More on metal or plastic wheels

Wheels: Metal or Plastic II

In the on-going discussion of plastic wheels versus metal wheels, this exchange took place on the NMRA Modeling list. The abrasive cleaner mentioned in the text is the abrasive eraser block like Walther's Bright Boy or the Model Power Brite Boy. RTR is Ready to Run or Ready to Roll pre-assembled rolling stock.

LS said:
In a message on RTR you mentioned shifting from plastic to metal wheels. Why does it effect cleanliness? My plastic freight car wheels accumulate muck, which makes it hard for me to believe they cause the black stuff on the rails. We have had this discussion at several clubs in the West and some have stopped the "metal wheels only" policy.

Bruce replied:
There is yet much disagreement on the subject of plastic wheels, but here are the results of three extended tests I conducted, along with some theories about why we got the results we did:

The first experiment took place on a large HO public display layout that ran 10-12 hours/day, 7 days/week. The layout had several independent loops, all laid with nickel silver flex track of identical age. On most of them, trains of 6 to 10 cars with plastic wheels ran behind single 4-axle diesels. The need to clean track was constant, and abrasive cleaning was generally required.

As an experiment, one loop was equipped with all-metal wheels, and the track cleaned. The test ran four months before the metal-wheeled cars were dispersed. In that time, the only cleaning the track needed followed a scenery work session.

We had previously tried commercial electronic track cleaners on this layout (with plastic wheels), and found them not only ineffective, but also counterproductive -- cleaning was still needed, plus locomotive wheels pitted and required replacement sooner than normal.

A third experiment took place on a modest 4'x8' HO layout with brass sectional track located in an uninsulated garage. Operated by an enthusiastic modeler two or three nights/week, he found abrasive cleaning necessary almost every session.

Upon hearing my theory, the owner raided all three hobby shops in town for every Kadee wheelset they had, and re-equipped his entire fleet. It was six months before track needed cleaning again.

My theory on the reason plastic wheels cause such trouble is that being non-conductive, they tend to pick up a static charge. This charge attracts available dust and dirt particles which cake into the "gunk" we so often scrape off these wheels (and off the metal wheels operated on the same track). This "gunk" does flake off, and when locomotives pass over it, two arcs occur -- when the pickup wheels are lifted off the rail, and again when they drop back again. This pitting makes it easier for "gunk" to adhere to the rails, and is why regular cleaning seems by many to be necessary.

I know that there are those who adhere to different theories, and that various oils, cleaners, and patent nostrums are favored by many. My opinions are based on these experiments, along with forty years of anecdotal evidence, and I invite those with competing theories to tell us of their experiments.

Bruce Metcalf