One of the UJT yokes on our Kubota tractor has failed, one of the 'arms' is broken so no longer retains the needle roller bearing.
Is there any sane way of repairing this as replacements seem nearly impossible to find. It's a bit of a strange design as the yoke goes direct onto a flanged shaft (i.e. it has an internal spline) so finding a non-Kubota replacement is unlikely. However if anyone can recommend suppliers of (small) UJTs with splined connections I'd be interested.
Possibly cast iron?
When you say broken, do you mean a brittle fracture or something else?
Photo?
Cast iron can certainly be TIG welded with the right rod and some skill. I'm not sure if it can be silver soldered. Maybe SG can be, not sure about grey. Google is ambiguous.
If it were mine (and not having TIG) I'd probably try silver soldering. Obviously, you might need to bore out and sleeve the bearing housing afterwards, or perhaps see if a bigger bearing can be fitted. Failing that, might it be possible to cut off the splines and graft them on to something else?
whatever you do don't give us enough information
It will be forged. Probably duff post heat treatment. It will be a hard one to fix/weld. The reason for the splined shaft is that UJs do not rotate at constant spee d when out of line and axial movement comes in. The spline allows for this . I should concentrate on getting a replacement part.
On reflection I'm sure you are right about forging. But also on reflection isn't it more likely to be a metallurgical defect than heat treatment? That's why a photo would be interesting.
Indeed (but we like them, don't we).
although you only need one on the "intermediate" bit.
I certainly would not ignore that possibility. It's not as if it is a rare machine. You might actually find that parts from Chinese or Eastern European copies fit.
Possibly, yes. It certainly looks like a casting of some sort.
More of a 'worn away until the bearing ripped out', looking at the remains I think it may not be cast iron as it has torn rather than cracked.
Good idea...... Here you go:-
http:/isbd.net/yoke/p1020500.jpg
I don't have a TIG, only MIG and a little inverter stick welder.
Yes, ultimately grafting on to something else *might* be the way to go. It's one end of:-
spline-UJT-sliding spline-UJT-spline
Nope. Doesn?t work...
Tim
No fault, just worn away by long use.
Yes, this is one of the 'ends' where it couples on to the driven shaft, it's not a sliding joint. The sliding joint is in the middle between this UJT and another.
I've looked for parts for this before and found the needle rollers for the UJT but so far haven't found the yokes.
Oops, sorry, should be:-
What model is the tractor? Would a different yoke fit from another Kubota item fit? For instance I've seen yokes for rotary tillers that are internally splined, but where yours seems to have a hole (for a locking bolt?) they have a clamp.
I know nothing at all about these, just the result of a quick google.
SteveW
Thanks, that works for me!
OK so the needle roller bearing has been gone for a long time, that looks fairly irrecoverable. I'm not really familiar with Kubota tractors. UJ spares for their mowers look pretty expensive on eBay. This is obviously on a drive shaft, rather than steering. Less scope to bodge a drive shaft, I'd have said. If there are really no spares around then I still think I would be looking to adapt something from another mini-tractor. You might also look at ATVs.
Looks a bit like this, though
It's usually considered good practice to replace the spider and bearings a bit sooner :-)
Long time since I have had any Kubota tackle but George Browns at Leighton Buzzard were always helpful.
Ah. Yes that is well copulated.
hard thing to make - forged Id say. Maybe a blacsmisth could do it, but Id definitely say you need to get a new yoke that fits the UJ and somehow attach it to the splined bit
Maybe make a sleeve that fits over both and drill and pin it.
Having seen the photo it may be possible to modify a PTO yoke to replace it if the Kubota part is not available.
This site:
Shows some yokes with dimensions.
AJH
It hasn't been gone long, it is somewhat vulnerable because it's quite low down in front of the mower deck so does get hit by sticks and stones. In this case I was mowing, there was a bang, and I wasn't mowing.
They're expensive everywhere and seem to be subject to some sort of price fixing/control. Firstly US suppliers refuse to send overseas (even when they will send other stuff overseas) and US prices are much lower. Secondly if you look at a list of prices or quite varied small parts they are all the same (exorbitant) price within a few pence regardless of what they are. There are a few 'normally replaceable' items like filters which are cheaper but otherwise everything is $95 to $98.
Yes, it's the drive from the PTO to the mower deck.
Yes.
That's much longer and is the middle, sliding bit, my broken bit is on the other half of a much shorter one.
I've bought from them before, very reasonable prices for UJT needle bearings compared with just about everywhere else. However they don't seem to have anything small enough in the way of yokes. I'll bear in mind adapting something they have though.
T1600H with a 44" deck, the joint is part of the deck drive.
But I wondered whether one of the yokes might be the same
I suspect it's quite a lot bigger (in diameter as well) because it is (I think) a tractor prop shaft.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.