638 nh round baler problem

Just seeing if anyone has had this problem. Standing looking at the baler the gearbox is in the center tucked up inside a little there is a shaft that goes to the right side on the other end is two sprockets on the end that run separate chains that runs the baler.the outside chain broke yesterday. Thought maybe the Link failed at first. I put the chain back on but it didn't want to fit in part of the sprocket just right I think it got tweaked a little bit.so I tried it again halfway through the first bale I see smoke starting to come up out of the large door that gives access to all the gears and chain on that side.the entire shaft moved to the right sliding off the splines on the gearbox causing the chain to run hard into the bolts that hold the bearing together almost wiping the heads off the bolt that's where the smoke came from.it ruined the chain and bearing. That shaft just seems to be there with nothing really holding it in place like it just runs in place by the chain.im thinking if the chain got tweaked and wasn't riding the sprocket right is the reason it drove it so hard to the right causing all the damage.i think if I would of put on a new chain I would of been okay but I'm not sure.when I put the chain back on the first time everything was still where it was supposed to be no damage to the chain
But why did the chain brake in the first place.it was the master link that failed in the beginning .maybe the Link failed in the beginning for who knows why maybe just came apart.the chain looked perfect no gouges wear Mark's or anything.the shaft didn't move until I put it back together and made half a bale.i think the link just failed then the chain got tweaked when it came apart and caused the damage but I'm not sure anyone ever experience this. Sorry for the long post Rick

the roller is not healed place by the chain. sound like you had a bearing go out and that let the roller shift . only a guess never worked on one

That shaft (#2) is held in place by the lock collar (#29) on the bearing (#23). The bearing is held in place by two flanges (#35). The outside chain (#36 102 links of #60) is bad, the inside chain(#11 57 links of #50) and the sprocket ( I can not see a part number on just the double sprocket. I hope it is not part of the entire shaft #2)it is more than likely shot too. This bearing maybe bad too and spun in the flanges and then wore the edges off them. That would allow the bearing/shaft to walk out. Then the chain failed.

I would replace the bearing/lock collar, flanges, both chains and the sprocket IF it is available separately. Put a new chain on a worn out sprocket will just wear the chain out fast.

Your original problem was either the bearing coming out of the flanges or the lock collar coming lose. This allowed the shaft to move and break the chain. The chain breaking is a symptom not the problem.


Go to this page at Messicks. Then go to Tongue and drive 005.
https://www.messicks.com/nh/57758
NH 638 baler parts list.

Jd the bearing the flanges and are still good the sprocket is still 80% .I went back out to look things over again and I can move the shaft back and fourth on the gearbox it looks like that coupler is about three inches long or close to it there is a grease fitting on both sides of the coupler directly in the middle kinds reminds me of a overriding clutch on a older tractor shouldn't this coupler be held in place somehow

Thanks for the parts list jd I just now seen it at the bottom of your reply lol

The shaft is free floating on the gearbox. There is no side load IF the bearing is in place. The shaft can not move if the bearing is locked to the shaft and the bearing mount is still sound.

Thanks jd that's what I was trying to figure out if it just floated or was fastened in place somehow