STUCK IMPELLER???

[cmysix]

I thought I might get your attention, I am a millwright I take care of a water treatment plant. I have a slurry pump with a bad bearing, I can not effect repairs UNTIL I remove a latex rubber covered impeller from the shaft that the bearing is on, The impeller is $2000 and the shaft is $2500, I have tried to remove the way that the MFG suggested, no go, can't heat it I'll destroy the impeller(I may have to) QUESTION? I can get to a small portion of the shaft before it passes through the back half of the rubber lined pump housing, do you think dry ice, if I can get blocks about 2 inches thick rested on the shaft would get it cold enough to shrink the shaft, to break it free? I'm also going to ask the local air gas guy if there a way, I can apply liquid nitrogen to it.

 

[itchyTF]

Would the cold mess up the rubber lining making it brittle?

 

[cmysix]

Don't know? but where I would apply the cold would be directly on the shaft, the back half of the pump case would shield the rubber liner and impeller, trying to do the reverse of heating the impeller(if it was just steel) shrink the shaft inside the impeller, even a couple of thousands might break it free?

 

[Sniperhandle]

It would help if you put up a photo. Just wipe the Turds off first!

 

[Knotwild]

Preface: I'm a farmer and I have 0 experience compared to others on this forum. But this is interesting and I hope to learn something.

 

[cmysix]

I will take one in the AM, it is a "drinking water" plant no turds. a silica sand slurry mixed with alum and a substance we call poly. it is amazing how little wear on the latex rubber liner and impeller, if it was badly worn I would have no problem destroying it.

 

[cmysix]

Preface: I'm a farmer and I have 0 experience compared to others on this forum. But this is interesting and I hope to learn something.

I have chain breaking tools from Smith tool in Kansas, learned about them from the farmers in SD when I lived there.

 

[Richard Jones]

I heard a story about my grandfather, who ordered a + shaft and a - collar for a very large motor that basically ran everything in the plow handle factory. Heated the collar and packed the shaft in dry ice and drove it home. The dry ice may work. Good luck with it, and please post your results.

 

[X Count]

Make up a split plate to go behind the impeller that has a hole in the middle to suit the shaft diameter. Bolt the split plate together and then attach your puller setup to that plate so your pulling against the centre of the impeller. Put tension on it, soak with your favourite penetrant, more tension and give your puller a few firm taps on the jacking bolt. Depending on the size you might be able to do this in a hydraulic press. I doubt you'll get enough temp difference in the places it really matters to get it apart. Pressure, penetrant and shock usually works.

 

[jackieschmidt]

I have a lot of experience removing parts with interference fits.

first, how much interference fit does the impeller have on th shaft? What is the manufacturers recommendations that you tried but ailed.

As for shrinking the shaft. Rent a bottle of liquid nitrogen. On the bottle you will see a valve for gas and liquid. Attach a hose to the liquid fitting. The other en of the hose will have a m piece of pipe that will fit in the space where the exposed shaft is.

Turn on the bottle and use the pipe just like a torch on the shaft.

Whether the shaft shrinks enough depends on the amount of interference fit.

 

[Knotwild]

I have chain breaking tools from Smith tool in Kansas, learned about them from the farmers in SD when I lived there.

I love old tools. I have used various chain breaking tools. I regularly use an old New Idea one row corn picker.

 

[Walt Krafft]

If you can drill a hole down the center of the shaft inside the impellor, liquid nitrogen might work to break it free.

 

[cmysix]

I love old tools. I have used various chain breaking tools. I regularly use an old New Idea one row corn picker.

for chain breakers there is nothing like smith tool, their not old, it a hudderwright colony, kinda like the Amish but with machine shops, they make rivet tools for combines too.

 

[cmysix]

I have a lot of experience removing parts with interference fits.

first, how much interference fit does the impeller have on th shaft? What is the manufacturers recommendations that you tried but ailed.

As for shrinking the shaft. Rent a bottle of liquid nitrogen. On the bottle you will see a valve for gas and liquid. Attach a hose to the liquid fitting. The other en of the hose will have a m piece of pipe that will fit in the space where the exposed shaft is.

Turn on the bottle and use the pipe just like a torch on the shaft.

Whether the shaft shrinks enough depends on the amount of interference fit.

The impeller is actually threaded on, you put a J wrench on the flats on the shaft and then turn the impeller to the left, if you go to the right then you can bang the Jwrench on the frame and that shock is supposed too break it free, PER THE MFG, it ain't happening! I have a very nice strap wrench, wrapped around the impeller and using a heavy brass hammer and a 3 foot pipe on the handle for leverage and the hammer for shock, no go! I think I'm gonna try the nitrogen, so I can get a small bottle from air-gas? welding gas supply?

 

[cmysix]

Make up a split plate to go behind the impeller that has a hole in the middle to suit the shaft diameter. Bolt the split plate together and then attach your puller setup to that plate so your pulling against the centre of the impeller. Put tension on it, soak with your favourite penetrant, more tension and give your puller a few firm taps on the jacking bolt. Depending on the size you might be able to do this in a hydraulic press. I doubt you'll get enough temp difference in the places it really matters to get it apart. Pressure, penetrant and shock usually works.

Threaded shaft.

 

[cmysix]

I heard a story about my grandfather, who ordered a + shaft and a - collar for a very large motor that basically ran everything in the plow handle factory. Heated the collar and packed the shaft in dry ice and drove it home. The dry ice may work. Good luck with it, and please post your results.

I have been around a few minutes, early eighties side of the Ohio turn pike Kenwoth cabover, Cummins 290, in Chassis major right on the side of the road me and my Uncle George, everything but the cam 3 heads, fuel pump, grind the head flat on a 1/4-20 almost flat and roll the main bearings out, new ones in, December right before XMAS, wrist pins in the snowbank, pistons in a half a 55 gallon drum of oil heated with a rosebud, pull a piston out rod in , and very quickly the wrist pin! Printing presses the inside bearing races out with a weld bead to shrink them and new ones in with a CO2 fire extinguisher to freeze them.

 

[rwj]

If the impeller has a hub, could it have been drilled for a drive pin or set screw as part of a previous repair?

 

[WSnyder]

can get a small bottle from air-gas? welding gas supply?

Dry N2O (nitrogen gas) from a welding supplier or HVAC distributor is a different beast than LN2 (liquid nitrogen) and won’t do the same thing. You could get CO2 with a siphon tube from your gas supplier and use liquid CO2 on the part but it won’t be anywhere near as cold as LN2.

 

[Dusty Stevens]

Use a lead hammer. All maintenance men should have one. Its the only hammer ive seen that will bend a pipe wrench

 

[Bottom Fodder]

Back in my younger days I worked on a lot of pumps and some of the shafts were tapered and we used a pulley puller( that what the dimple in the end of the shafts for) after soaking with Kroil the same Kroil that I now clean my barrels with, I’ve also seen shafts that were threaded some with left hand threads And some straight with key way. They can be a pain sure glad I’m retired. I’m going back to bed this reminds me to much having to work for a living