This was sent by e-mail by a member (Signalsam). He asked me to post it for him: --------------- I am kitbashing two N scale Minitrix Decapod 2-10-0 steamers into CNR Santa Fe type 2-10-2's. Both engines ran fine when I got them, but were dirty, so I took one apart to clean it. I put the first engine back together and it wouldn't run like before and kept jamming up in the gears. It had been quartered correctly and rolled smoothly with the motor out . I put the motor in and it jams up. I took the gears out and it ran smoothly down a slope with no jamming. I pulled the drivers out of the frame, put the gears and the motor back in and they ran fine. I removed the motor again, tested it and it ran fine. I put the drivers back in and it still jammed up. So I started looking very carefully at the second Decapod and did a very detailed examination to ensure that everything on the first Decapod was put back together like on the second Decapod. Quartering, rod assembly motor positioning etc. was all identical. I then (mistake ) took the second decapod apart VERY carefully to see if I had put the first one back together correctly and had done so! When I put the second engine back together, guess what? Now I have two Decapods that won't run. All of the four drive gears in the Decapod are straight cut, uni directional, and appear to be identical to each other. The screw drive is attached to the motor shaft and was not disturbed. I have 26 steam engines that I have taken apart and put back together and all had improved performance, including four Minitrix 4-6-2 Pacifics. What the problem with these Decapods, is absolutely beyond me. HELP.! Is there something about the assembly of this ten driver engine that is different than every other steam engine ever built? Some trick that I don't know about or something that I can't see? HELP! Signalsam.
Signalsam, get a jeweler's loupe, or high power magnification, and some Kleenex tissue. Carefully lay out ONE set of the gears in the order you remove them from the engine. Look for two things on each gear. There may be a hub extending out to provide clearence so the teeth will not drag on another adjacent gear, or the frame. There may not be a hub on the opposit side. You may have the gear turned around. The second thing will only be on one gear. Carefully wipe any grease off the face of the gear teeth with a Kleenex over your finger nail. Just lightly wipe down through each tooth. You may have to go all the way around. Study each tooth on both sides to see if there is sign of wear, or polishing, on any of the teeth, AT AN ANGLE, as would be caused by the worm gear in mesh. When you find that gear, you know it was the one that was supposed to have been in mesh with the worm. Now, look to see that this worm driven gear is installed so that when the worm rotates it presses against the polished surface on the gear WHEN THE LOCO RUNS FOREWARD! That's where the most wear comes from, not reverse. The hub should be on the side this gear is pushed toward by the rotation of the worm. That's what the hub is there for, so the teeth don't catch on the frame, or a gear tooth next to it. When you re-assenble, make sure you do not tighten the screw down too tight, it can flex the frame and jam the gear teeth together, causing a bind. If the gears are somewhat worn from age, some of the gears axel holes could be too big to allow proper radial mesh when torqued and will bind up, yet run free while coasting. Because these gears are plastic, you may have to drill out the hub hole, and make a bushing to press back in, to remove the excessive "play" which allows the missalignment. (I would just order a new set from Minitrix.) I no longer have a Jeweler's gear cutter, and hand filing is a B......ch! If that doesn't help, you may have to place it firmly in your right hand with your palm up, and heave it as far out in the ocean as you can, then spit after it. After thought: check for end play on the motor. It might "screw" the armature shaft foreward, or rearward and bind the worm on the frame or boiler, or something else. May not be a gear binding, it might be the assembly is out of alignment once the worm, or gears turn. Make sure all the wheel axel bearings are in and aligned parallel to the driven wheel. ------------------ Watash [This message has been edited by watash (edited 02 December 2000).]
