In todays Knoxville News-Sentinel travel section their is an article about the April 13 Great Smoky Mountains RR Dillsboro-Andrews photo special.It says the trip will be diesel powered and has a photo of GP 223. Is their a problem with 1702? If so when will it be in operation again? The trip is sponsored by Knoxville's Old Smoky Railway museum.

WINK638@aol.com

> In todays Knoxville News-Sentinel travel
> section their is an article about the April
> 13 Great Smoky Mountains RR
> Dillsboro-Andrews photo special.It says the
> trip will be diesel powered and has a photo
> of GP 223. Is their a problem with 1702? If
> so when will it be in operation again? The
> trip is sponsored by Knoxville's Old Smoky
> Railway museum.

I am not sure how much work they are doing to the 1702 but TVRM is going to do the wheel work on their machines in Chattanooga. I remember reading somewhere that one or more of the roller bearings they had installed on the drivers had failed as well but I am not sure of the details. As far as I know TVRM has not started on the wheels so the 1702 is not likely to be ready for the start of the season.

They are working on the 722 but I think it has a long way to go.

John Bohon

jhbohon@yahoo.com

This is NOT an official announcement but I can tell you that yes, the wheels are at TVRM. We have turned the tires. We are also to turn the crank pins but upon beginning this work, we found that most of them will be beyond the condemning limit after turning. This will require replacement of the crank pins. A plan is in the works between TVRM and GSMR to expedite this work and get the wheels back to Dillsboro as soon as possible.

I don't know for certain, but I believe all the roller bearings had to be replaced. And this would be after 3 years of service.

G. Mark

TVRM Shop Updates by Steve Freer
aw90h@cs.com

> I don't know for certain, but I believe all
> the roller bearings had to be replaced. And
> this would be after 3 years of service.

> G. Mark

If you could investigate that and report exactly what is happening to the group, I am sure that many would appreciate the information, considering the recent perception that roller bearings are a panacea for operating steam locomotives. On the face of it, crown brasses donÂ’t sound too bad after all.


Strasburg Rail Road
kelly@strasburgrailroad.com

I would also like to hear more about this. I know some USATC 2-8-0 operators in Europe were interested in the details of this conversion.

I heard through the grapevine that it was quite a job to fit roller bearings to this engine. The hard thing about retrofitting roller bearings to many locomotives is that the frame pedestal openings aren't large enough. My understanding is that the axles on this engine were turned slightly undersize to increase the available space for the roller bearing assemblies.

The two ways of dealing with this on new construction were to either provide larger frame openings (most engines) or use "floating driving axles" as on the N&W A class 2-6-6-4's. This effectively placed the roller bearing in the hub of each driver (and hence outside the frame openings), but required a driver cast specifically with this in mind. This fix would probably be too expensive for a modern day retrofit, but it is a neat solution.

Good Steaming,
Hugh Odom

> If you could investigate that and report
> exactly what is happening to the group, I am
> sure that many would appreciate the
> information, considering the recent
> perception that roller bearings are a
> panacea for operating steam locomotives. On
> the face of it, crown brasses donÂ’t sound
> too bad after all.


The Ultimate Steam Page
whodom@awod.com

Ditto what Kelly said. If this particular retrofit failed, it would be good to understand how and why.

Dave

Kelly -

We are also interested in what happened to the bearings. Once I have the complete story, I will pass it along. Let's don't draw any conclusions yet. I have not seen the replaced bearings either and a good post mortem on them will provide more answers.

Keep in mind that the GSMR has many very tight curves. I wonder if the rollers are seeing lateral loads that Timken didn't design them for?

More later on this developing story...

G. Mark

TVRM Shop Updates by Steve Freer
aw90h@cs.com

> Kelly -

> We are also interested in what happened to
> the bearings. Once I have the complete
> story, I will pass it along. Let's don't
> draw any conclusions yet. I have not seen
> the replaced bearings either and a good post
> mortem on them will provide more answers.

