semihermetic compressor stator extraction

As in any maintenance crew, usually is the novice technician the one assigned with those tasks that others are unwilling to do.
Here at the shop, there is a good number of "death" compressors, mostly Copeland Discus, with their stators either burnt or shorted. I have been directed to extract these stators in order to donate them to a local technical school for rewinding practices.
I have been trying to find a way to pull them out of the blocks, but they are really thightly fitted. Does anyone of you know about a method for extracting these babies?

:DHey racktech2008...I see you love working on the semi-hermetics and always get the dirty jobs.:pMy uncle runs the second biggest compressor rebuilder/remanufacture company in South Africa.He did all types of compressors ranging to various sizes.He did do alot of business around the world,especially with the usa.(importing/exporting)

While i was still an apprentice,i used to spend alot of time around his workshop,learning the tricks of the trade.He had really expensive machinery he imported from the usa and germany.From stripping the comps down,skimming valve plates,re-aligning crankshafts etc...that was all done by machinery.

I know extracting the stators by hand needs plenty of energy and clever technique.Unbolting it seems easy,but pulling it out of the compressor housing is another story.:DPractice makes perfect!!!:cool:

Hi springbok. Good to hear from you. You seem to dislike sleeping since it must be about 1:00 am Sunday morning in Scotland.

I just checked another forum I'm member of, and someone mentioned a heavy duty hydraulic stator puller with some kind of device that bites on the stator. As you said, he is talking about very heavy and specialized type of machinery. As this stator extraction task is only a philantropic activity, I doubt my boss would invest in such a tool. I must find another way.

By the way, did you look at my reply regarding the problem I have the other day with a CPC REFLECS communication failure?

Have a good one buddy.

Hi Rack I worked on Copeland for years and still never figured out how to remove the stators

Don't know copeland, but our stators, once the fixing bolt is removed, can be slided out by hand.

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There are two types of internal fixings for semi hermetic stators:

1. A tight slide-in fit with the stator fixed in place with a steel dowel or a bolt and a woodruff key in a slot as mentioned by others.
   These normally slide out once the dowel or bolt is removed. A little easing oil may assist a stubborn fit; for example Carrier (Carlyle) 06E and the like use this method. Normally trouble free if you don’t try to force it.
   
2. A press fit into the casting using a hydraulic press. Getting these out is more complex, but can be done. The manufacturers have hydraulic removers and jigs capable of reversing the forces that forced it in in the first place, but if you lack these, here is an alternative method that is quite crude but effective.

How is the second option done?

You will need:

• The usual personal protective gear (boots gloves etc).
• A pulley block suspended from a secure point and chains capable of holding the compressor.
• An iron bar about 20mm diameter.
• An old mattress.
• A decent sized big propane torch (NOT oxy-acetylene)
• Fire safety kit.

1. Suspend the pulley block securely and lay the mattress on the ground immediately below the pulley block.
2. Strip the compressor of its rotor and other guts on the drive side.
3. To avoid unwanted flare-ups, DEGREASE it.
4. Disconnect the wiring from the connection box.
5. Drill a hole centrally through the old winding loops without damaging the stator block.
6. Pass the bar through it and loop the chains through around the bar.
7. Hoist the compressor body over the mattress; keep it about 50mm above the mattress.
8. (Keep your fire safety gear handy)
9. GENTLY heat the compressor block body all around the outside evenly.

You are aiming to expand the casting with heat so that it parts company with the stator. If you do this slowly you should see the thing start to slid out onto the mattress with the stator hanging on the pulley.

Don't be tempted to assist it with hammers..... just keep the forces and the heat applied evenly all the way round and don't rush it.


.

heat the body up with a torch its the easiest you might have 2 send it in to get it done properly wiyhout damaging it

I can see that ages-old temperature induced expansion/contraction principles are used to perform the stator extraction. Let me get a hand on a propane torch to apply some heat all around the casing and then see what happens. I'll keep you informed. Thank you very much.

To add to Argus's very good coments:

After even heating, several SOFT blows with a RUBBER MALLET perpedicular to the motor shaft over the motor area may help remove those peskey stators.

Steve

Quote:

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Originally Posted by Steve Wright

To add to Argus's very good coments:

After even heating, several SOFT blows with a RUBBER MALLET perpedicular to the motor shaft over the motor area may help remove those peskey stators.

Steve

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Thank you Steve .......... brings it all back.

It's many, many years since I took a hammer of any kind to a compressor..... but mainly in anger.



.

Yes that is really a difficult task.

We have over a years tried various techniques, but till date a perfect solution is far from our reach.

Would a local compressor rebuild company remove it for you? They could keep the old body for parts if it was of no further use to you and useful to them.

Jon

It's been many years since I worked in a rebuild shop, but all of the above sounds familiar. Some types just slide out... for the others, it's puller, torch, hammer, muscle and patience.

Yes I think patience is the key word!!!!

First ever post!
Just back into refrigeration after a long break and getting ready with some dumb questions, but this thread brought back some happy memories of life in the workshop at Prestcold in Birmingham and watching John P hanging compressor bodies on a chain, cooking them with a blowtorch and whacking them to remove the stator (no boots, no goggles, no PPE, this was before H&S!). It always worked and they were subsequently refurbished and sold at an exhorbitant price. Happy days.

gas bottle

Do they still make Prescold?

