Ted S posted:I can't believe this thread came back to life after 3 years!
The Williams name has been around a long time, and I'm not sure what vintage of locomotive is being discussed in some of these posts. But I'll make a general statement (which is the same thing I've been saying for the last 20 years.) It's the gear ratio. It's always been the gear ratio. 98% of the O gauge locos made are geared too tall (fast) for an adult application: continuous operation at modest speeds on a home-sized layout with sharp curves. Going back to the first post in this thread, of course the "old timer" 4-6-0 runs cool, because its motor is operating in a healthy, sustainable RPM range.
Just about every vertically motored diesel ever made (there are a FEW exceptions) is geared too tall. (I'll also observe that the vertical orientation greatly limits the length of the motor AND the available "head room" for a flywheel.) Sure, speed control lets you run them at 5 mph or whatever. But especially if you're also pulling a load, there's a LOT of heat build-up. No easy way to change the gear ratio, and no easy way to remove the excess heat. Maybe real operating exhaust fans? Another gimmick and something else to fail!!
I can only guess that the manufacturers don't want to expend the effort to tame the noise, vibration, and harshness (NVH) issues which are more likely with high-rpm operation. But a properly geared drivetrain is a beautiful thing. Quality engineering design, good materials, and we would be running trains instead of discussing these problems.
A high gear ratio is not a panacea, I recently did command upgrades on a few Williams brass steamers with a 44:1 gear ratio. While slow speed performance is obviously great, by the time you get to around 45 scale MPH, the motor is screaming at over 8,000 RPM! Since most of the Mabuchi RS-5x5 motors top out near there, that's also the top speed. Some of those motors have much lower RPM max, and really are not at all suitable for the task.
