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Noknroll

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Anyone monitoring something like this?
Capture.png  Capture1.png 

what AP sets would you use just to capture 1 revolution of the out put shaft?
I have 4 of these to do, Think I'll take my sleeping bag




Danny Harvey

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Reply with quote  #2 
Nok,

What's the motor speed? Do you want one revolution of the gearbox output shaft or of the slewing gear/track?

Depending on the motor speed you're talking in the neighborhood of .1 rpm so about 10 minutes for a rev.

With only one rev, the fft won't work on the low speed stuff so it would be twf only. To get demod, you're really going to need in the neighborhood of a hour per point. With that kind of time, I wouldn't even try velocity. Bring a book.

John may have more to add but VA for the low speed stuff might not be the best way. Maybe oil analysis and inspection by a gear pro might be better. I would suggest making sure that the lube system is in good shape especially for the tilt drives. If they have external oil pumps, I would be sure to check them. Getting oil to the low speed bearings looks like a critical thing.

Is the slewing drive the same as the tilt drives?
John from PA

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Quote:
Originally Posted by Danny Harvey
John may have more to add but VA for the low speed stuff might not be the best way. Maybe oil analysis and inspection by a gear pro might be better. 

Is the slewing drive the same as the tilt drives?


Not a lot to add as far as monitoring.  As Danny says, oil analysis is a viable option.  I am aware that some designs have ports for a glass bulls-eye to enable a visual inspection.  Traditional vibration analysis is close to being useless except for perhaps the input shaft pinion and even that may be a problem.  The "slewing" drive (actually termed the azimuth drive) can sometimes revolve 360°, but not always.  It should be noted that these things often sit virtually motionless as they track a target.  The "tilt" drive (properly called the elevation drive), is usually about 90° of arc (depends on design) so it doesn't even rotate a full turn.

The designs usually are based on shock loads due to high winds, buffeting, etc.  Related, my former employer made the drives for the NASA/Goldstone project.  The antenna was about 210 feet (64 meters) in diameter and weighed 6 million pounds.  In that particular drive the azimuth was only capable of about ±270° of rotation about a reference (note my previous comment "can sometimes revolve 360°, but not always".  You can read about the drive at https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750008665.pdf
MarkL

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https://docplayer.net/164746253-Greetings-microlog-analyzer-users.htmlThere was another paper on work they did with SKF Microlog on one of the Observatory  Telescopes in Chile also.

What about Ultrasound?
VibGuy~5

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Is that Parkes?
Noknroll

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 Danny, John

My Opening post statement about capturing one rev was for the out put shaft not the whole antenna 😉

I am also of the opinion that VA is probably not useful/practical past the 2nd stage and will be discussing with client to try and influence them that way. The motors are 4 pole & 60Hz  I wont bother with velocity past the input and was going to take simultaneous peakvue and acceleration

they monitor oil condition, and have visually inspected gears but no issues, they replaced a noisy lube pump then noticed a new noise which was described as rythmic, I'm putting my money on a beat.

They refer to the drives as Zenith and Azimuth.

Mark 
thanks for the link, I don't have ultrasound gear

vibe guy
yes the picture is Parkes
dnk

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I agree with Mark. I used ultrasound on clarifying tank arms where 1 rev took 45 min. Couldn't get useful data with VA.
VibGuy~5

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I used to do the gold/copper mine there and visited the telescope on the way back one day. Pretty impressive. My brother in-law is an astrophysicist-that's his kind of thing. He would pronounce it 'Paaaaaaarkes' (like the movie)
MarkL

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Quote:
Originally Posted by dnk
I agree with Mark. I used ultrasound on clarifying tank arms where 1 rev took 45 min. Couldn't get useful data with VA.


If you have a instrument capable of doing twf like a UE systems ultra-probe 15000 I think you should have decent results. They have a magnetic sensor that can be attached to the instrument.

I’ve a good contact in ue systems and he’s shown me some impressive slow speed applications he’s worked on, mind you nothing that slow. I’ll have word with him.
Noknroll

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Reply with quote  #10 
Vibe guy
I and another workmate spent a couple of weeks up at NPM doing permanent accelerometer install about 7 or 8 years ago
Dave Reynolds

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Reply with quote  #11 
http://www.uesystems.com/brochures/4Cast.pdf
VibGuy~5

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Reply with quote  #12 
Nok-I did NPM, CVE and Lake Cowal for a couple of years. Cold in CVE in the winter. Dusty, but fun. I checked out the telescope on the way home one day. One big structure
Vibe-Rater

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Reply with quote  #13 
For those that don't know the Parkes radio telescope was instrumental in keeping communication with first moonlanding mission.  Houston was on  the wrong side of the world so could not hear, but Australia could. Anyway fwiw. rgds
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