I used to use them here in the USA and they were great.

They were quiet and ran a long time under harsh conditions.

I think Copeland bought the rights to them in the USA then they just seemed to fade away.

Steve

i used to do this every day,easy! here goes!
First strip the machine,crank ,rods,rotor terminal plate, back foot, everything, then hang it up motor end down. You then need 4 blow torches, get one person to heat either side of the terminal block and the other to heat the 'foot' and the sides, 3mins on the foot then 3 mins on the sides then 3 mins on the foot again. then batter both sides at once with copper mallets and very soon the stator will pop out.
Its important not to heat it any longer than 9 mins or you'll never get it out,if it doesn't come out first time(unusual) let it cool completely and try again. 9 mins is ideal for say a 4 or 6 cylinder machine longer for bigger shorter for smaller.
Hope this helps

Quote:

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Originally Posted by Steve Wright

gas bottle

Do they still make Prescold?

I used to use them here in the USA and they were great.

They were quiet and ran a long time under harsh conditions.

I think Copeland bought the rights to them in the USA then they just seemed to fade away.

Steve

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Prestcold were traded under the Copeland name. Some of the old models still exist but for the most part since the early nineties and with the development of Discuss and Scroll, prestcold type comps are not as common.

Cheers taz.

I spent a few months during my apprenticeship at a company that rebuilt compressors and assisted with quite a few stator removals on carrier 06 compressors, the weapon of choice was the big sievert propane torch that throws a flame about 2 foot long and a big copper hammer as has previously been described. Imagine the surprise we got one day whilst doing this to see a depression start to form on the casting:eek:
The cheeky *******s at the factory had decided to salvage a casting that had been substandard and porous by filling it with a solder of some sort, I'm not sure what it was but that compressor ended up on the scrap pile!!

Quote:

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Originally Posted by chillled

i used to do this every day,easy! here goes!
First strip the machine,crank ,rods,rotor terminal plate, back foot, everything, then hang it up motor end down. You then need 4 blow torches, get one person to heat either side of the terminal block and the other to heat the 'foot' and the sides, 3mins on the foot then 3 mins on the sides then 3 mins on the foot again. then batter both sides at once with copper mallets and very soon the stator will pop out.
Its important not to heat it any longer than 9 mins or you'll never get it out,if it doesn't come out first time(unusual) let it cool completely and try again. 9 mins is ideal for say a 4 or 6 cylinder machine longer for bigger shorter for smaller.
Hope this helps

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Hi chilled.
This reads more like a Cookery lesson, Someone will be refering to the relevant Gas Mark required shortly.
Seriously though I have seen this done a few times and it still never fails to amaze!

On a slightly different note the " rebuilt" Industry seem to love the large MAN-EUROPE Hermetics.
The ones with the inbuilt Klixon / Thermistors. (which take up to 24hrs to reset) as apparently
people return them as faulty)

In this state there is not a lot of work required to rebuild them
Grizzly

Hi,
here some info how to remove the stator,
*ww.dorin.com/jsp/livesite/DisplayDownload.jsp?DownloadId=Smontaggio%20-%20sostitu[/url]

any one know the way to remove stator without damage the stator?

w.l.ong

Quote:

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Originally Posted by w.l.ong

Hi,
here some info how to remove the stator,
*ww.dorin.com/jsp/livesite/DisplayDownload.jsp?DownloadId=Smontaggio%20-%20sostitu[/url]

any one know the way to remove stator without damage the stator?

w.l.ong

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Once upon a time , circa 1983, I had to remove a stator without any damage.
And with out removing any more than the rotor.
I made a kind of hollow cylinder with a flange at the end .
The outside flange diameter was just enough not to touch any winding wire.
The flange was too to the cyl inside to the same offset that outside
The out side cyl diameter was the same as the stator inside diameter.

Then I split it longitudinal and take off about 2 parts about 15 ° , so it allow to enter the stator hollow .

At both parts I weld 2 iron strips , about 1/4 " by 1 1/2 " .
this 2 strip have all round bend to allow a rod to pass trough .

As to allow the 2 splited cyl part to fix to the stator, I made other hollow cyl whose OD was the same as the ID of the first cyl , and the ID just to allow to pass trough the crankshaft and its bearing support

So you firs input the 2 spliced cyl parts to the stator bottom , the input the second cyl , and now you have a solid part engaging the stator.
All this with the compressor vertical with the stator side up.

Then I toke a pipe whose ID was bigger than the stator OD , or the same as the diameter circle of the holes at the block end , and as long as the stator length plus a surplus space , and pass the 2 strips trough it and set the pipe on the block face.
The 2 strip where long enough to allow to put a hydraulic jack on a beam put on the other pipe side .
Then I pass the rod by the 2 eye ends at the strip , and easy take off the stator.

If you want further info I can make a drawing .

Hi DEVITG.
Your extraction tool design sounds very interesting. Definitely I would like to get a drawing of it.

Hi Coldkeeper1, I will do it .

Dear w.l.ong: I tried to reach the link you suggested but was unable to get through. Anyway, I visited the Dorin website and found, in the semihermetic compressor download menu, a file containing three good pictures of the special device they suggest we should use to push out the stators whith the help of a 60 ton hydraulic press. I guess that it can be made in any decent lathe shop. Thank you for the useful info!!!

Here is the link!
http://tinyurl.com/5vlt99