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Grease Clearance

farmersamm

Cast Iron
Joined
Feb 26, 2008
Location
oklahoma
axle pin70.jpg
This is the front axle pivot pin for a 2wd tractor.
Pin diameter is 1.500
As it sits now, the bore ID is 1.504

The original assembly was a pin inside 2 bronze bushings, which were pressed into a pin boss. I have absolutely no idea what the original fit was. The bushings were gone, and the pin was a shambles. The new assembly consists of DOM built up, and turned to fit the axle tube hole, with a pin made of 1144 Stressproof.

My question is whether .004 is adequate clearance for grease to flow. The bore is 5" long, and the pin has a grease hole in the center of that length. I'm not sure how it will wear, being as it's steel on steel, but it is what it is(the pin is harder than the DOM, so I hope that will limit galling). It's entirely possible that the wear over a few seasons will push the clearance out another few thousands. Or more LOL.

I generally do make pins with this clearance, but they're in shorter bores, and don't get loaded like an axle pivot pin gets loaded.

Thanks in advance.
 
Most skid steers and tractors have a spec of 0.05" to 0.08" for grease pin points. so yes that is fine. most forget to put enough grease in there and it ends up being 0.125" sooner then later. but most will have hardened bushings to press fit into a bore with a groove in it to hold grease for a longer time then 2 seconds. Pins will be a Med carbon steel that is still soft or an alloy. DOM is soft, and 2 soft parts with lots of load and movement will be worn out quickly.
better question is who welded on that part?
 
I think when you weld it in the axel the DOM tube will shrink and the pin will be too tight.
I think you're probably right. I've been concerned about this too. It's been my experience that heat changes everything.
axle pin73.jpg
I sequenced the welding/machining on the pin assembly itself. One side padded, then turned to diameter using the unwelded side as the benchmark for indicating. Then the previously welded/machined side was used as the benchmark for the remaining side. You can see how much the heat affected the previously welded side. That's one heck of a heat signature.

axle pin53.jpg

Granted, there was mondo heat put into the piece while padding it, but it was all machined true to get rid of the effect of distortion. This won't be the case when it's welded in the axle. All bets are off.

In a similar situation in the past, I was able to keep distortion to a minimum by doing a large number of small tacks to hold the dimensions while the finish weld was placed over the top.

broken wheel224.JPG

But this was a fairly large piece, which made it more stable. I'm thinking, like you, that the smaller pin assembly will be more susceptible to distortion. I'm more of a welder than a machinist, so I'm always thinking of heat, and its effects. I guess I'll find out this morning
 
Seriously..... WHAT?

-Doozer
yep, I can get out the manual for a new holland, spec for hardened bushings is 5-8 thou. no real reason to need to machine within tenths.
5 thou is almost standard on most basic machined parts. just had a job that was 20 thou. tighter it is, more $$ it will cost for very little gain.
i fail to see what you said what?
 
yep, I can get out the manual for a new holland, spec for hardened bushings is 5-8 thou. no real reason to need to machine within tenths.
5 thou is almost standard on most basic machined parts. just had a job that was 20 thou. tighter it is, more $$ it will cost for very little gain.
i fail to see what you said what?

Take another look at your post... You were calling for .050" to .080" because you didn't put enough zeroes in your number.
 
View attachment 375754
This is the front axle pivot pin for a 2wd tractor.
Pin diameter is 1.500
As it sits now, the bore ID is 1.504

The original assembly was a pin inside 2 bronze bushings, which were pressed into a pin boss. I have absolutely no idea what the original fit was. The bushings were gone, and the pin was a shambles. The new assembly consists of DOM built up, and turned to fit the axle tube hole, with a pin made of 1144 Stressproof.

My question is whether .004 is adequate clearance for grease to flow. The bore is 5" long, and the pin has a grease hole in the center of that length. I'm not sure how it will wear, being as it's steel on steel, but it is what it is(the pin is harder than the DOM, so I hope that will limit galling). It's entirely possible that the wear over a few seasons will push the clearance out another few thousands. Or more LOL.

