But WHY do plastic wheels collect more crud??

Some say the plastic wheels, being non-conductive, develop more low level static discharge and therefore attract the dirt. We've heard
people say that metal wheels cut down on crud a lot. Some of my RR has metal wheels but many cars do not because they are not really worth changing. The track gets dirty regardless of which type I use.
By running a track cleaner car frequently (and keeping the wheels clean), I haven't had MAJOR problems with plastic wheels. In fact, if you clean frequently (recommended), I can't tell for sure if plastic are dirtier than metals.
Larry 10feb05
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Pick up one car of each type and look at the wheels.
However, since you clean the track frequently, you might not see a difference. I changed to metal wheels a while ago, and the difference was very noticable. The sound of hte train improved as well as the rolling qualities of the cars.
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I totally agree with you Frank, those metal wheels make a really nice "clack-clack-a-clack" when they run over a diamond or frog. I used to get sooooooo much crap build up on plastic wheels that at times you almost couldn't see the flange.
John

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Frank A. Rosenbaum wrote:

ALL wheels pick up SOME dirt. My experience, too, has been that plastic wheels pick up MORE dirt. I don't know why this is so, but I doubt the idea that static has much to do with it.
To generate static by friction one normally needs friction between two (relatively) non conducting items (plastic, rubber, cloth, fur, etc.). The wheel is effectively grounded to the metal rail. Also, the dirt that builds up on a wheel usually has a substantial metal content (from worn track and metal wheels), and would likely be conductive enough to further ground the wheel. Static electricity has high voltage but usually next to NO current delivery capability ... even materials with very high resistance will effectively ground it. Even AIR grounds it, especially moist air.
I could see plastic axles turning in plastic sideframes as a possible source of static, but, if so, then our plastic trucks would be collecting lots of dust and 'growing hair'in addition to the wheels. I don't see this happening.
I think the wheels just roll up dirt off the track. This dirt is mostly just settled dust, with a little dropped oil, and worn metal and plastic dust from the track and the wheels themselves. There's just enough moisture or oily residue to cause it to stick together, and imbed into or adhere to the wheel tread. My guess is that the softer plastic wheels are more prone to microscopic imbedding. Despite the light weight of our model cars, the actual contact pressure at the point where the wheels touch the rail is considerable (very small contact patch). Each wheel acts like a miniature laminating press, and rolls it's own 'dirt tire'.
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If you want to find out if static is your problem try using some of that anti static spray to clean the wheels... it should be obvious when the dirt just falls off when you spray it...try monitor cleaner too...I believe that has antistatic stuff in it too!
And if you don't think static builds up without friction... static is the accumulation of excess electrons (or electron holes) and there has to be more than one way to do that.
Tom

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I think most cars have metal axles and plastic sideframes/wheels. Accurail has a plastic wheelset though, because it's all one molded piece (and they really roll bad too...they were the first reason I went to replacement wheelsets)
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me wrote:

But many, MANY people use Kadee or P2K wheelsets in Athearn (or similar) sideframes. That's plastic on plastic. It causes wear and friction problems over time, but I've NOT seen it produce static (though in principal it could).
A few otherwise decent kits come with all plastic trucks, and Life Like (not P1K or P2k), Bachmann, and several other low-end train set models use, or have used, all plastic trucks commonly.
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yeah, I noticed that, I use P2K's wheelsets too :) I'm don't know what kind of plastic they use, but they sure roll good.

Bachmann, Life like and low end train set models? I thought you said decent kits? ;^)
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me wrote:

Decent kits **AND* low end stuff.
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I'd suspect that the dirt embeds itself into the plastic easier than the metal wheels. Actually, I've seen times that metal wheels have collected dirt faster than plastic wheels do. It all depends upon the type of dirt that you are dealing with.
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Bob May wrote:

No doubt that's true. The type of dirt encountered is an 'environmental issue', and depends on the location.
What I get tends to be dust (mini fibers), grit (mineral?), oil, metallic dust, paint chips, and 'who knows what'. I suspect all manner of condensed vapors (paint, solvents, cleaning materials, outgassing plastics, etc.) also contribute. Particles of graphite from Kadee 'grease-em' shed from coupler pockets is likely also there.
We once used kerosene heaters in the building where our club layout is displayed at Christmas. It could get COLD 'back then' ... -10F degrees and 40 mph winds. WE were in a 'historic' building .. read: NO storm windows, NO insulation, free outside air flow beneath the floor. etc. FUN! Once we had FIVE such heaters going, and still had SNOW on the floor! The kerosene fumes condensed on the track something awful, like varnish. We had to clean the track about once an hour to get even barely acceptable operation.
If allowed to build up, the wheel 'gunk' rolls itself into 'tires' on the wheels. While a brittle material by nature, with care these can sometimes be chipped off in big curved segments. They often have a metallic sheen from the imbedded metal or graphite particles. I haven't tested it, but I suspect it's partially conductive (not enough to cause shorts, but maybe ground static).
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I lean to the idea that plastic wheels are somehow more porous to attract and hold the crud. I'm surprised no one has mentioned the difference in metal wheels. Old Athearn compressed metal powder Diesel wheels are notorious for attracting crud as compared with NWSL machined solid metal replacements. I think the same is true with Lionel wheels - the sintered metal powder wheels used on postwar rolling stock seem to collect more black adherent crud than prewar pressed steel sheet metal wheels or "new Lionel" cast zinc alloy wheels (although this could be related to the fact postwar Lionel ran so much better (reliably and thus longer) than the prewar trains or many of the "new Lionel" offerings. Gary Q

