Eight hours of running time (backwards and forwards) didn't seem to have much (if any) affect on mine, nor did adding lubrication. So, I instead tried loosening up the chassis screws a turn and, lo, that did seem to alleviate much of the binding. I still can't figure out what's causing the bucking though, so whatever that is remains beyond my skills to analyze and fix. Apparently this particular model is just a QC lemon (and one that any normal person would've simply returned for replacement). Fortunately, my other one runs flawlessly, so I'm not ready to damn the whole barrel based on the one bad apple (to mix fruit metaphors). -Mark
BTW John, here are a few spare blank lines I had laying around. Feel free to use them next time Cheers, -Mark
I'm trying to conserve the Trainboard gigglebites. Comes from being a crochety old geezer who grew up in a log cabin.
Chris: I recall you mentioned this thing on the Nn3 list as a possibility for narrow-gauging. What do you think now of the possibility? Also-how difficult was it to pull the driver centers? (don't have one yet myself...)
Thanks for posting that shot of the gear drive with the plate off. I thought it was geared AND with rods, the shot clearly shows that the only thing powering the rear drivers is the rods. So, at least in my book.... that could suggest that the drivers are out of quarter to get that kind of bucking. If the rods are litterally flopping around for the ride (sorta like Rivarossi) they can't make anything buck. If they are responsible for propulsion, they have to be pretty good and the tolerances are tight. And, the larger the driver the bigger a quartering problem is. They don't have to all be precisely 90 degrees, but they all have to precisely agree on the offset. To prove it, but I can't see it easily - any way to pull the worm out of the system so that the chassis freewheels? Because if you can usually feel the binding with your fingers and analyze it a lot easier than trying to watch the gears do it. I'm not a big fan of requartering drivers, I've done it, but I had to make a custom-made jig to do it on the Atlas 2-6-0 I mucked up, also a Micro-ace product dependent on rods for propulsion. I 'thought' I could swap the traction tire wheels to the center on my 0-6-4 and all I made was a terrible mess that it took me weeks to straighten out. I seriously messed up the driver quartering on that one and had t fix it. But if they are just a bit variable on that driver quartering, that would explain a lot of the inexplicable differences posted so far.
How exact does quartering have to be? That was one of the first things I checked, and just eyeballing them they looked OK to me. Or least as OK as any other loco I've ever checked (12:00 and 12:15 or whatever). -Mark
For my 2 cents worth I just looked at thier parts schematic and it certainly appears from that only one driver axle is geared. So Randgust may be onto something here.
Definitely only one geared axle - see my picture a couple of pages back. But if mine is out of quarter, it's not so out of quarter as to be detectable by my eyeballs. To be honest, even my good one has a small amount of buck to it - just not as much as my "bad" one. But really, we're talking fairly miniscule differences in performance here. Maybe an "A" rating versus a "B+" rating. Of course, that's after a lot of tweaking on the "bad" one (which was more like a "C" out of the box). IIRC, Atlas has recently moved production to a new factory so the occasional "less than optimal" 4-4-0 might simply be due to "growing pain" type QC issues (issues that Atlas will presumably address in future runs). -Mark
Has anyone checked the traction tires? Could be a slight imperfection in thickness that might be a cause of the bucking. And do my old eyes see bearing blocks in the parts schematic?
Sorry Mark, I didn't catch that earlier. I was posting out of frustration. I doubt the painted ones are any less fragile but at least you don't have to take them apart to paint them. I expect an undecorated loco to be aimed at a painter and it should be able to be disassembled and paintable. With all the details glued/stuck on, it is useless for anybody except those that want a two town gray loco with a black tender.
I really have no idea about making it Nn3, but other have converted the Bachmann loco so I imagine it can be done. 3 of my driver centers popped right out (they are glued in) I'll work on the last driver once I have replacements in hand.
Thanks Chris. Thinking about pulling the centers to re-work those spokes... Looking back at Marks photos of the mech, I've some doubt about NG-ing it. I converted the B'Mann mechs years ago, and it isn't built anything like this one.
