Oilite Bush Lubrication

[WearyParticipant @weary]

Application: Model locomotive carrying wheel axle-box.

Oilite bush dimensions: 12 x 15 x 25 (mm I.D. x O.D. x Length)

Note: The O.D. will be lathe machined by myself to this dimension to be a light push-fit into the axle-box

To replenish and maintain the oil saturation of an oillite bush as above would an oil passageway running through the axlebox to the middle of the outside (non-'bearing' surface) of the iolite bush be adequate/suitable, or should the bush itself be pieced through to the axle bearing surface?

If the oil passageway leads to the exterior, non-bearing surface what size hole would be appropriate? 2mm diameter, or larger?

Any pearls of wisdom/experience welcome as I have never used oilite bushes ……

Regards,

Phil

[WearyParticipant @weary]

What is the best way to maintain oil saturation?

[Michael GilliganParticipant @michaelgilligan61133]

Phil,

As I recently posted for Sam's benefit:

Here are more answers about Oilite than you even knew there were questions …

**LINK**

http://www.bowman.co.uk/products/oilite_technical

That said;

1. if you can manage to get a 'reservoir area' into the housing it will help greatly.
2. DO NOT drill through the Oilite bush. !!

MichaelG.

[HopperParticipant @hopper]

You might be able to do like Myford do on their countershafts and use two bushes with a small gap between them and an oil hole going into the gap. Thus oil gets around the full diamter then into the bushing frm there. In your case instead of one 25mm long bush, you might use two 12mm long bushes with a 1mm gap between them.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 26/01/2017 11:20:44:

You might be able to do like Myford do on their countershafts and use two bushes with a small gap between them and an oil hole going into the gap. Thus oil gets around the full diamter then into the bushing frm there. In your case instead of one 25mm long bush, you might use two 12mm long bushes with a 1mm gap between them.

.

+1

That's an ideal approach for several good technical reasons, as well as probably being more economical.

MichaelG.

.

P.S. … Phil: I should have mentioned that your proposed machining is NOT the preferred method … Please read the guidance before you decide how you're doing this.

It's rather buried in the Bowman site, so this direct link might be useful: 

http://www.bowman.co.uk/products/oilite_bearing_calculator?measure=metric&type=plain

[There is a companion one for flanged bearings.]

Choose an appropriate size for the bearing and then look at all three tabs.

Edited By Michael Gilligan on 26/01/2017 11:28:33

Edited By Michael Gilligan on 26/01/2017 11:41:34

[mechman48Participant @mechman48]

Having read the ref to Bowman brought back memories of how I used to fit Oilite bushes, in exactly the same way, got the oil hot, dunked the bushes into the oil & left overnight, well oiled by morning…

George

[WearyParticipant @weary]

Thank you for the links Mr Gilligan. Very useful indeed, and combined with Hopper's genius suggestion of two bushes with a gap between them I think that my oilite lubrication questions are resolved.

I was aware that machining iolite bushes is not considered a 'good idea', but unfortunately sometimes 'needs must'. However, on further consideration I may be able to resolve this issue too and avoid any necessity for machining of the bushes at all..

Thank you all very much for your speedy responses.

Phil.

[Ian S CParticipant @iansc]

If the worst comes, you can relubricate oilite bushes by filling it with oil, and pinching it between your thumb and forefinger until the oil oozes out through the metal of the bush. Useful for small bearings that you don't have time to bother doing anything fancy with.

Ian S C

[Martin KyteParticipant @martinkyte99762]

Or if you have a vacuum pump and a chamber you could do it properly.

Martin

[HopperParticipant @hopper]

Re machining Oilite, I can't see any harm in machining the OD if the bushing is to be pressed into a steel or cast iron surround? It seems the problem with machining is it "smears" the porous surface and keeps the oil from flowing through. Certainly a concern on the ID where the shaft rotates but I can't see the harm on the OD, if the oil is supplied to the inner part of the bush by the two bush method as used by Myford. Or am I missing something?

Around these remote parts, it is common practice, my local bearing supplier tells me, for machinists to buy bars of sintered bronze and machine up bushings from scratch, so the local shop does not have to carry a full range of bushings in all sizes etc. So it must work, perhaps not optimum, but I'm assured "everyone does it". (Just been through this with my ML7 countershaft bushings. Ended up ordering in the proper sized ones.)

Edited By Hopper on 27/01/2017 10:10:43

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Hopper on 27/01/2017 10:08:09:

Re machining Oilite, I can't see any harm in machining the OD if the bushing is to be pressed into a steel or cast iron surround?

.

I agree, Hopper … Perhaps I was a little 'sloppy' in my comment to Weary/Phil

What I was trying to point out was that machining to a 'light push-fit' is not preferred: The proper fit is a little heavier than that, and should compress the bush noticeably [hence the need for the assembly pin].

MichaelG.

[JasonBModerator @jasonb]

Though a light press fit may give more suitable clearances on the axle in this application, don't want things too close as the axle will bind up on every little bump in the track.

I have had no problem machining the OD of oilite with a CCGT tip

[Michael GilliganParticipant @michaelgilligan61133]

Posted by JasonB on 27/01/2017 12:26:59:

Though a light press fit may give more suitable clearances on the axle in this application …

.

Shouldn't that be a matter of making the axle an appropriate diameter ?

MichaelG.

[JasonBModerator @jasonb]

I think most people use off the shelf bar rather than turn down over the whole length at least on Locos

Different if machining the axle as youi would on a traction engine from a casting or fabrication much like this one I prepared earlier, will also have the double bearings the same as Hopper suggested.

[Michael GilliganParticipant @michaelgilligan61133]

O.K. Jason … [you did notice the smiley things, I hope]

I suppose the right approach might be to adjust the outside diameter of the bush to achieve the desired running clearance on the 'off the shelf' bar when inserted into the housing with Bowman's recommended press fit.

The one thing we really don't want to risk is the bush siezing to the axle and spinning in the housing.

MichaelG.

[Ian S CParticipant @iansc]

Also there is a risk of distorting the bearing unless it is mounted on a mandril for turning. Compared to a solid bronze bush, it's like turning a bit of cheese.

Ian S C

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