HD6E Sprocket loose

I have an HD6E that I have been running for the past few months. Last week I noticed a noise coming from the right rear of the dozer. When I checked the under carriage I noticed that the right sprocket had about ½ inch side to side play. I brought it to the shop and pulled the outer bearing cover. The bearing was good so I broke the track, raised the dozer and inspected the sprocket. It appears the sprocket has become loose. The sprocket nut “keeper” was in place and still had the bolts in it. I removed the keeper and I could rotate the nut by hand. I could tell someone had been working on it before because the nut that holds the outer bearing had a ¼ inch bolt in place of the pin retainer.

Now for the question. Will tightening the sprocket nut solve the problem (2200 ft. lbs.) or will the sprocket need to be replaced? The book that I have stressed that the sprocket had to be tight on the shaft or it will cause premature sprocket failure.

Thanks for the reply mdtractormechanic.

The shaft is tapered. The book said the best way was to press the sprocket, but it could be put on by tightning the nut to 2200 ft. lbs. if a press wasn't available.

oljoe wrote: Thanks for the reply mdtractormechanic. The shaft is tapered. The book said the best way was to press the sprocket, but it could be put on by tightning the nut to 2200 ft. lbs. if a press wasn't available.

That's good to hear that it's tapered. Do you have access to a torgue multiplier? Using one would be the best method to tighten the nut as this is a lot on foot pounds. You could probably rent one at you local tool rental store. It's worth the price of rental. Using a long pipe could work but you stand a good chance of the nut being to loose and ending up like you are now or stripping the threads if you over torgue. Risky at best. I've had to go out and replace several shafts and some sprockets over the years due to the 'pipe torguing method'.

I'm sorry I don't live closer as I have all the tools you need for the job. Good Luck, Joe

I have used the pipe method in the field on older Cummins engines 2 piece crankshafts and a few marine gears, does work if you set the part with a sledge.  I was taught by my dad, he was a A&E mechanic and used it on prop nuts on Douglas DC 3s and 6s radial engines.

Midway through HD6 production, they changed spocket and shaft to fine spline. Many older tractors got the fine splines fitted later on. They say it solved the problem of breaking off the end of the shaft. I think that problem had a lot to do with incorrect torque on sprocket installation, and how the tractors were used. I broke one years back. An oldtimer on AC tractors then showed me the error of my ways; I had been winching big timber with no standing trees to hold the tractor I was chaining the blade to low stumps out front of me. The load transfered to the track frames which were flexing the shaft ends. Never did that again. welded a hitch on front of chassis for any time I couldnt sit on a tree or bank   Mac

By the time we have learned all we need to to run our tractors trouble free Coke, we will be too old to run them!

I got a chance to look at the dozer this weekend. I tried to tighten the nut and discovered that it had expanded to a point where the threads wouldn’t take hold on the shaft. The threads looked good on both the shaft and the nut but it wouldn’t start. I found a nut locally at  Zimmerman’s Tractor that still had the seal with it and installed it on the shaft. The new nut started good and didn’t have any slop in the threads so I tightened it with a big pipe wrench until it was snug. I made a wrench out of ½ inch plate and with a long cheater pipe tightened the heck out of it. I used Mactractor’s method of hitting the sprocket with a sledge hammer and retightened it 6 or 7 times. Each time I hit it I gained a little. The nut didn’t slip on the threads so I think it may be OK.

gemdozer, I checked the sprocket for cracks and there wasn’t any around the hub but I did find a crack between two of the teeth. I ground out the crack and welded it. I forgot to preheat the area so I hope it doesn’t crack somewhere else.

Thanks everyone for the help and advice.

Joe

Good to hear it all worked out.