reply with quote  #2 
For unknown machines I usually set up a “group” of points with several types of collections: P1 (standard), P1Z (high max), P1P (peakvue), P1L (low fmax), etc. Grouping these in CSI I get all the data with one key press. Then I duplicate the group for as many points as I think I’ll need (P1, P2, P3, etc). I should make up a log sheet to reference each point (but I don’t). If I were really with it, I’d make up some small laminated cards labeled P1, P2, etc and then take a photo of the sensor mounted at each point with the card in the frame.
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George D

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Reply with quote  #3 
My minor experience with our emergency diesel generator, and friend’s airplane engine. I include our emergency diesel because it’s a four stroke engine, similar I assume to your mobile equipment?
Dramatically dominated by 0.5x of crankshaft speed... or, piston firing frequency for a four stroke engine. On our diesel engine, I guess some people thought I could pick out a bearing defect frequency on an auxiliary pump? I really don’t think I had any chance? At some survey locations, a block mounted water pump, it begin saturating the Wilcox 793 transducer... evidenced by an emerging ski slope. The dominant spectral evidence was a broad series of half-X harmonics. I asked them not to count on me.
A friend asked me to help him figure out if the high vibration he noticed on his private airplane was due to an imbalanced prop. One of the coolest vibe things I’ve ever done? Sitting in the cockpit of his little airplane, on the concrete just outside his hanger, with transducers mounted to the engine block and cables to my vibe box inside the cockpit. Again... 0.5X. So bad it rattled one of my little Dytran accels off it’s glued-on mount. I guess I helped him? An imbalanced prop would’ve been high 1X, which it was not. I guessed a connecting rod?... with clearances opening up at either a wrist-pin or crankshaft? I guessed it was slamming out the clearance every time the piston fired? I never found out for sure?... he took it to a shop and had the engine swapped.
Pretty random experience huh? You did ask for anything we had? Thanks for asking...
ivibr8

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Reply with quote  #4 
Nok
I don't have a lot of experience with mobile equipment but I like Rusty's approach. I'm sure lots of things go through your mind when planning for something like this so having a pre-loaded "run" list (or whatever its called in your particular system) that covers most typical problems is wise.

I would also ask your client for more information before you head off (is the source of the noise fairly evident?  is it continuous or only during heavy "loading"? Do you have another similar machine for comparison?, etc.). 

Finally, if your system has the ability to record the raw data (write to file?) that is another tool I found to be helpful as you sift thru the data during post-processing and not wishing you  had taken additional data.

If you do this job, let us know what you found and any advice you would give 

Regards
Jim P
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Reply with quote  #5 

Emergency diesels, yes got that. Latest a set of 3 brand new at a hospital where one had higher levels at the end where the camshaft drive gears were and a lot of particles in the oil.....
Another brand further back in time sold mounted in containers and larger, had a lot of 1xRPM and could nicely be balanced at the big flywheel, varying 50g to a couple of 100g.
I don't know if combiners/harvesters also get in the similar rating but they were just not cleaned after like 13 years of operation...... 
Only with caterpillar tracks I remember are way back and green APC's and w/o giving up to much secrets, they follow ISO standard, if above 17mm/s or so on the drive train they came back from the woods in 
a towline after a rescue vehicle, less than 3mm/s they run for ever.... Real funny I thought at the time.

 

 

 


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Shoveldr

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Reply with quote  #6 
It depends on the type of excavator, I spent a lot of time on electric cable shovels, which are variable speed motors with multiple reduction gearboxes.  Variable speed, variable direction and variable load.  A pain in the ass, but doable.

The smaller excavators are primarily hydraulic, so you will have a diesel engine and a hydraulic power unit.

If it is the former I can give you some advice, if it is the latter I haven't done much of those.
Noknroll

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Reply with quote  #7 
Thanks for all the responses, each of them gave me something i hadnt thought of.
My basic plan was to go over the machine in manual analyze and live mode looking for high amplitudes in the location of "the noise"
I do like Rustys approach.
I've yet to talk to the guy who asked to have the analysis done, hopefully I will get to do that beforehand and get a better idea on how to approach the job.
MarkL

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Reply with quote  #8 
I think it's important to verify if it's a cable shovel or a hydraulic excavator/track hoe as the Yanks call them.




Noknroll

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Reply with quote  #9 
well so far I've left voice messages and texts to the ph number I was meant to call, to find out about the job but had no reply. So at this stage the job which will include a 2 hour drive each way aint happening. I was sort of looking forward to something out of the ordinary and out of the comfort zone
Shoveldr

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Reply with quote  #10 
A trick I've used in the past when something is "making noise" is to hook up a microphone or noise meter to my analyzer and take an FFT to see what the frequency is they are hearing.  It may help track down the fault.  I will admit I have had mixed results with this.
Walt Strong

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Reply with quote  #11 
I typically analyze a reported machine "noise" with sound pressure measurements with a microphone, and I interview the operator or mechanic before initiating vibration measurements. The interview can reveal when sound/noise started, machine operation/task, steady/intermittent, sounds-like, possible source, and recent/related maintenance. I consider this very important strategy for a situation where machine is unfamiliar or complicated.

Walt
Noknroll

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Reply with quote  #12 
Quote:
The interview can reveal when sound/noise started, machine operation/task, steady/intermittent, sounds-like, possible source, and recent/related maintenance. I consider this very important strategy for a situation where machine is unfamiliar or complicated.

Walt
That's the exact approach I take, also the same approach I took when I was on the tools as a troubleshooter/breakdown mechanical tradesman. Often the right questions can take you straight to the problem.
Rang

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Reply with quote  #13 
First place I look is under the operators seat for empty tins of VB...
Sinski

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Reply with quote  #14 
Quote:
Originally Posted by Rang
First place I look is under the operators seat for empty tins of VB...


[rofl][rofl][rofl][rofl]
OLi

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Reply with quote  #15 
Would that not lower sensitivity to vibration?
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