# Rolling along....Improving OEM bearings



## Charles (Jan 2, 2008)

The latest from the TRS shops: bearing improvements and technology to improve the performance over the OEM parts. On our outshopped units, worn or out-of-spec factory bushings are replaced with either; high tolerance, high quality bronze bearings, or where space permits, ball bearings. The advantage to the ball bearings are; minimal maintenance, lowered rolling resistance and higher longevity. The ball bearings are, depending on the size, either greased and shielded, sealed, or open race type.

Source for bearings: www.vxb.com


The GS4 uses-


ID OD Width Type Qty


4mm x 7mm x 2.5mm shielded 6
6mm x 10mm x 2.5mm shielded 4

GS4 OEM bronze bearing top and new ball bearing installed in big end of the main rod:










Small end of the main rod improved bearings (made from standard bearing grade bronze):










AC-11/12's use:
ID OD Width Qty 
5mm x 8mm x 2mm open 8
4mm x 7mm x 2.5 shielded 12
5mm x 8mm x 2.5 Teflon 4

Cab forward OEM bearing (bottom) and new ball bearing (top) installed in the big end of the main rod:










A closer look at AC-11/12 upgrade to the main rod. *Note that there are 2 of the 5x8x2 open bearings in each main rod:

*










All of the rods require opening of the existing bearing holes, usually by 1-2mm. This can be done by the average machinist in a drill press or for complete accuracy; a mill can be used just as easily. The GS-4 side rods are counter bored to retain the OEM appearance on the outside, photos to follow. *

*


http://www.realsteamservices.com/shop-work/


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## Bruce (Jan 3, 2008)

That will be one smooth running engine when finished. Great information.


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## David Leech (Dec 9, 2008)

Hi Charles, 
Many thanks for passing along the source. 
I had always understood that ball bearings are okay as axle bearings, but a 'no no' on reciprocating parts. 
Do you feel that this is not an issue? 
All the best, 
David leech, Delta, Canada


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## East Broad Top (Dec 29, 2007)

David, I'm not sure whether what you heard is specific to small-scale live steam, but towards the end of the steam era, roller bearings on siderods were increasingly common. I know the N&W was a big fan of them. 

Later, 

K


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## Nick Jr (Jan 2, 2008)

I have a vague memory of a picture of three or four women pulling a very large steam locomotive with a rope. it was an advertisement for Timken and the locomotive was supposed to have bearings in all moving parts to show how easy it was to move it, power saved, used to pull more. I'm sure someone out there will know more about it than I have mentioned here, or even know where the pic can be seen. Nick Jr


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## Charles (Jan 2, 2008)

Posted By David Leech on 10 Jan 2010 08:27 PM 
Hi Charles, 
Many thanks for passing along the source. 
I had always understood that ball bearings are okay as axle bearings, but a 'no no' on reciprocating parts. 
Do you feel that this is not an issue? 
All the best, 
David leech, Delta, Canada 
Good day David
I do not believe so. 

Our thoughts are more to the point of improving performance and efficiency of the models we all enjoy. Function over fashion- "roll baby roll!". By choosing roller bearings for the moving parts of the engine, small power losses and simple lubrication are achieved. Relative to Kevin's input: N & W J 611 (the best modern Northern): The N&W engineers incorporated needle, roller, and tapered roller bearings throughout the locomotive to reduce friction and wear. 

Some other examples-

SF 2912: The main driving wheels are equipped with Timken Roller Bearings and the engine is also fitted with Timken lightweight roller bearing rods, and Timken lightweight Piston and Crossheads.
C & O Hudsons: Roller bearings on all axles and in the main and side rods. 
NYC J3: had roller bearings on their connecting and coupling rods as well.


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## rbednarik (Jan 2, 2008)

David, 

No adverse affect on out test sample from 3 years ago, as we had the rods off of it for a checkup this past fall. 


We were hoping for true needle/straight roller bearings, but there are none built to fit the dimensions of the rods, so ball bearings will suffice. These ball bearings are extremely resistant to pounding and lateral forces due to the tight tolerances, the number of bearing balls per race, and are rated for upwards of 10,000 rpm (some even up to 80,000!). 

The races are well machined and the thicknesses are more than adequate. The process is completely reversible, save for having to thicken the OD of the bronze bushing to put back in place of the ball/roller bearing. 

The only failures we have had (only 2 so far) were either caused by a fluke bearing (one time) or by not cleaning the bored hole and causing the shield to collapse into the race. The one time this went unchecked (both bad bearings were on one engine), the bearing had more drag than the others, but did not overheat or seize completely thanks to the high-temperature rating of the grease. Replacement was easy, press out the old bearing and press in the new with some bearing grade loctite (red loctite will suffice).


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## Chris Scott (Jan 2, 2008)

Ryan, 
Did you consider other types of bearings; ceramic, hybrid, self lubricating, PTFE, etc.? Or was the choice simply dictated by available size? 

Why are some of the bearings used, in the pictures, sealed and other open ? 

