Bearing removal

[rhunt]

Before reworking your nice Proto separator, why not purchase a cheaper unit from Harror Freight or some other place and machine that tool. They go for about 40 bucks for a complete set. Bob

 

[dougtrr2]

I can稚 tell you what it痴 for, but it is an aircraft part. Problem is, I can稚 get a new bearing, but I need the bearing removed to mag particle inspect the shaft. We need to be able to inspect and reuse the bearing. The lead time to get a new certified bearing is almost a year.

I realize that aircraft parts have a whole different set of rules. But it seems odd that to replace the bearing it has to be certified. But, you can still reuse a bearing that you could quite possibly damage in the removal process. Is there any loophole that would allow you to use a non-certified bearing?

Doug in SW IA

 

[3Lfarms]

Cost of tools isn’t an issue. The customer will pay for it.

No loophole that I have ever seen to buy parts from an unapproved vendor that hasn’t gone through the procurement process to properly certify the part meets specification.

I am not happy that I have been asked (told) to do this by the muckety-mucks on high to get these planes in the air.

There is a contract with a vendor to build new units, but they wont deliver for another year. This is a stop-gap measure to “overhaul” these things as best I can.

 

[Ortimber]

Cost of tools isn’t an issue. The customer will pay for it.

No loophole that I have ever seen to buy parts from an unapproved vendor that hasn’t gone through the procurement process to properly certify the part meets specification.

I am not happy that I have been asked (told) to do this by the muckety-mucks on high to get these planes in the air.

There is a contract with a vendor to build new units, but they wont deliver for another year. This is a stop-gap measure to “overhaul” these things as best I can.

I own an aerospace certified machine shop, and you are correct, being able to purchase from a new supplier that is not on an approved vendor list is a no-no. However, if I was doing this repair, I would elevate the situation within my customers chain of command and let them know that destroying the bearing is almost a given and that there needs to be an alternative course of action.

 

[The Fred]

I have a full machine shop, so I think my plan today will be to make a bearing separator out of delrin so I don稚 damage the shaft.
In combination with heat/cold I think that gives me the best chance of getting the bearing to move a little so that a thin collet type puller can get behind the inner race and put it off.

You're doing A&P work and asking for help on a tractor forum? My motto here is if I can't fix it I'll smash it!

 

[3Lfarms]

You're doing A&P work and asking for help on a tractor forum? My motto here is if I can't fix it I'll smash it!

There are some pretty smart people here, and farmers get things done.

I have followed Big Barn’s shop thread from the beginning, and the depth of knowledge here is amazing and helpful.

 

[The Fred]

I'm joking.

 

[3Lfarms]

I own an aerospace certified machine shop, and you are correct, being able to purchase from a new supplier that is not on an approved vendor list is a no-no. However, if I was doing this repair, I would elevate the situation within my customers chain of command and let them know that destroying the bearing is almost a given and that there needs to be an alternative course of action.

So I did just that today, and was told to hold off. They will try to procure new bearings, which causes the engineers and procurement folks major headaches.
I have already modified a bearing separator to get behind the outer race of the bearing. They told me hold off just as I finished. grrrrrr

If they cant get me new bearings, I will put the whole thing, puller and all in the oven and warm it up and put a little tension on the puller/separator. The shaft is hollow under the splined area, so I will use liquid N2 to freeze the shaft and hopefully it will let go and move enough that I can make a set of collets that can get behind the inner race and pull it the rest of the way off.

 

[PILOON]

I own an aerospace certified machine shop, and you are correct, being able to purchase from a new supplier that is not on an approved vendor list is a no-no. However, if I was doing this repair, I would elevate the situation within my customers chain of command and let them know that destroying the bearing is almost a given and that there needs to be an alternative course of action.

I am (was) an AME and US A&P so perhaps a hint.

Canadian EO's (AC43) permitted usage of automotive common parts in AC PROVIDING they were 'new in the box'.

