We have a bad bearing on one of our Alco S-2 engines. The babbit has worn through and it is running hot. Does anyone have a lead on a 7X14 usable bearing or a good source to have it rebabbited?

Thanks

Jimmy
North Alabama Railroad Museum.

Jimmy,

Know anyone heading for Southern Georgia? Talk to the guys at the Georgia Agricultural Museum in Tipton. They have one or two guys that do babbit for the machines they restore along with the 2' gauge Vulcan steamer they run.

https://www.abac.edu/museum

Rich C.

For the record, the bearings you looking for are plain bearings not friction bearings. Timkin's advertising campaign strikes again.

Robby Peartree

We can help you with rebabbitting (even if it is a diesel). SRC Mechanical Dept.

I'm well aware of the plain vs friction terminology however my experience has been that it is much easier to get someone to understand what you are asking if you say friction. If you say plain bearing you usually get the deer in the headlight look back. If you say friction bearing most will immediately know what you are talking about. So yes Timkin's advertising campaign was a huge success!

jb

Part of what preservationists should do is educate. While it is easier to tell the legendary story it is important for all of us to use technologically correct terms. After all bearings are used to reduce friction not create it. I used to fall into this trap until a mechanical engineer read me the riot act. Ignorance to technology does not mean it does not apply to us only that there is something to learn. If we do not educate about railroadings past including technology then what are we preserving?

Robby Peartree

Believe me I hear you, but I was talking to a retired RR worker this weekend whos RR career goes well back to the days when plain bearings were in use and he has changed his share of them out, but he had this blank stare on his face until I finally said the magic friction word :-)

jb

Wearing through the Babbitt and running on the brass is not uncommon or a problem. If you look at the attributes of Babbitt, most of them have to do with getting a new bearing to run on a shaft. I am aware of at least one property that ran brass without Babbitt.

If your loco has worn through the Babbitt and is running hot. I would be much more concerned about the condition of the journal. There are products that you can put on the journal to polish it up in service. Doug Debbs has, on this site, discussed them in the past. A hot journal could also be a lack of lubrication. Check you pads to besure the surface against the axle is clean, soft, and in good condition to wick oil to the journal.

Once a journal starts to fail it may be difficult to determine what failed first. It was a common practice to look at the journal at the other end of the axle and asses it condition to provide clues why the other journal failed.

It ran low on oil but I don't really want to talk about that right now :-)

jb

For the record, the bearings you looking for are plain bearings not friction bearings. Timkin's advertising campaign strikes again.

Robby Peartree[/quote]

Everytime some one calls them "Friction Bearings" you have to jump on them and try to push your term.

You are the first person I have run into in over 40 years around railroad equipment thet calls them "Plain Bearings"

Go find you an EMD #90 renual parts manualand go to page B1554 Page one and read the header.

EMD calls them "Friction Journal Bearings".

They were a party selling thwem.

Agree with Mr Johnson - I'm more concerned about the axle than the brass. Of course running without oil makes a big difference…… but you may need to polish the journal at the very least if you don't want to damage your nice new Babbit surface.

Friction bearings, Ha!

Some engineers with the Reading old cars would, if the station were level, make a full release just short of the stop. With conventional motor axle bearings and journal bearings, the train would smoothly come to a stop and stay put.

With roller bearing Silverliners, they needed to use the disc brakes all the way to the stop.

Friction bearings do have friction.

Phil Mulligan

Trains Magazine had a story about one of the Seaboard Coast Line companies during the 2nd Word War who had a few new boxcars with roller bearings. Someone high up in the Mechanical Department complained to the new green-as-grass college educated President that the rollers were no good, hand brakes had to be set to keep the cars from rolling away. He replied, "How much are we spending on scarce war fuel to make the other cars move?" Because of the special War Taxes on increased income, the extra cost of roller bearings was almost equal to the tax that would be owed if that expense wasn't incurred.

"Friction" or "Fiction"?

A plain journalled bearing can actually run smoother, quieter, and with less loss (friction) than a rolling element bearing. The key is choosing the correct oil viscosity and clearance for the given RPM and shaft load. See "Machinery's Handbook" The plain bearing will have significantly more static friction ("stiction") because at 0 RPM, the oil film does not develop pressure. As the bearing comes up to design speed, the oil film actually causes the shaft to levitate off the bearing surface.

But a railroad environment is one where RPM is far from constant, ambient temperature is subject to wide swings, and oil quality is difficult to control. So it is hardly shocking that the rolling element bearing has almost entirely displaced the plain bearing.

Let this mechanical engineer put in his two cents worth: in 30 years spent almost entirely designing large shafting systems I've used lots of bearings of both types. Among the engineers there was never any confusion as to the subject whether it was called a friction bearing, or a hydrostatic bearing, or a plain bearing, or a journal bearing. We all knew what any of those names meant, i.e., that there are no rollers, and there was no hard rule as to which term was the best to use.

And in passing, don't think that roller bearings are pure rollers, either, because many types of rolling-contact bearings have plenty of sliding friction, tapered rollers being one of the worst offenders. IMHO, what seals the deal for roller axle bearings on rail vehicles is that they have a secure environment maintained by effective and reliable seals; and because they are cartridge assemblies, the environment stays secure (usually) until they're swapped out. (In addition, the much smaller static friction, compared to plain bearings, saves lots of fuel.) In stark contrast is the plain axle box with a non-secure hinged lid and a simple, ill-fitting rear seal that often wears out and is difficult to replace. As a result, this very dirty environment is the cause of most failures, in my opinion.