Problem with auger/ auger extension/ coupling grinding coal

I have a 1950's GJ 52 stoker which I'm trying to put into operation. I intend to use it with bit coal, but first, I'd like to burn up the buck anthracite that I was given when I bought it. Everything is great, works well and the boiler is very solid, except I'm having one major problem. I'm using a three foot auger extension that came with the unit.

The problem is this: The buck coal starts out as, well, buck anthracite of good quality in the bin, unfortunately, it soon becomes powder that puts the fire out in the retort. I'm grinding the hell out of the coal between the bin and the retort, and I don't really know why. I've used worn out augers with softer bit coal and never had anything like this - it literally pulverizes the coal. The auger extension looks good, no sharp flights and the stoker auger is in similar good shape. The auger tubes are clean with no obstructions or rough welds. I have the auger protruding into the coal about 5", which, I do not feel is excessive, once again though, my experience is with bit coal.

There are three places that, as I see it, could potentially be the problem:
1. The auger extension may not have flights at the exact same pitch as the OEM auger in the stoker? (appear with initial measurements to be close or the same)
2. The auger extension tube may be slightly larger ID than the stoker auger tube (with a tape they appear the same, but when I find my calipers I will know for sure)
3. The coupling design - I put the pipes tightly together and pulled them apart with the same result, however, the GJ coupling design (see pics below) leaves bold heads/nuts protruding into the coal space and the coupling itself is larger than the auger shaft. In addition, the space between the last flight in the auger extension and the stoker auger seems quite large.

stoker pipe - ID-2 1/4" auger - 2 1/8"

feed pipe (extension) 2 1/4" auger (extension)- 1 15/16"

I appreciate any and all ideas, suggestions etc. to solve this problem - better ways to couple the auger shafts, or similar experiences and solutions. Thanks all in advance.

The coupler is my first suspect. Those bolt heads will really grind the coal. If the steel pipe is pitted inside that will also cause grinding.

What size are the auger flights and the pipe ID?

The steel pipes are rusty outside but mostly smooth inside.

Measure w/ calipers
stoker pipe - ID-2 1/4" auger - 2 1/8"
feed pipe (extension) 2 1/4" auger (extension) - 1 15/16"

The coupler between the two flights has a bolt in it?
How about trying a flush-mounted shear pin in the coupler, with both ends peaned so it doesn't fall out.

It doesn't take much roughness inside the pipes to cause grinding...the bin end is usually the first to get chewed up. Try running coal up through the bin pipe with coupler removed and see if it is intact when it gets to the joint in the pipes. (that idea is courtesy of member Lsfarm).

Well what do you know, Im having the same problem only mine burns rice perfectly and when I put my Bit coal in it runs 2-3 days and then dies out, the pot and auger tube are full of fines.

Auger diameter --- Tube Dia --- pitch --- flight thickness

pot auger 2-5/8" --- 2-3/4" --- 2-1/4 --- 3/16"

Bin auger 2-3/8" --- 2-1/2" --- 2-1/4 --- 1/4"

We are looking for a larger bin auger and I am going to (with help) git rid of the bolt heads and add a piece of flighting at the coupler.

This thing is driving me nuts, but I am confident it will eventually work.

Good Morning Berlin, did you test the bin auger? just leave the coupling open and run the auger,into a 5gal pail, and see if it's grinding the coal or not..?

A suggestion: go to a TSC, or good hardware, get a 5/16" x1" pin with SS cotter pin. use this to hold the augers together, the much smaller pin head and cotter pin should not grind up the coal as much. Or cut off the existing bolt's extra threads, and use a 4.5" hand-held grinder to grind the leading side of the bolt head and nut smooth, so that it won't present a sharp or aggressive edge to the coal as the auger rotates.

Greg L

Could you use some small, fine-thread set screws? Roll-pins also came to mind.

I made up this piece of flighting, for BKsaun to use to fill the gap in flights between his pot auger and bin auger.
I have to say, that bending that steel was NOT easy!! I really needed a second set of hands to run the
torch while I used two hands on the steel bar.. it is VERY difficult to keep the flight at 90* to the auger shaft.

But I think with BK's soft coal, an uninterupted flight is vital to reduce or eliminate the grinding of his Bit coal..

Berlin, I'm betting that the inside of the auger tubes are rust-pitted, and causing most of your grinding .

Greg L

well, I guess we're both in the *censored* with these GJ stokers. I'm about to rip the thing out and throw a different stoker - even a different anthracite stoker in the boiler.

Update: I tried bit coal (sized much the same as buck anthracite) and it powdered it instantly - couldn't even START the fire, nevermind getting it going. Apparently, the guy I bought it from didn't use the auger extension for this reason - he couldn't burn buck anthracite in it with the extension, explains why the auger extension is basically in new condition. So he just put the pot auger directly into a drum against the boiler. It would burn rice anthracite ok through the auger extension, but he wanted to burn buck, so he ditched the extension. I do not know if this is the OEM joint design or not - I am not very familiar with the various anthracite coal boilers and their auger designs.

I ran the stoker with the coupling open (once I stopped the tube from twisting) and the coal appears to be more or less intact arriving at the coupling. I did this with bit pea coal (which ground up worse than the anthracite buck). I thought these things were designed for buck anthracite, hence the large auger tube diameter?

Since it appears that I agree with bksaun, that it is the coupling, how do other mfg'rs with small auger shaft diameters have their extensions coupled? is the coupling itself flighted? no bolts? Are there any other flexible coupling designs that work better in this application?

You're both right, the auger extension tube is, upon further inspection, pitted a bit internally. I remain convinced that most of my grinding is being done by the joint, however.

It's important with those couplings not to exceed a certain angle. I see your coupling is missing the ball part of the ball in socket. I I R C, the manual states that the angle isn't supposed to be more than 15 degrees.

Those couplings were a major wear item also. Looks like you need a new one. Dan's machinery in Carbonedale, Pa. is the guy to talk to. The last two G.J.'s I did had almost new coupling and they worked flawlessly.

Scott, I believe you were the one that gave me Dan's info a few years back...I had it written on a note card and filed with my stoker parts info.

General Machine, 412 Keystone Ave, Peckville PA. 570-383-0990

Berlin,

just a thought but 1/4" difference might be too much betwween the the auger and tube.

Im working on mine today.

Bk