Exposed needle-bearings on inside of axle boxes

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Benjamin Maggi
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Exposed needle-bearings on inside of axle boxes

Post by Benjamin Maggi » Fri Nov 27, 2020 3:21 pm

My steam locomotive has axles that run in needle-bearings that were installed in axle boxes machined from C12L14 steel. In the picture you can see that the inside surface of the axle box, as well as the inner surfaces of the needle bearings, are open and exposed. It is anticipated that I will be running the engine on coal, and ash (along with the regular operation of any type of live steam equipment outdoors) could give rise to dirt and grit finding its way into that gap and contaminating the bearings.

Should we be concerned with the bearing gaps and is there any way to close them up? We have discussed pipe cleaners stuffed around the edges. My engine has only two axles (it is an 0-4-0), and aside from two eccentrics driving a dual-water pump on the rear axle nothing is mounted on either axle.

Thanks.
IMG_0922.JPG
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gwrdriver
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Re: Exposed needle-bearings on inside of axle boxes

Post by gwrdriver » Fri Nov 27, 2020 3:47 pm

Yes, IMHO you should have some concern and right off the top of my head I can think of two ways of doing this. The most expedient way would be to make a set of split collars, recessed for O-rings cord, or even felt packing, which would form a back-seal against the axle box backs. Another way, which would require removing the drivers, would be to use shaft seals screwed or clipped to the backs of axle boxes. I'm sure there are other ways to do this.
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John Hasler
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Re: Exposed needle-bearings on inside of axle boxes

Post by John Hasler » Fri Nov 27, 2020 4:00 pm


Pontiacguy1
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Re: Exposed needle-bearings on inside of axle boxes

Post by Pontiacguy1 » Fri Nov 27, 2020 4:20 pm

Allen models locomotives use a large thin washer up against the axle box, with a retaining ring keeping it in place. they have no.other sealing, and they are not known to give trouble or wear out.

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LVRR2095
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Re: Exposed needle-bearings on inside of axle boxes

Post by LVRR2095 » Fri Nov 27, 2020 4:25 pm

I am curious about the choice of 12L14 for the axles. I would normally expect a needle bearing to require a hardened surface for the needles to bear upon. I remember the old Nelson Gray 1” scale trucks that used Torrington needle bearings and soft axles. The journals ended up being consumed rather quickly.

Keith

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Re: Exposed needle-bearings on inside of axle boxes

Post by Harold_V » Fri Nov 27, 2020 5:08 pm

I share Keith's concern. A hardened surface is generally desirable for any type of frictionless bearing, as there's a greatly reduced amount of surface area carrying the load, so it's easily indented (brinelled). I suspect that the axles will not enjoy a long life. Stressproof would have been a better choice, although even it may not perform as well as a hardened surface, and most likely would not.

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Re: Exposed needle-bearings on inside of axle boxes

Post by milwiron » Fri Nov 27, 2020 6:22 pm

Recessed split collars with felt inserts are an easy retro addition and the felt is easy to replace when it eventually wears. Pipe cleaners can make good bearing protectors and also oil cup filters but make sure the wire in the pipe cleaner can't get caught in your bearing.
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NP317
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Re: Exposed needle-bearings on inside of axle boxes

Post by NP317 » Fri Nov 27, 2020 8:18 pm

My reading of Benjamin's post is that the axle box was machined from 12L14 steel, not the shaft.
And a harder steel insert is between the box and the needle bearings.
RussN

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gwrdriver
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Re: Exposed needle-bearings on inside of axle boxes

Post by gwrdriver » Fri Nov 27, 2020 10:19 pm

For the NEXT time . . .

This is what I did on my almost identical axlebox situation.
First, I bought inner races which were over-long so that ultimately perhaps 1/8"-3/16" of the I.R. was exposed beyond the axlebox inboard faces, and I turned shoulders on the axles to match the I.Rs.

I bored a step in the axlebox I.D. to suit a metal cage oil/shaft seal to match the OD of the I.R.
The seal will now be essentially flush with the face of the axlebox and wear on the ground surface of the I.R. The little bit of extra length of the I.R. allows the seal to remain on a ground surface when there is lateral movement.

I suspect with care and lubrication (provided for) this arrangement will outlast me.

I thought I would have a much better photo(s) to illustrate things but no luck.
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JohnHudak
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Re: Exposed needle-bearings on inside of axle boxes

Post by JohnHudak » Sat Nov 28, 2020 8:41 am

Pontiacguy1 wrote:
Fri Nov 27, 2020 4:20 pm
Allen models locomotives use a large thin washer up against the axle box, with a retaining ring keeping it in place. they have no.other sealing, and they are not known to give trouble or wear out.
I've been looking at the Allen models method of the dirt shield with a snap ring, and I think I'm going to be using it on my PRR G5 axles.. The only problem I see, is being that the shield is pressed tight against the bearing and held tight with the snap ring, there isn't any side to side play available for the axle/wheel set other than what is built in to the axleboxes.. How much play should there be?
Thanks..

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Re: Exposed needle-bearings on inside of axle boxes

Post by RET » Sat Nov 28, 2020 9:29 am

Hi,

The following description is what I did on Dart.

An easy way to solve your problem is to modify the axle by drilling a hole in the end which meets with a cross hole where the bearing is. About 1/8" dia is OK. Next, you drill & tap for #8 or # 10 NC. thread and use a center drill to make a cone in the shaft end. After that, you take a cap screw with the matching thread and cut a 60 deg. taper on the head to match the cone on the center drill. Cut the screw to length so it fits in the hole you have made in the end of the axle.
IMGA0542-a.jpg
end of axle showing capscrew plug.
The above picture shows what I have described. In the picture, you will see that I've used a capscrew as a "Dutch Key" to hold the wheel on the axle. This is a simple method which allows the wheels to be removed whenever you need to. Not only that, but they go back in exactly the same position they were before. In the picture you can see a small roll pin. This isn't really necessary, the Dutch Key is quite enough.

Next, make a fitting as shown in the picture below.
IMGA0543-a.jpg
Grease fitting adapter.
To lubricate the bearing, remove the capscrew plug, screw in the fitting you made and with a grease gun, lubricate the bearing. The new grease forces out the old grease and takes any dirt with it. In the picture, you can also see that the crank pin has been treated the same way for lubrication.

Simple and effective.

By the way, if you need a hardened axle, use Thomson shafting. The outer surface is hardened to about Rockwell 60, but the center can be drilled and tapped. If you need to, you can machine the outer part of the shaft with carbide tooling.

Richard Trounce

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Re: Exposed needle-bearings on inside of axle boxes

Post by tetramachine » Sat Nov 28, 2020 11:47 am

I have two LE Pacifics. both have needle bearings running on HARDENED Races pressed onto the axle. One of the loco's Had worn out the bushings on each of the driving rods, the needle bearimgs were in fine shape except one which got rust from sitting a long time like 20 years. There are not seals on the journal boxes. On the second loco I drilled out the axles, and drilled holes in the races(carbide drill) so that grease injected into the axle center hole pushes out the old grease.

I am surprised that anyone would think that needle bearings run on bare axles .
My wheels don't slow me down

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