> Keep in mind that the GSMR has many very
> tight curves. I wonder if the rollers are
> seeing lateral loads that Timken didn't
> design them for?

> More later on this developing story...

> G. Mark

Hello G. Mark,

I work for a roller bearing manufacturer that produces bearing for the railway industry and I find it highly unlikely that Timken did not design these bearings to take the necessary lateral forces. The nature of the design of a tapered roller bearing cause most of the force to be taken by the raceway itself. The cone (inner race) back rib actually takes very little of the lateral load. Other more likely possibilities include improper loading of the cup (outer race) causing uneven load distribution across the raceway and roller, leading to fatigue spalling of the rolling components. Also, lubrication could be at fault. If there is any water vapor that gets onto the rolling components and causes water etch, spalling will also be a factor. If the mounted lateral clearance in the bearing stack is not to spec, this could also be the problem. Too tight or loose and the life of the bearing goes down dramatically. I am sure the Timken folks will figure it out for you. Hope this helps.

Paul A. Hubbard


hubbard5004@msn.com

I recently talked with Ryan Scott about this very issue and we will need him to fill in the exact details, but I don't believe all of them failed, however, given the difficulty installing them, I believe they decided to replace them all. I do know that one thought involves the wear mentioned earlier by Mark on the crankpins. Could the pounding have created further damage to the bearings? Perhaps Ryan can fill us in further.

When purchased these were also "off the shelf" designs with the thought that they would be easy to source in the future. As it turned out they were obsoleted parts soon after the installation.
One of the interesting things to me was the somewhat flawed logic in putting them in to the engine in the first place, it was supposed to reduce maintenance costs by installing something that is not easily serviced, especially in Dillsboro. I seriously doubt that 722 will receive this conversion! I think this goes for coaches as well in museum service on a museum line, what advantage do roller bearings serve? Especially given the removal and reinstallation charges when wheel work is performed.

David Farlow
Whitewater Valley RR

Hudson.Industries@att.net

My limited experience with them indicates that in general terms, the use of roller bearings substantially reduces running maintainence requirements and the frequency of necessary dropping of drivers for hub liner and crown bearing work, since there are no hub liners and crown brasses involved.

Locomotives built new with roller bearings that I have laid hands on used hollow cast tubes with boxes on both ends which ran between the side frames and fit into the pedestals on both sides. These hollow tubes had the bearings installed in the ends, and the axles rotated inside the tubes in an oil bath, in other words, an entire subassembly sealed against the elements and self lubricating - just topping off the oil sump now and again sufficed.

All lateral force was taken up within the races and transferred through these castings against the shoes and wedges. Shimming up the shoes and wedges isn't as large a job as rebuilding hub liners, and is also necessary on traditional driver boxes too, so no net loss there either.

They seem to have been well liked in modern steam practice as they were designed and built. The retrofit job done at GSMRR was simple and elegant but not like the original design - altering the axles and boxes and replacing the cellars with fabricated retainers and no oil bath or sealed system apart from the bearing seals themselves.

It is a shame it didn't withstand the test of time and use - it could have solved many problems. Haven't we all had to do massive rigging work on otherwise healthy locomotives to deal with a smoked crown brass because the cellar dropped or lost its waste, or to deal with a babbitt hub liner that cracked up and wiped out?

Thanks for giving it a good try to Greg Dodd and crew. We need every break we can get to keep these running economically.

Dave

I've heard a good report as to the conversion but I won't go into details because there is always some error in transmission.

To sum thing up roller bearings are a good thing. properly applied, installed and maintained they do cut costs in the long run. I hesitate to say short run because they are very expensive to convert.

Trivia: One power generation expert I know proudly states that all steam turbines use babbit bearings with high pressure lubrication because the vibration from the turbine vanes passing through the steam flow is more than roller bearing can handle. ANy comments?

pfdx@aol.com