That was very useful for items like Magnetos, generators alternators etc that were often originally automotive in nature and adapted to Aviation.
Quality bearings should fit that category, (like Heim, Barden etc)

More than once I argued that point and usually got an OK.
My, documentation is out of date so things may have changed.

Most light AC engines use magnetos and most magnetos originally saw service in tractors
An example here is the points are exactly the same in many cases. (as other parts)

 

[hosspuller]

I have a problem I have thus far been unable to figure out and I知 wondering if one of you can give me an idea how I can remove this bearing without causing any damage to either the bearing or shaft.

View attachment 680591
View attachment 680592

I can稚 tell you what it痴 for, but it is an aircraft part. Problem is, I can稚 get a new bearing, but I need the bearing removed to mag particle inspect the shaft. We need to be able to inspect and reuse the bearing. The lead time to get a new certified bearing is almost a year.

The space between the bearing and splined area is so small a standard bearing separator can稚 fit between the bearing and splines.
I broke one bearing trying to hold it in a vice so I could press out the shaft.

The bearing is a press fit on the shaft and it took a about half a ton of pressure to get the inner race of the broken bearing off the shaft.

Is there a special tool that could help me?

Hydraulics... a blind cylinder to hold the gear, two half circles of shim stock to blank off the bearing race, lip seal to the outer race to the cylinder... then pump grease to the cylinder at the gear through a zerk. The grease will flow past the gear to the bearing. But the grease can't pass the bearing because of the shim stock. If the grease leaks past the half circles, then use multiple pieces to act like piston rings.

If you can move the bearing the width of the outer race, you can then use a knife edge to pull it off the shaft.

After some consideration, might not need the shim stock since the bearing is sealed and you'll have to restrain the shaft to separate the two.

Outer 1.25 diameter area minus ID .5 area = about 1.00 in sq.

1000 psi x 1.00 in sq = half ton pressure. grease gun should be able to develop 7,000 psi.

 

[fried1765]

So I did just that today, and was told to hold off. They will try to procure new bearings, which causes the engineers and procurement folks major headaches.
I have already modified a bearing separator to get behind the outer race of the bearing. They told me hold off just as I finished. grrrrrr

If they cant get me new bearings, I will put the whole thing, puller and all in the oven and warm it up and put a little tension on the puller/separator. The shaft is hollow under the splined area, so I will use liquid N2 to freeze the shaft and hopefully it will let go and move enough that I can make a set of collets that can get behind the inner race and pull it the rest of the way off.

My son knows the FAA administrator.
I'll ask my son to ask him to give you a call. :laughing:

 

[user.69169]

I suggest youthink of Nitrogen only as last resort yer life depends on. Temperature so cold it does nasty things to metal. Co2 pretty safe and usually sufficient to get shrink you need.

Oven idea is bad too- you said you got induction unit. It can concentrate heat on bearing where you need heat. Might provide enough heat to move bearing if whole assembly frozen in freezer. Heavy head end will retain lot of cold while you induction bearing.

Hollow shaft??? Hollow all the way thru or hollow part way? Might be better chill by shooting Co2 shaft.

 

[the old grind]

Agree strongly with all (removed) said above. I'd also leave N2 for expendable(?) parts, use CO2 if anything, and spray working from the long end if the hollow is blind.

I doubt that induction would heat the inner race enough w/o risking bad things happening to bearings and/or seals. See here from :25 or so. At :50 (pic below) see where the back of the separator has an area that could be flat ground a bit to sharpen the lips, & how blunt they are on that side. The tapered sides opposite might be touched up with a die grinder, polished, etc.

Two minute video here. Start at :25 or so. At 1:10 there should be something for the screw to push on & not bung up the end of the shaft.

How To Use A Bearing Separator - YouTube

Thanks to Supercheap Auto for this pic:

 

[denchen]

Its just an idea, and I`m no aero engineer, but what about putting a slim knife in a vice, blade up. Hold the gap between the bearing and the machined part on the sharp of the blade. Then take another knife, hold it over the opposite side gap, and gentle tap with a small hammer. If it opens a little, then thicker knives, until the feet of a puller will go in.