Thanks


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## rbednarik (Jan 2, 2008)

Chris, 

Bearing types are determined by the sizes. I am aiming for bearings that will be the closest fit to the OEM bronze. There has to be at least a 2mm difference in the ID and OD of the bearings, sometimes more, and this dictates which type of bearing (shielded, sealed, open, etc) is available. 

Then you also have to consider leaving enough material on the rods to be able to hold the bearings while retaining structural stability. For example, the small ends of the main rods were left with bronze (or brass) bearings due to lack of supporting material. Also, the small ends only rotate through about 30-45 degrees per drive revolution. These items, combined with the high thrust loads on the small end of the main rods ruled out fitting bearings to there, as high-tolerance bronze bearings are more than adequate. 


I choose to stay away from ceramic or hybrid bearings for three reasons; size, price and durability. The test sizes of ceramic/hybrid bearings that I acquired were not as resilient to pounding and other forces from reciprocation as the regular chrome steel or stainless steel bearings. 

The AC-11/12 main rods are the first to receive open (non shielded) bearings, all of the rest I have used are pre-greased; shielded(metal shields) or sealed bearings.


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## jfrank (Jan 2, 2008)

Excellent information Charles and Ryan. Thanks for posting all this. I want to try some of those next time I wear out one of my engines.


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## David Leech (Dec 9, 2008)

Ryan and Charles,
I was well aware about roller bearings on the 'real thing', but ball bearings would not have worked, and that is my concern about the models.
I worked for a while in an aircraft instrument repair shop, and the small ball bearings in instruments like Gyros just tore themselves to pieces under the stresses and strains.
Sealed bearings due the the seals will always seems stiff, as will shielded to an extent, but open will lead to all kinds of dirt to get in and mix with the grease which will cause problems.
Any idea how many hours you have on the first one so fitted?
I think that I will leave all my existing locos with their bronze type, but maybe on the next one that I build, I will seriously look at the ball bearings.
Mind you, there is no room for error in design.
Which bring me to another point.
Some of my old Aster rods, obviously had the bushes drilled AFTER assembly in some kind of jig equal to the axle centres, as the holes were not always in the middle.
Fitting ball bearings here would need a little bit of work to get it in the right place and probably need a similar jig, or good mathematics with a good slide table.
All the best,
David Leech, Delta, Canada


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## Charles (Jan 2, 2008)

Posted By David Leech on 11 Jan 2010 11:53 AM 
Ryan and Charles,
I was well aware about roller bearings on the 'real thing', but ball bearings would not have worked, and that is my concern about the models.
I worked for a while in an aircraft instrument repair shop, and the small ball bearings in instruments like Gyros just tore themselves to pieces under the stresses and strains.
Sealed bearings due the the seals will always seems stiff, as will shielded to an extent, but open will lead to all kinds of dirt to get in and mix with the grease which will cause problems.
Any idea how many hours you have on the first one so fitted?
I think that I will leave all my existing locos with their bronze type, but maybe on the next one that I build, I will seriously look at the ball bearings.
Mind you, there is no room for error in design.
Which bring me to another point.
Some of my old Aster rods, obviously had the bushes drilled AFTER assembly in some kind of jig equal to the axle centres, as the holes were not always in the middle.
Fitting ball bearings here would need a little bit of work to get it in the right place and probably need a similar jig, or good mathematics with a good slide table.
All the best,
David Leech, Delta, Canada


David
Since we are at most of the meets with this one particular retrofitted engine its running record is an example of how well the engine performs with modification. I can only estimate the number of hours on the GS4 over nearly 3 years of track time since the upgrades (approx. 100 hrs) in a variety of weather from cold/wet to hot and humid. The locomotive has been pulling a consist of heavyweights weighting about 150 pounds at many meets. The combination of that work load along with the high speed runs (150+ smph) have proven the bearings to be successful. 

As for as open bearing, I doubt there is much more a certain about dirt/material getting into the housing (no more a problem than open gears my WM Shay IMO) given most gauge one participants run on elevated off the ground tracks. In this case with that rod it is surrounded by the other elements of the running gear thus no directly exposed. 

BTW- this engine has run on tracks with ground level portions without having debris causing a problem with the bearings. Having run the GS4 over an extensive period of time under load, at max speed we feel confident in the setup.


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## Steve S. (Jan 2, 2008)

Hey Charles. Thanks for showing us these things that Ryan and you experiment with and then actually put to work. What do you think about the ceramic ball bearings shown at the suppliers web site? I always look forward to posts like this one.


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## Charles (Jan 2, 2008)

Steve
We enjoy the explorations into improvements on the many varied projects. As for ceramic bearings they seems to be quite expensive and none match the needs for the retrofits:


4x10x4 size for one is $60.00 vs. quantity of 10 for $20.00 of the size we used

Quantity in Basket: _None_ 
Part Number: *Kit7586*
Our Low Price: *$59.95*
Shipping Weight: *0.01* pounds


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## Steve S. (Jan 2, 2008)

*WOW !!*[/i] That is a huge difference in price. Now that I think about it,........ it just would not seem right having ceramic ball bearings in a metal loco anyway. After all, the real ones didn't have ceramic. Thanks again for the posts.


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