Check out the photo below. This is a Proto2000 C&O Mountain (HO Scale) I've had since about 2003 or 4. Last spring I had TCS WOW Sound decoder put in and it has run great. About a week before Christmas it was running fine and just stopped. No motion, movement, etc. I put it aside until today. I started looking at it and noticed the drivers. The 2 center drivers on the left side are jacked up off the rail. The right side appears fine and sits on the track as normal. Anyone seen anything like this? While I will take apart a diesel in a second, I have always been hesitant to disassemble steam engines, especially putzin' around with drive rods. Any thoughts?
It's the driver, all right--the loose nut behind the wheel. Wait, that loose nut doesn't have a wheel. This happens as they age, and motion causes the holes in the rods to enlarge. Rotate the rear axle forward (counterclockwise, from that angle) a bit and you'll be off and running again. Or, if the rear axle is the geared axle, rotate the rest backwards (clockwise, from that angle). But it'll be a recurring problem. If you can find the perfect sleeve for the screws which hold the rods to the drivers, big enough inside to fit snugly on the shank of the screw, small enough to fit in the hole in the rod, and narrow enough to prevent the rods from wobbling back and forth, you'll be in hogger heaven.
I see something odd about the connecting rods between the drivers. Why are they diagonal? I took a quick look at my BLI Mikado and they're dead straight horizontal. But looking at your engine, I noticed that the front driver connecting rod pin is in the lower front quadrant, while the rear driver's pin is in the upper front quadrant. That's just plain hinky. I'd check that out before anything else.
I would disassemble the model and requarter the drivers. Proto 2000 models are known for plastic axle gear cracking problems on their diesels, and I suspect a similar thing has happened here. If the axle cracks, the two wheels loosen and can rotate relative to each other, putting them out of quarter. If the model has sprung drivers, lifting axles are not out of the question, especially if the valve gear is bound up.
Understood. I have a numerous Proto2000 diesels and every one I have replaced the axle gear with the A-Line replacements. Appreciate all the responses, now I'll have to digest them and figure out how to adjust the rods, etc. This will be good for me as I usually hide under the bed when I have to deal w/ steam driver/rod assemblies.
I was thinking of the cracked axle thing. That would loosen the axles and definitely put the wheels out of phase, and might even lock up the mechanism (I've experienced that with their diesels at low speeds. I even had that with a Bachmann GE 70 tonner). If there's a way to open up the bottom, under the driving axles, and inspect those gears. It's insane that there's so much effort at P2K into quality details, motors, a heavy frame, etc. and leave out an easily fixed issue inside the trucks...
Is this another instance of "genius" engineers stuffing a metal stub into plastic gears/axles ala Bachmann N scale? No excuse for doing such a stupid thing. Doug
The rods should always be level so deffinately something askew, is it locked up? clearly the wheels have gone out of quarter but was that caused by a part of the linkage (rods and valvegear) interfering and spinning the wheels out of quarter or a component failure sending the quartering out and then locking up due to the lack of quartering... You say the wheels on the opposite side are all still touching the rail but is the side rod horizontal? I for many years was scared to tackle taking a steam loco apart due to horror stories over valvegear etc. A failed loco, like in your instance, was the impetus I needed to tackle my fears and the loco. At the end of the day, how worse could it be? the loco doesn't work, so if it doesn't work after you poked around you are no worse off right? treat it as a learning experience. I found articles, blogs and slides done by others about servicing and repairing brass locos and that explained a lot about how things work in layers. I it not a brass model but the real things work the same and all models replicate that. Oh and if you take screws etc out or shims etc, my top tip is to lay them all out flat like a flat plan in the orientation you take them from the loco. Good luck, i'm sure you'll improve for it. Make sure you let us know how you get on.
Wanted to circle back on this. I parked this engine in the back of my staging yard and put off dealing with it. This AM I watched a short video on "quartering" and got a full understanding of what that is. I went into the layout room and grabbed the engine. Where the rods where binding it seemed logical if I could rotate the rear-most driver down, it would quarter (align) as well as relieve the binding. I noted where the new position would be and flipped the engine over. Sure enough, those crankpins were in line and if my "adjustment" were successful, it would indeed be a "quarter turn" apart. So I gently (but firmly) pushed down on the rear driver crankpin and felt a pop. The pin aligned with the others, the rods stopped binding, and everything was aligned a quarter-turn from the other side. BINGO. Got my engine back. Engine runs like a champ. This afternoon I'll lightly oil the drive rod connections and clean the wheels with contact cleaner. Good stuff. THANKS!!!!
Anyone know why real locomotive driver rods are quartered and not 180 degrees apart? I know. Just seeing if others know. No fair peeking in google. Doug
It's mostly because of how the valves and cylinders work in relation to the drivers. When they're "out of quarter", meaning that one or more wheels are off the 90 degree difference, the least that can happen is some slippage every time around as the out of quarter wheel is forced to catch up. That makes the loco shake like nobody's business. Then there's the big problem when the two sets of driving wheels on each side of the engine are 180 degrees apart - it the engine stops when the wheels are arranged so that the pistons are just at opposite extremes of their motion, it may not be possible to get the engine moving again (opposing forces. That's for the real ones. For models, quartering has less to do with the pistons (which aren't driving anything unless you have live steam) and more to do with the alignment of each wheel relative to its neighbors (on same side). Slight misalignments will add up to rough running. Severe ones, like yours, will jam it up six ways from Sunday. Each crank pin will be at a different angle to its neighbor and as such will be out of phase. The connecting rods are yanked around at different angles at each wheel. A little geometry explains that - different angles make for different distances between crank pins. The only thing allowing some movement is slack in the connecting rods. But connecting rods can't stretch, so eventually it will jam up tight. That's the short version. At least for a blabbermouth like me...
Ding, ding, ding! Yes, that is the reason on the prototype! When the drivers are 270 degrees (or 90 degrees, depending how you look at it) apart, the pistons will never be at opposite ends of the cylinders at the same time and thus, will always be able to exert forces to the drivers to get the loco going again. Can you imagine trying to push start a locomotive? Doug
I have seen several steam tractors and even ridden on one for 5 miles. They have very little change in speed and are rather unlike locomotives. On the locomotive the drive wheels are the fly wheels. While the tractor only powers the big flywheel which gets used for many things. To include locomotion.