I'm pretty sure the Bachmann one is geared with the rods flopping along for the ride..... Anyway, on the quartering. The tighter the tolerances between the crankpins and the rod holes, and the larger the driver, the worse this can get. I learned 'Quartering 101' in HO scale when I bought a kit Mantua 4-6-2 as a kid. Man alive, did that have problems. And I pretty much made them worse, but I learned. So the answer to the question is that the quartering has to be at least as precise as the maximum amount of 'slop' in the rod/crankpin relations. When I have the worm out, and I can roll the mechanism down the track feeling for resistance, when it binds up, I feel the rods with tweezers, seeing where it is loose and where it is tight. Then you have to figure out 'which way' you need to go with at least one set of wheels - on which side - in, or out. You can guess it, which can be really frustrating, or you can make a styrene jig to hold the drivers and check them against each other; point being that they don't have to be precise 90-degrees, but they do have to agree with each other within the rod hole tolerances. I'll have to photograph the jig I made, really it's just a measurement tool to try to figure out which set is 'off' compared to the others. It worked, anyway. Remember what happens when it binds up, it's then going to try to skew the driver sideways in the frame until that binds as well. With a 4-4-0 and no valve gear, about the only thing left here to go wrong is quartering when you think about it. I mean its POSSIBLE that the rods aren't exactly the same length, I suppose.... would have the same impact as being out of quarter. The Atlas 2-6-0 is also MicroAce, the design/manufacturing technique on the 4-4-0 looks identical; it's an improved 2-6-0 (both sets of tender wheels pick up on this one instead of just the rear truck on the 2-6-0). EDIT: I checked the parts diagram, there's driver backs, a separate axle, a separate center gear, another half axle, a driver back. So there are four points of alignment per wheelset. I think out of quarter is a very real possibility here, want to study mine too because although it doesn't bind, the lead driver has somewhat of an elliptical movement that I thought was 'out of square' (angled slightly) rather than out of quarter. Man, though, there's enough parts in the running gear though including spacer washers between the main rod and the siderod. It's related to the problem on the Shay, too.... there's only so much slop in the false gear train on the side of the Shay, and if you pop a truck off and put it back on just ONE TOOTH off where it started from, you've got a mess on your hands because there's now stress through that drive train that wasn't there before.
Correct. The B'Mann has 4 gears- a gear on each axle, and a drive shaft with 2 worms working directly on them...
John, Just so you know, a blank line takes up one character, a carriage return. In an average post, you may save 4-5 bytes by not using new lines, about 1/100th of a percent of the data displayed on the page.
Well, I took one of my two undecorated units out of its box only to have the pilot fall off onto the table. Remembering Mark's warning about fragile details I carefully turned it over and using my reading glasses and magnifying glass I managed to see how the pilot went back on. It took a little doing, but I got the pilot back on and then I readjusted the unit in my fingers and realized I just pinned the handrail to the side of the boiler. Thankfully I didn't snap the stanchion all the way off, I only cracked it. I put a drop of ACC on the tip of an Exacto knife, and again using my glasses and magnifying glass let it run into the crack and then gently edged the whole thing back in place. It seems to be steady, but who knows. Of course, while I was doing this I folded the whistle over. So I repeated the procedure on the whistle. I am not sure how long it will take before I manage to knock everything off. Yikes.
Just a note if you have to work on one of these. The steam and sand dome tops pop right off. If you remove it less chance of breaking off the whistle. I'm gonna try to drill my whistle out and core it with music wire.
The pilot should have been held in place by a screw between the cylinders and I am not sure what else that screw holds in place. But if it is missing it should probably go back to Atlas. If it isn't it sounds like somebody may have tightened the screw too much and it went through the hole in the pilot which would mean that hole is now too large which would be another Atlas issue.
I am monitoring all of these comments and will send a link to the topic back to the factory once it reopens after the Lunar New Year.
Well, I really analyzed mine last night. What 'looks like' an out-of-round movement on the lead axle was actually a lump in the traction tire that wasn't all the way in the slot. A little tweezer work fixed that. Checked my quartering carefully, mine is certainly OK, I don't see any odd binds at all. Under full slip and creep there's nothing to report. I think it could happen, but I don't have it. Pilot is OK, yeah, everthing on the PRR one I got is basically good. I'm tinkering though to see if I want to put weight in the cab to get a little better pickup on that rear driver, and also a little more weight on the tender (coal pile or wood pile) same thing. At this point I'm just putting weights on an testing, but it does look like a little on the tender and a little more in the cab is a very good thing. I'm running it through a C80 #6 insulated frog crossover now without any hesitation, my ultimate pickup test.
