Dear fellow N scalers: I am stumped with an issue on my old Arnold Pacific. I recently picked it up in used condition. The problem is that it performs half as well in forward as it does in reverse. In reverse it runs like the powerful beast I expected. In forward it runs pretty smoothly but lacks that speed and power. It is lubed, I re-tendered it, flipped the motor, ran it fast, and ran it slow. I can't figure it out. If anyone has an idea what this is caused by, I'd love to hear it. Thanks, RICK
I was thinking that the front truck in these caused problems hanging and inducing additional friction. I can see where backing (pulling) the front truck would prevent the truck pivot from binding. That would be the first place that I looked. You should note that the brand new Kato GS's are experiencing front end problems (not to mention DCC shorting).
Sometimes the #2 and #3 drivers are out of quarter with each other causing binding in the side rods. In reverse there is enough play in the gears that the pressure is relived and it runs easier. If the counter weights on the drivers don't appear to be in "phase" with each other you can remove the cover plate on the bottom and lift the #3 driver up to slip it one gear tooth in the correct direction to bring the drivers into line.
I was aware only of derailment problems. Is there something else I should know? Removing the spring in the pilot truck assembly seems to have solved the derailment problem in my GS-4. I am trying to decide on sending mine to one of the professional installers for a wired decoder installation. If there are other problems I have not heard about it might affect my decision. Thanks, Ben
This is not unusual in my experience with some older steamers. My Minitrix 4-6-2s certainly ran better in reverse, no matter how much fiddling I did, nor how long I ran them on a break-in loop in forward. My theory is that some engines are simply better balanced in reverse. The rear drivers are usually closer to the motor. The rotational torque of the motor is transfered to the frame, which presses down on the rear drivers in reverse. In forward, that torque pushes down on the front drivers, which are much further away, while it lifts the rear drivers. Going in reverse does lift the front drivers, but they are further away. So, when in reverse, the rear drivers get a lot of downward push, while the front drivers get just a little lift. In forward, the rear drivers get a lot of lift, while the front drivers get only a little of downward push. Most likely, however, it is caused by the way the gears are cut. A worm/worm gear combo usually works better in one direction than the other. It's not too noticeable on my Life-like 2-8-8-2s, but I suspect by observation that it's there. They seem to running slightly better in reverse--but just slightly. If I was fanatical about it, I might try pulling the worm off the motor shaft, flipping it around, and then flip the wiring. But, due to the small diameter of this Minitrix motor shaft, pulling the worm is hard. Another theory of mine involves the eccentric crank, especially on the Minitrix 4-6-2s. It seems to have a smoother path in reverse than in forward. It's pulled around in reverse without acute angles coming much into play. It's pushed around in forward, and seems to cause a sticking point when it's at an acute angle to the siderod. This has more to do with where the rod is mounted than anything else, I think. I've observed that the Minitrix 4-6-2 in forward will "stick" at the same point every time while, in reverse, it does not stick at that spot.
Thanks to all that replied. I don't think the front pilot wheels are a problem. They are free rolling. The driver adjustment may be something to look at. I'll check it out. Pete, I suspected something like the worm gear. I thought of adjusting the position on the shaft but not flipping it. How would you suggest doing that? RICK