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Geezer wrote:

The sintered ("grindstone" texture) wheels as used on Athearn locos, give an unusually high factor of adhesion (traction), and wear well. Their affinity for dirt and poor electrical contact more than compensates for these virtues. They are, as you say, especially good at collecting dirt, and are indeed porous, which may well explain the phenomena.
Plastic wheels, on the other hand, are not particularly porous, yet they still collect dirt. It may be that the softer (compared to metal) plastic just allows dirt to imbed into it's surface more easily. Or, perhaps it gets (microscopically) scratched more easily, leaving pockets for the dirt to collect into. As I've stated, I don't think static has much to do with it, though it can't be ruled out entirely as a contributor.
And, as others have observed, it also depends on the nature of the 'dirt' in your layout room. Some even report more dirt on metal wheels, but that's sure NOT been my observation.
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Daniel A. Mitchell wrote: [...]

Acually, plastic is porous, at a microscopic level. This is why plastic cutting boards need regular dousing with bleach -- they provide good hiding places for kitchen bacteria, better than wood. Also, all plastics are "filled" with additional compounds to increase wearability, hardness, rigidity, etc. In effect, plastics are alloys. This means that at the surface there wil be different substances exposed to the crud on the rails, and some of these will simply pick it up easier. Some stuff just sticks more easily to other stuff, is all.
At any rate, that's how I explain it.
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Wolf Kirchmeir wrote:

True, but your description also applies to many metal wheels. Brass and Nickel-Silver are both alloys (mixtures of two or more materials), have a highly variable grain structure, and frequent microscopic voids. The sintered metal wheels are HIGHLY porous. Plating, too, can be very rough to start with, and frequently wears through, leaving an even rougher surface.
Since several different plastics are in common use in model railroading (Styrene, ABS, Polycarbonate, and Acetal, at least), and the quality of both the 'mix' and molding technique likely vary a lot, most anything is possible. Some plastics have low porosity, and make excellent moisture barriers. Others, like Nylon, are quite porous and actually soak up water like a sponge.
A smoothy TURNED fine-grained solid metal wheel is undoubtedly harder and less porous than many plastic wheels. I suspect this has a lot to do with their resistance to 'gunk' build up.
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I and others have also noticed the harder the metal wheel, the less dirt it attracts, hence my preference for stainless steel driving wheels.
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Terry Flynn wrote:

<snip>
Agreed. Plus they have a higher coefficient of friction than nickel-silver or brass (more T.E.), and wear longer. I've made a few such tires as replacements, and been very satisfied with the result. I wish more manufacturers would use SS loco (at least) tires.
The downside is that most stainless steels are hard to machine without proper technique, and don't machine easily on small non-rigid hobby-sized machines. It's do-able, but more care and technique must be used, compared to brass or NS. The 'trick' to working stainless is to use VERY sharp tools, and cut aggressively. You need to cut deep enough to get under the metal's hardened 'skin', and once you get a cut going, DON'T stop until you're finished. If you let the tool 'skate' on the metal surface, the SS will work harden, and it'll be VERY difficult to get the cut going again. The idea is to peel off the metal as fast as it work hardens, so the tool is always working on fresh metal. An adequately aggressive cut can be hard to maintain with 'flexible' and low powered machines. Such factors are not much of a issue with industrial grade machinery, though proper technique is still needed.
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On Wed, 16 Feb 2005 10:01:32 -0500, "Daniel A. Mitchell"

Who supplies driving wheels with stainless steel tyres? and at what price? All the claimed benefits are obtained with mild steel tyres which are readily available in a huge range of sizes and have been proven on thousands of locos. I have some in service which have been in use for over 35 years now and do everything mentioned above. Keith See <http://www.scalefour.org/ag/ag4.htm#Wheels or <http://www.sharmanwheels.com/
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wrote:

dirt it

I disagree with Mikes assessment about the coefficient of friction for stainless steel and oily nickel silver track. My measurements put it at about the same as nickel plated wheels, which is less than the softer materials. However I still can run full prototype length trains.

RTR brass models from Asia come with stainless steel wheels. It costs about double to machine stainless steel compared to brass. That's why manufacturers have generally avoided using it.

The only problem with mild steel is it rusts, and if rusty electrical pickup is poor. The fact is in my local environment, Sydney Australia, steel rusts quickly and would be a maintenance nightmare. Not a problem with stainless steel wheels, which I have been using for about 20 years without any rust. It's interesting that only some UK manufacturers make mild steel wheels, with Sharman wheels offering nickel silver tyres as the more expensive option. Nickel silver also does not rust, is good for pickup. It's my second choice for driving wheels, I have NWSL Nickel Silver wheels on some of my diesel locomotives, where the wheels are mostly hidden, and colour of the wheel tread is not as obvious. Much better than blackened brass or nickel plated brass which after some running wears back to dirt attracting brass.
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On Thu, 17 Feb 2005 13:43:54 +1100, "Terry Flynn"

ie they are not generally available.

Like I said, in 35 years this has never been a problem, including when I lived in Sydney.

Then you have another 15 years to go before they are shown to equal my mild steel ones.

The two suppliers with the biggest range use steel for most of their range, the other suppliers cater for those who believe the anti-steel views frequently expressed by those who have never actually tried it.

Can you support that? Nothing about such an option on their website and I have never been offered a choice when buying them. They do use nickel silver for their 3mm scale wheels which are done at the 3mm society request.

It oxidises which is pretty much the same thing!

Its my second choice to, still need the odd wheel that is not available in steel.

At least we seem to agree that brass is unsuitable for wheel tyres. Keith
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