My favorite engine is the Marx #54 tin diesel lettered for Kansas City Southern. Unfortunately it has poor pulling power. Being a hollow tin body, it just doesn’t have much weight to it, making the marginal Marx motor even more marginal. Here’s what to do when a Marx engine can’t pull.
Why some Marx engines can’t pull
Marx’s cheaper engines were geared high, for speed, but they didn’t have much power. As long as they could pull the cars they came with and 1-2 extra, Marx called it good. Some of the tin diesels had a bigger problem, with only two powered drive wheels. They’re reliable, but won’t pull much.
Fortunately, many of the tin diesels have the better double-reduction motor, with the extra set of gears to slow it down and increase power. But even with the good motor in it, the tin diesels don’t have much power because they’re essentially an empty tin can. The whole engine, including the motor, only weighs about 1.2 pounds. Marx’s diecast steamers with the same motor in them pull much better, because they have more weight to give the motor the traction it needs.
What to do when a Marx engine can’t pull
Adding weight to toy locomotives is a common modification to increase power. Most of the modifications I see are permanent.
Fortunately, these Marx engines have tin-plated steel bodies. That means magnets stick to them happily. I bought a package of 40 disc magnets for $6. The only hard part is getting the magnets to go where you want once you have several of them in place.
And you can just as easily take the magnets back off, so it’s completely reversible. That’s important with the tin diesels, as they are rather uncommon and fairly valuable, as Marx goes.
My Marx 54 pulls pretty nicely with 40 magnets stuck to its underside. You want to stick them low, to keep the center of gravity low so it doesn’t get top heavy and tip over on curves. I stuck 40 magnets to mine and there probably would have been room for another 15 if I needed them. In my case, 40 was plenty. I wanted to be able to pull seven cars, and it will in this state. I didn’t have to take out the motor at all.
The magnets also likely exert some pull on the steel track below the engine. I don’t know how much, but it isn’t zero. If I tip the engine forward enough, it will pull itself the rest of the way and stick to the track.
With my magnets in place, an engine that would get stuck on my O34 loop with seven cars at 12 volts could pull them reliably at 9 volts without getting stuck, and run at a much more reasonable speed while doing so.
Sticking magnets to Marx rolling stock
The NMRA recommends a formula of 2 ounces plus a half ounce for each inch of length, so a 6-inch Marx car should, optimally, weigh about five ounces to reduce derailments and other tracking issues. A scale or plastic car should weigh about seven ounces. Needless to say, Marx rolling stock often comes up short in the weight department.
A 6-inch 4-wheel gondola weighs about 3.4 ounces. A 6-inch 8-wheel gondola weighs 4.6 ounces, much closer to the NMRA recommendations. No wonder the 8-wheel cars track so much better. An 8-wheel box car weighs more than five ounces already, so you can leave it alone.
Getting gondolas, hoppers, and other open cars to the optimal weight is easy. Just drop a few nuts, bolts, or washers in until the whole thing weighs what it should.
But on some cars that isn’t an option. In that case, stick magnets to their undersides. I think you’ll be happy with the ease of doing this, and how much better your cars will operate. My track isn’t the worst but it’s far from the best, and I notice far fewer derailments, uncouplings, and other issues when I follow NMRA weight recommendations.