Greetings:
Has anyone successfully used Nylatron for hubliners on steam locomotive lead trucks or driving wheels?
We used Nylatron for the lead truck hubliners on our No.3025. They are attached with brass screws to the lead truck axelboxes. There is a total of 1/8th inch lateral clearance and drip oil lubrication. The wheel hubs themselves are freshly polished and smooth.
The wheel hubs are running between 140~160 degrees F, while the axels run only a few degrees over ambient temperature, so I am fairly certain that our issue is with the hubliners.
I am wondering if the problem is that Nylatron doesn't absorb and dissipate heat like babbitt or bronze (which is what we have always used in the past). Or perhaps I am missing something else...
I would appreciate insight from anyone who has actually used Nylatron in this application on full size steam locomotives in daily service.
J.David

David - the only operator I know of that tried this (or something similar) was Stone Mountain Scenic RR - their approach was cut out a horseshoe shape on the bandsaw and jam it in - and given their track record with steam since about 1975 or so, I'd be relucatant to expect good, useful information from a real inquiry. I've used it in lining crosshead sides, seems to work OK on lightweight - 60 ton or less - full size in that application. I have been told it is hydroscopic and swells when wet by others, but don't know that from firsthand information.

dave

It (Nylatron) has been mentioned here a few times, here are three;

viewtopic.php?f=1&t=31134&p=156333&hilit=Nylatron#p156333

viewtopic.php?f=1&t=11623&p=53182&hilit=Nylatron#p53182

viewtopic.php?f=1&t=27730&p=127867&hilit=Nylatron#p127867

Hi David:

I assume you calculated the PV for the application and verified that the material will work for this application. If not, here is the link to Quadrant Plastics design guide:

http://www.tstar.com/pdf/quadrant-df.pdf

Hope this helps

Chris

David,

We are using a similar material on the lead truck hub liners on our SOU #401. They are attached to the box in such a way that all the retaining bolts for the liners are outside the hub face and the liners can be unbolted and slid out. Lubrication is with soft grease. We are seeing much the same results as you are with one twist. The left side hub runs a few degrees above ambient along with the journal bearing. The right side hub runs between 130F and 160F with the journal running about the same as the left side.

Obviously, we have an alignment problem causing the lead truck to favor the right side which seems to only happen when shoving the train. We are an out and back operation, pulling one direction and shoving the train back the other. We continue to chase that problem, which we think may be a buffer alignment issue, but in the mean time we are going to go back to bronze liners and see if they run any cooler. I will let you know how that works out. Like you, we suspect that this material is unable to transfer the heat and therefore all the heat that is generated is going into the wheel hub.

Russ

I'm not familiar with Nylatron specifically, but we did attempt a rod bearing out of one of the high density industrial plastics - don't remember which one. Unfortunately, we neglected to account for the difference in expansion properties of the new material. After only a few miles, the bearing got very warm as the gap closed up - I'm thinking almost 400 degrees if I remember correctly.

The good news was that no damage was done to the pin, so it was just a quick job to press out the plastic bushing and replace it with the standard brass one.

Eric

Russ wrote;

"Like you, we suspect that this material is unable to transfer the heat and therefore all the heat that is generated is going into the wheel hub."

Very likely correct. All materials have a property known as "thermal diffusivity" which combines thermal conductivity and thermal capacity. Thermal diffusivity is for all pratical purposes the "speed of heat" inside a material.

Plastics have "slow" speeds of heat, ferrous metals are better, aluminum is very good but copper and it's relatives (bronzes, brasses) have superior speeds of heat. That's why high performance computer systems use copper heatsinks on the microprocessor, the heat travels faster through the heatsink and is dissipated more quickly by the fan.

So the heat dissipation and surface toughness makes Bronze (as a generic family) an excellent choice for sliding or rotating bearings in a railroad environment

Plastic bearings are good for low load, inexpensive items (think consumer goods), or special applications in corrosive locations, etc. You can actually purchase ball bearing with glass balls running in plastic races, they won't take much of a load but you can run them right inside a very strong acid bath.

Diamond has a very high speed of heat and it is occasionally used in the mounting of high heat density devices like semiconductor laser diodes.

Cheers, Kevin

Perhaps it is expanding from the heat and closing the lateral motion gap too much. I would think bronze or babbit lined bronze along with lubrication would work better.
The idea of using it sounds good, but unless you tried it you'd never know.
I wouldn't attempt it on a mainline locomotive.
As to the 401 problem, I think you may be on the right track checking the radial buffer.

During the early 1980's Jack Anderson tried some nylon product on various wear points on our three truck Heisler. I can't verify if it was specifically Nylatron. During a winter rebuild, he cut pieces of it for use on various wearing surfaces.

Unfortunately, the experiment wasn't successful, it was fairly soft and deformed easily. I recall it didn't last long in service.

I know the 148 got them in 1974 or '75, but never heard how they worked out. Boiler issues sidelined her, with very little mileage on the overhauled running gear. I suspect the jury is still out on those hubliners.

I see pedestal liners on EMD Blomberg trucks that are made of some sort of engineering plastic. Is this Nylatron or some sort of derivitive?

EMD Blomberg pedestal liners are Nylatron.

DPK

As I mentioned in an earlier post to this thread we replaced the Nylatron hub liners in SOU 401 with bronze liners. We normally put 55-60 miles on the engine on an average operating weekend.

The last time we ran it with the Nylatron liners in place the right hub quickly warmed up to around 160F with the wheel center warming to near that throughout the day. The journal box remained at near ambient temperature.

We ran #401 this past weekend with the outdoor temperature at a balmy 98 degrees. With the bronze liner in place, the hub, liner, and journal box were all at about the same temperature, 126F with the wheel center warming to 116.

Our conclusion is that we will stick with either bronze or babbitt for hub liners.

Russ

Dredging up an old thread to add a bit more info to it for the reference archives regarding the use of Nylatron Hubliners. We've been running them at Greenfield Village on our two smaller locomotives for many years, but have recently made the decision to return to bronze as they need replacing.

Our D&LN Baldwin 4-4-0 is still running with the bronze liners that were installed on its driving boxes during its original service life. During its restoration to operation, the faces were cleaned up a slightly, but they were in good shape otherwise. A recent inspection has shown that they still look freshly machined after about 10 years in service now (our locomotives run about 33 miles/day, 7 days/week, generally at least 2 months out of each season if all three take turns in the boiler wash rotation, barring any mechanical issues that keep them in the shop).

As for the Nylatron hubliners on our small 4-4-0, the ones we just removed were installed only 6 years ago. They were badly chewed up, as were the steel wear plates bolted to the hubs. The steel was actually more badly eaten away than the Nylatron was. It seems as though once any cinders/grit introduced to the Nylatron embed themselves into the material, they just eat away at the steel hub regardless of frequent lubrication, which obviously defeats the purpose of the softer material.

Bronze might be more expensive at the start, but the damage done by Nylatron seems to negate the initial savings since it lasts half as long.