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OT: Square bearing shaft fit

K

kb0thn

Stainless
Joined
May 15, 2008
Location
Winona, MN, USA
I have a skid steer trencher attachment whose front idler wheel came to me seized. Upon disassembly I was greeted with some chunks of bearing race and some balls and a pretty chewed up square shaft.

I ordered replacement bearings from the trencher manufacturer. They are NTN 5AS08-1, whose description is 1-1/8" square agricultural bearing. NTN shows the square to be 1.180".

Item # DC208TT5, Heavy Duty Disc Bearing - Square Bore, Cylindrical O.D., Type 5 On NTN Bearing Corp. of America

And the bearings I received appear to be something like that (it really looks like 1.185 on my calipers).

The shaft, in a non chewed up section, measures 1.13" square.

So what is the thought behind labeling a bearing 1-1/8", making it 1.18", and putting a 1.13" shaft in it? Seems wild to me.

Thanks,

-Jim
 
digger doug said:
It's ag...get over it.
Click to expand...

There still has to be some thought process behind it. It's a machined shaft, so it didn't come on a 1.13" square bar. And it mates with a perfectly fitting hole in a laser cut cover. I guess maybe their 1-1/8" square bar maxes out at 1.13" and that is what the cover is cut for and what I got for my shaft.
 
Not to worry. The inner race ain't gonna spin on the square shaft. A fairly close fit would be nice so the wheel doesn't wobble.
 
My Davis trencher has the same style bearing.

the 1 1/8" square shaft is/was hot rolled (you could still see the mill scale
on the sides all these years later)

So add your tolerance for Hot rolled, add in some rust clearance, and when you pull
it apart, expect much compressed dirt to come out.

But you still want it to come out......
 
digger doug said:
But you still want it to come out......
Click to expand...

Of course these folks kinda missed that point. Bearing from each side pressed against a shoulder in the middle of the wheel. No way to press the outer races out. Gotta torch them out.


Yep, my mind is blown. Different world than what my engineers design for shafts.
 
Illinoyance said:
Not to worry. The inner race ain't gonna spin on the square shaft. A fairly close fit would be nice so the wheel doesn't wobble.
Click to expand...

So given that it came from the factory with 0.05" of clearance. And now with the bumps and burrs and crap on that shaft it is actually a little tighter ... just run with the shaft that it is in and move on with life? It kind of bothers my OCD to re-assemble the thing with a beaver gnawed shaft...!
 
kb0thn said:
Of course these folks kinda missed that point. Bearing from each side pressed against a shoulder in the middle of the wheel. No way to press the outer races out. Gotta torch them out.


Yep, my mind is blown. Different world than what my engineers design for shafts.
Click to expand...
And what is wrong with torching out a bearing race ? It's shot anyways.
Not like there is sensitive copper winding nearby on a motor, just a high manganese dirt sprocket.
FWIW I like to "weld them out" these days, whenever possible.

If you try to "tighten up" the fit's for your Ag customers...they may drop you as a vendor.

Just Sayin'
 
kb0thn said:
It kind of bothers my OCD to re-assemble the thing with a beaver gnawed shaft...!
Click to expand...

It's made to spend its life working in dirt. Go ahead, tighten it up to a snug fit. Then see how long it lives and how much work it is to disassemble.
 
kb0thn said:
So given that it came from the factory with 0.05" of clearance. And now with the bumps and burrs and crap on that shaft it is actually a little tighter ... just run with the shaft that it is in and move on with life? It kind of bothers my OCD to re-assemble the thing with a beaver gnawed shaft...!
Click to expand...

No...make a new shaft from 1 1/8" Sq. Hot Rolled.
 
kb0thn - I know exactly what Doug means by ''It's Ag - get over it'' I had the same problems when I branched out in to that branch game.

The whole essence of Ag engineering fabbing and machining brought home to me, when having built a special purpose cultivator, and after a little tweaking got it how everybody wanted it, ………..I took it back to the shop for strip down and paint etc etc.

And upon delivery, Albert (the senior tractor driver - and a man I'd a lot of time for) looked it over and told me (genuinely) that I'd made a really nice job of it, adding ''all to be dragged through the dirt''
 
Limy Sami said:
kb0thn - I know exactly what Doug means by ''It's Ag - get over it'' I had the same problems when I branched out in to that branch game.

The whole essence of Ag engineering fabbing and machining brought home to me, when having built a special purpose cultivator, and after a little tweaking got it how everybody wanted it, ………..I took it back to the shop for strip down and paint etc etc.

And upon delivery, Albert (the senior tractor driver - and a man I'd a lot of time for) looked it over and told me (genuinely) that I'd made a really nice job of it, adding ''all to be dragged through the dirt''
Click to expand...

I used to work for a company that made the cutter bodies for blasting in mines. We held them to nice tight tolerances and held to with in a 32 finish or less. All so it could be blown to bits. I could only imagine all the work someone working at Raytheon goes through for the same end result.

At least they get goobermint money from it.
 
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