Ztrains: Considering Quiet Locomotives

I'd like to preface this article by pointing out that noise levels are a very subjective topic. What may be a disproportionately noisy locomotive to one person may be a perfectly acceptable sounding locomotive to another. What follows is a look into the cause of a noisy locomotive, and one possible solution.

Are Z Scale Engines Too Noisy?
Many Marklin Z scale locomotives have a tendency to be disproportionately noisy while running. To some experienced Z scale users this is often simply accepted as a typical Z scale performance characteristic. To many however, this is often an unpleasant and continuing source of Z scale frustration.

I recently purchased several Marklin 4-6-2 Pacific locomotives, and had an interesting experience with them. Right out of the box, they all ran surprisingly quietly. After several days of extended running however, they all began to exhibit the disproportionate noise levels. They were all oiled properly and were broken in at low speeds. After they began to exhibit this extra noise, I had a look at the gear train, thinking there might be an answer there. Perhaps some sort of odd wear on the gears, or metal filings in the gear pan. The maximum clear magnification I have access to is a 4x lighted magnifying lamp, and through this I could not see any immediate cause for the relatively sudden appearance of this noise. Very frustrating.

To eliminate the motor as the possible source of this noise I have tested several 5 pole motors purchased new from an authorized Marklin dealer by running them for several days. I found the noise level of the motors themselves does not vary all that much from a brand new motor, to one which has been run for 20 - 30 hours. That leads me to think the problem is in the metal-to-metal contact of the gears. If I assume this, then something about the gears changes over the course of several days of extended running. The two possibilities that come to mind are, 1) the gears wear in such a way that they begin exhibit excessive noise, or 2) the gears ship from the factory with some additional coating on them other than the regular Marklin oil. Frankly I don't think possibility number 2 has any teeth (a little gear pun). That leaves me with some sort of fairly rapid, initial gear wear that would create noise.

Delrin Replacement Gears
If the noise issue is with the gears and their initial wear, then finding a way to render this gear wear irrelevant would seem to make sense. If the metal-to-metal contact of the gears were reduced, or eliminated altogether I believe this may well quiet down most, if not all, noisy Z scale locomotives. I've read about Delrin gears being used extensively in other scales, and how quietly their locomotives run. A complete set of Delrin gears may not be necessary to achieve quiet results though, perhaps only a few Delrin replacement gears placed between the existing metal gears would achieve similar results.

This illustration (above) shows the proposed Delrin (or similar material) replacement gears in red. As you can see, throughout the entire drive train, there would be absolutely no metal-to-metal contact of the gears. With only three replacement gears, one worm and two spur gears, all metal gears are now completely isolated from each other. This Delrin gear isolation may well dampen the sound enough to make every Marklin locomotive a quiet runner. Given the number of Marklin Z scale locomotives worldwide, there may be enough commercial potential in a solution such as this for an independent manufacturer to investigate further.

Does Sound Matter That Much?
To many users sound or noise can be a real issue. Marklin produces some truly amazing Z scale locomotives with performance and detailing that can rival that of the larger scales. In my view Z is a scale that draws the users, as well as the casual observers in for an intimate look, more so that any other size model railroad. Maintaining this wonderful, miniature re-creation extends beyond the visual, sound can and should play an important role.

Addendum
Since I first wrote this article, I have been in touch with a gear manufacturer who also happens to be an HO scale enthusiast. I have had a few conversations with him and hope to have a meeting with him in the near future. He has been manufacturing Delrin gears for years, and having seen the size of the gears I'm dealing with he thinks some Delrin prototype gears may be possible. I'll update with a new article if I can get these gears produced.

August 18, 2008

NTS 2008 Video: Steve Gibbs

Steve Gibbs has edited and published a 9 minute video from the recent 2008 National Train Show in Anaheim, California and it nicely highlights what's cooking these days in Z scale.

Sit back, relax and enjoy this look into Z scale at a major train show.

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