Steam loco binding


I

ianc

Member
I've been working on scenery for a week, and having finished ballasting the track thought I'd see how well the loco performed on the track. It didn't. It's a Minitrix 4-6-2, and wasn't working when I first started this project, but replacing the wire from the tender to the motor, and cleaning and oiling, made it work pretty well. It was working when I set it aside a week ago, although it needs new traction bands. But when I tried it after a week's rest, it wouldn't move. So I took the shell off, and found that I could rotate the wheels 180 degrees in either direction, whereupon they stuck. I removed the motor, and it runs fine. By working the wheels back and forth (no motor) I can now turn them 360 degrees with only a slight bind at one spot, but if I turn them in the opposite direction there is a pretty hard bind in that one spot until I've made two or three revolutions, whereupon there is only a slight bind. I can't see any sticking of the con rods, the opposite pins are 90 degrees to one another. The drive wheels have some side play, maybe 5 thou. Any suggestions? Please? This thing is driving me nuts.

Thanks in advance.
Ian Cameron
 
I tried answering earlier but my pad malfunctioned.
I had a similar problem with a Con Cor Mallet. Same thing with the wire (bad design). I discovered that one of the rods had a slight bend in it from years of good service. These things are very touchy and easy to unbalance. It took a few hours with the magnifier on to get it tweaked and it ran for a bit. Then the pick up wire came off again! Once these boys start coming apart they are difficult to maintain.
The drive wheels may be drifting enough to do what you are saying. If you haven't tapped or dropped the loco, you may be able to gently press them a bit tighter. If the wheels rotate freely without the rods on, then set the engine on some track and see how much it moves side to side with the rods on. Gently throttle it while you are doing this and see if the wheels rotate full turns. and make note of where the loco is when they rotate. It is a pain but I like working on this stuff and have had pretty good luck repairing old steamers in the past. Con Cor and Trix engines are a different breed but worth the effort once they get sick. Let us know how you do on this one.
 
We sometimes get this problem on HO and larger steamers. Most of the time its the rods binding against a wheel, counterbalance, valve gear, or maybe even another rod. You definitely need magnification to see it. Brooksie had it right. You have to bend the rods in such a way that when they are free wheeling, (without the motor in), the mechanism can roll across a pane of glass without binding. If the problem is the wheels can't stay in gauge on the axle, there is also a good chance that they will also get out of quarter. When there is no replace available I will first try securing the wheels in gauge with a good hard 24hr epoxy. If that doesn't work, I'll try using a key on the axle or drilling through the axle and wheel and then pin them together. Plastic centered drivers are prone to develop fatigue cracks, and the epoxy has worked well for this kind of repair.
 
Thanks to both of you. I'm in the process of taking off the side rods to see if I can get the drive wheels to rotate freely. I'll let you know.

Ian
 
Once you do that when you start to reassemble the mechanism, put one part back on at a time, roll to check for binding. If none there, put on the next part, and roll again. Continue until the mechanism is reassembled and rolls freely.
 
Best of luck Ian. It is sort of fun doing roundhouse work, isn't it?
Now, maybe you can tell me how you keep that confounded pickup wire in place between the tender and cab!
 
I don't think its a valve gear bind but its out of quarter. Much harder to fix on an N gauge steamer.
 
brooksie said:
Best of luck Ian. It is sort of fun doing roundhouse work, isn't it?
Now, maybe you can tell me how you keep that confounded pickup wire in place between the tender and cab!
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I used a piece of wire much longer than needed, so there is plenty of slack. I attached it with silver epoxy. So far, so good, but it didn't run much before binding. But I've been handling the loco/tender quite a bit, and the wire is still in place. (Now, of course, the next time I touch it..............)

Ian
 
ianc said:
I used a piece of wire much longer than needed, so there is plenty of slack. I attached it with silver epoxy. So far, so good, but it didn't run much before binding. But I've been handling the loco/tender quite a bit, and the wire is still in place. (Now, of course, the next time I touch it..............)

Ian
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Thanks Ian! I've been reattaching the same old wire for a couple of years with no avail. I'll try this. Take care and good luck.
 
brooksie said:
Thanks Ian! I've been reattaching the same old wire for a couple of years with no avail. I'll try this. Take care and good luck.
Click to expand...

I used 30 gauge wrap wire. It's solid, it's flexible, and it solders easily with heat or cold solder (silver epoxy) although it's supposed to be used in place of solder on small, heat-sensitive components. (Hence the 'wrap'.) 100 feet cast about $8, and will last you a life-time.
 
bklynman01 said:
Ian, I had a similar problem recently with a locomotive. I tried to put a bunch of pictures to show the problems I had. Check it out:

http://www.modelrailroadforums.com/forum/showthread.php?33616-Cheap-Steam-Loco-Needs-Some-Help

And please, post what your problem and solution end up being. I have a couple of other locomotives that need some help, so these threads help me a lot!
Click to expand...

Well, I got it. I removed the titchy bolts that hold the coupler rods to the rear drivers, and pried out the titchy pins that pin the rods to the middle drivers. Then I removed the base plate (??) which allowed me to remove the drivers. The front drivers bound, the mid and rear didn't. I swapped the idler gears (??) with no effect. Putting the mid and rear drivers in the front position, both turned freely. Putting the front drivers in the mid or rear position, they bound. So it was the front driver gear. It bound in the same position clockwise or CC rotation, so I inspected the bottom lands in that area with a high-powered magnifying glass. Nothing. Then I cleaned them with a pin. Nothing. Again. Nothing. Third time. And a tiny speck appeared on the white sheet of paper above which I was working. And voila! the front drivers turned. Now all I have to do is quarter the drivers, attach the couplers with those titchy bolts (using a drop of white glue and a finishing nail) and figure out how the dummy valve gear attaches. With luck, there's a picture of the speck on a business card, under a line of 12 pt type.
IMG_0275.jpg
 
ianc said:
Well, I got it. I removed the titchy bolts that hold the coupler rods to the rear drivers, and pried out the titchy pins that pin the rods to the middle drivers. Then I removed the base plate (??) which allowed me to remove the drivers. The front drivers bound, the mid and rear didn't. I swapped the idler gears (??) with no effect. Putting the mid and rear drivers in the front position, both turned freely. Putting the front drivers in the mid or rear position, they bound. So it was the front driver gear. It bound in the same position clockwise or CC rotation, so I inspected the bottom lands in that area with a high-powered magnifying glass. Nothing. Then I cleaned them with a pin. Nothing. Again. Nothing. Third time. And a tiny speck appeared on the white sheet of paper above which I was working. And voila! the front drivers turned. Now all I have to do is quarter the drivers, attach the couplers with those titchy bolts (using a drop of white glue and a finishing nail) and figure out how the dummy valve gear attaches. With luck, there's a picture of the speck on a business card, under a line of 12 pt type.
View attachment 41816
Click to expand...
On my Con Cor locos, the dummy gear actually floats about the wheel at the mark. In reality, the rods are simply decorative. Just for comic relief: I had my 2-8-8-2 apart and checked motor and gearing for a similar issue and it was fine. The rods on the front truck (articulated) kept coming loose. I used tools to unscrew the whole set and checked them for straightness and one "dummy" rod was bent slightly and kept falling off. I fixed it and when putting it back together one of the tiniest screws in the world came off the magnet and is nowhere to be found. Now I have this engine that is ready to run and the doggone screw that holds the rod assembly on jumps off the table! Don't it figure? I am going to check the hobby shop RC department with the other screw and see if they can help.
Your thread has been a great help!
 
And to make matters worse, that 'screw' is probably the world's smallest bolt. I hope you find a source.

Ian
 
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