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Danny Harvey

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Reply with quote  #1 
One of the things that we cover for a small papermill is this agitator drive.

We had reported that the agitator shaft was flexing a lot in previous months, then found out that the propeller had broken. I don't know the nature of the break but we were on site last Friday and the drive and structure had all been removed and the chest drained.

When we returned Tuesday, the drive was back in place and it looked like this. 

You can hear me in the background trying to get the name of the agitator to tag the video with. You might even be able to hear me roll my eyes when he tells me twice that the equipment name is agitator before I can get the name Machine Chest Agitator out of him. Nothing is tagged at this site but we are now working on it.

Someone on B shift got orders from Production to reinstall the drive with the broken propeller so that they could run some order. It only had to go for 3 days.  When I found it in this condition, it had been running about 12 hours. 

I was opening my mouth to question how long it might run when the last of the four small bolts that were holding the box to the plate failed. The drive spun almost 180 degrees until it ripped the wires loose in a shower of sparks. This is a 40 hp drive at 30 rpm of so so there is plenty of torque to break the 4 bolts used to hold the box to the plate.  They were no more than 1/2" diameter. Only one was found and it had no head.

The Lead Tender ran to the control room and threw the breaker then returned.  He was about to go up on the tank for some reason when I asked if he was sure the power was off. He then decided that given the lack of tagging, he had better get an electrician to verify that there was no loose power. I don't think there was, but there is plenty of reason to take extra precautions here.

It's a dangerous world out there and the further you get into the woods, the worse it seems to get. Orders like this are sometimes issued during B shift when maintenance/engineering management that would prevent this kind of hazard are not around. Sometimes the results of the push for production can be drastic, costly and dangerous.


 
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mp4 agitator.mp4 (6.77 MB, 51 views)

ivibr8

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Reply with quote  #2 
Yikes !  [eek]

That is one agitated agitator.  You are obviously experienced enough to stay clear.  
Two questions:
1. Do you have a picture of its final resting place?
2. How does a broken propeller mix the product?
Danny Harvey

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Reply with quote  #3 
1. Yes. I have attached it.  It was literally just seconds after I stopped the video. I was standing in the same place as before.

2. I'm not sure of what "broken propeller" really means but I think it has two blades and one was missing from the looks of it. I would guess that it provides adequate agitation.

Until it doesn't.

The very frustrated Maintenance Manager said that a short wire is what they call and E-Stop there.

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jpeg agitator2.jpg (121.62 KB, 37 views)

MarkL

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Reply with quote  #4 
Good catch....managing to walk out of there in one piece, the state of that place doesn't really surprise me this happened.

I presume the floor your on, is it the top of a tank? That motion of the motor and gearbox looks like a 2 paddle impeller missing one(paddle/blade)



Alex

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Reply with quote  #5 
Congratulations! Motion amplification without software [biggrin]
Danny Harvey

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Reply with quote  #6 
Mark,

I thought it was a particularly astute observation on my part. This is all pretty much at eye level. I expect you're right about one paddle missing.  Notice that they even went so far as to put three layers of 1/8" red rubber gasket to cushion things. You can see the whole channel frame flexing.

Alex,

Thanks,but now I'm going to need you to sign an NDA. I really don't get the big deal that we make ODS and MA into [wink]
MarkL

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Reply with quote  #7 
Yeah, some of the Bandaids people come up with to try and cure these sort of things.



Sinski

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Reply with quote  #8 
Thats amazing. Funny thing is a couple of years ago I found a fault with our Machine Chest Agitator which is meant to be an important part of the process. The agitator has been removed but a new one never put in place and we run fine without it.
RustyCas

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Reply with quote  #9 
I used to monitor some large agitators and the movement of the gearboxes was fascinating at times.  Never saw one fail though.  As for the torque, I'll have to find the melted rollers from a bearing that failed.  Without that "short cord" E-stop, it takes a lot to kill them.
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Danny Harvey

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Reply with quote  #10 
I wish I had left the camera running for another 10 seconds because it all happened in that time frame.
fburgos

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Reply with quote  #11 
wow.... a killing machine you have there, terrible management, I though only in my plant prouction guys only care about their "bonus" even if it means losing the machine.
Danny Harvey

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Reply with quote  #12 
Despite the obviously poor decision making that led to this, they do have a point.  It should have been fixed long ago.

And in turn in fairness to Maintenance, the manpower and money to fix it should have been provided long ago.

They're trying, though. Lots of improvements have been made, too. A new pulper is being installed and lots of pumps are getting replaced.

And I hope at least two new propellers are on order. One for use and one for a spare for this and the other agitators.
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