I generally do make pins with this clearance, but they're in shorter bores, and don't get loaded like an axle pivot pin gets loaded.

Thanks in advance.
 
I guess an update is in order, since there's still some responses.

I asked the question before the final weldout, and when all machine work was done. It was a legitimate question, although it should have been asked before I put the damn DOM in the chuck.

I guess, to make it all real. I Iike Machinery's. I go with what the pages outline. My clearances were not ISO, but what the old school(I hope I have that right) tolerances are. Slip fit, running fit, etc.

.004-005 is somewhere in some damn category.........can't remember which now. But, it was a compromise........given that the thing had to be assembled with less than an Epic effort.

On assembly, even unloaded, the grease was an effort. Literally having to lean on the gun with all my weight. NLG2 isn't 90w. And, nothing on a repair deal is totally 100% in line. And.......damnit...............004-005 is slightly thicker than a piece of copier paper. Plus, I don't have the capability to machine a spiral grease groove in a bore.

To get to a point where thousands mattered...........started here.


And, wound up here...............


That ain't too damn bad guys.

There's aspirational..........then there's real world. Not to step on toes, but it is what it is.

I said .060 on the axle stay..................I was generous axle pin118.jpg

This thing was a f'n mess.

I really appreciated the supportive comments. It tells me that some folks have been there, done it.

I tend to get a bit aggressive, and combative. This place makes ya that way, if you're not a job shop. I always tell folks to work from the machine out, never try to work to what the machine was, when it came off the line. You deal with the machine as it sits. It's not like working from a drawing, you have to work with a less-than-perfect lump of iron. And, for me at least...........it's with primitive tools. I like it, actually I thrive on it. It's the one thing about the business that I still have some interest in. I'm bordering on retirement..........one shove, one way, or the other, will determine how it goes. I'm tired of just making ends meet.

K'kins tells me that if I retire, I'll probably die in short order. I'd like to spend more years with her. Have to think it over. (She probably just wants to see me keel over in the pasture with a heart attack........she's a slave driver LOL) Just kidding. She's the love of my life. I hope she's the last thing I see.
 
I guess an update is in order, since there's still some responses.

I asked the question before the final weldout, and when all machine work was done. It was a legitimate question, although it should have been asked before I put the damn DOM in the chuck.

I guess, to make it all real. I Iike Machinery's. I go with what the pages outline. My clearances were not ISO, but what the old school(I hope I have that right) tolerances are. Slip fit, running fit, etc.

.004-005 is somewhere in some damn category.........can't remember which now. But, it was a compromise........given that the thing had to be assembled with less than an Epic effort.

On assembly, even unloaded, the grease was an effort. Literally having to lean on the gun with all my weight. NLG2 isn't 90w. And, nothing on a repair deal is totally 100% in line. And.......damnit...............004-005 is slightly thicker than a piece of copier paper. Plus, I don't have the capability to machine a spiral grease groove in a bore.

To get to a point where thousands mattered...........started here.


And, wound up here...............


That ain't too damn bad guys.

There's aspirational..........then there's real world. Not to step on toes, but it is what it is.

I said .060 on the axle stay..................I was generous View attachment 382347

This thing was a f'n mess.

I really appreciated the supportive comments. It tells me that some folks have been there, done it.

I tend to get a bit aggressive, and combative. This place makes ya that way, if you're not a job shop. I always tell folks to work from the machine out, never try to work to what the machine was, when it came off the line. You deal with the machine as it sits. It's not like working from a drawing, you have to work with a less-than-perfect lump of iron. And, for me at least...........it's with primitive tools. I like it, actually I thrive on it. It's the one thing about the business that I still have some interest in. I'm bordering on retirement..........one shove, one way, or the other, will determine how it goes. I'm tired of just making ends meet.

K'kins tells me that if I retire, I'll probably die in short order. I'd like to spend more years with her. Have to think it over. (She probably just wants to see me keel over in the pasture with a heart attack........she's a slave driver LOL) Just kidding. She's the love of my life. I hope she's the last thing I see.
Just be sure to jack it up so as to take all the load off the pin, if it is loaded you will get no grease where it needs to be.
 








 
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