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I've been making a 2-8-0 from a couple of Bachmann 4-6-0 ten-wheelers, and I'm now tearing my hair out.

I'm testing the fit on my new chassis to make sure it all revolves. Here's a pic of the first time I assembled it.



So here's my problem, which I'm hoping someone can shed some light on, or at least tell me what I've missed.

When I put the wheels on and test the coupling rods, as you see above, it turns out the blind drivers are quartered - the rod bearings are exactly 90 degrees from each other. The flanged drivers are not!

The blind drivers are a pair of identical cast wheels and stub axles, with a squared end:



They fit into a plastic sleeve with a square hole through it, (still attached to the RH axle) so by definition, the wheels will always be 'quartered'. You might think this a little flimsy, but they don't have to do anything except look pretty and rotate, so it works.

The flanged drivers are a different kettle of fish. There are 2 kinds, with a '1' or a '2' cast on the front. The difference is the angle of the shoulders in the casting that hold the nylon insert:



Here's the pair. The axle has two flat ends which are parallel, so when you push the wheels on the axle, they end up at the angle assigned by the shoulder inside the hub.



Here's a better photo of the wheel. The nylon sleeve insulates the wheel (and lets it rock and roll.) You can see the shoulder inside the hub.



But when you put the wheels on the axle, they are not at 90 degrees - more like 110 or 80 degrees. The above red lines the approx angle of the nylon insert, and the yellow ones are the position of the boss for the rods. [Having 11 spokes doesn't help the visuals!]
I must be missing something, because my other ten-wheeler locos seem perfectly quartered and work fine. I can't believe B'mann changed the casting just for me. Any ideas?
 

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Well, I may have found the answer...

Yesterday evening I started checking the alignments, and the shoulders in the holes in the wheels seem to be cast at right angles. The #1 wheel has the shoulder in line with the boss for the rod, and the #2 wheel has the shoulder at right angles to that. (Or vice versa - I put the inserts back in so I can't see the 1 or 2 now!)

So, as the following drawing shows, the wheels should be correctly quartered.



While working this out, I happened to use my parallel-jaw caliper to check that the shoulder was aligned with the boss, and noticed this:



The jaws are tight on the flats that fit the shoulders in the wheel - and the slot in the bush for the axle isn't on the same plane!!!

It seemed obvious that, inserting the bushes from the back of the wheels, so that one bush is reversed from the other, will get twice the displacement, so I got to work on the drawings again. [The red/blue pair of lines represent the bush squared sholders - one inside and one outside.]





And that confirmed my first thought - that if I kept the bushes aligned, inserting one from the inside and the other from the outside, then the wheels would stay at 90 degrees.

How can that be? Is this a new batch of bushes - and how did the original configuration ever work? Is there so much play in the standard attachment that the wheels work anyway? [Can't answer that - I'm too far down the path of making something different to put everything back!]
Sorry if this bored you all to tears, but at least it is now in the archive for the next poor fellow, or someone who wonders why his ten-wheeler drivers are binding.[/i]
 

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Bored to tears??? Not even close. Very interesting problem. I can think of a couple of reasons why you may be seeing a difference, since I'm assuming one would expect all the bushings to go in from the same direction. But possibly not so? Or, more likely, you've mixed wheelsets from two different production runs. This last is my best guess.

In short, I simply don't know. But I'm REALLY glad you posted, because I've got several B'manns that are headed for the butcher shop. Eventually.

I've noticed, from dabbling in various interests (always on the low end, where parts/repairs are needed) that I used to be amazed at how two exactly alike items, right down to first few numbers of the s/n can have minor (or worse) differences, straight from the factory. I discovered this when trying to order replacement parts.

A good example jumps to mind. I have a '94 S-10. The Book says, 16" wiper blades. I buy them. They are too long to fit the arms. I go back into the parts store and the guy (a real, honest parts dealer) goes and measures mine. "You have 15 in. blades." I say, "How could that be?" He answers, "When it came down the production line, they didn't have the right arms ready, so you got what they could find fast. Happens all the time." And proceeded to tell me of all the rolling misfits out there.

Les
 

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That sort of thing happens all the time with LBCs. (Little British Cars). Sure, something like the waterpump/pully combination was supposed to change from the 1968 to 1969 model year, but my early '69 still has the '68 pump and pully because the assembly line just used up all the '68 pumps on hand before changing over to the '69s. Many cars have also been 'repaired' with used parts from other cars, so even using the VIN number cannot guarantee you're ordering the right part. I learned very quickly to always save the old part for comparison to the replacement. I've read that International Harvester pickup trucks (remember those ?) are also notorious for this.
 

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Discussion Starter #8
Rod, I did get your post about the insert bushing "slipping around" - which prompted me to look real closely at the assembly. (Thanks! I did reply on 12th.)
 

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Slim,

IHC trucks were terrible in that respect. With tractors, most people expected mid-production-run changes and dealt with them. When they started doing that to IHC light trucks as well, it became necessary to have the S/N of the engine, if an engine part, OR the VIN (Vehicle I.D. No) if a non-engine part. It forced an owner to go to the IHC parts place instead of a standard parts store. A friend of mine found out the hard way after burning holes in several pistons from using the 'wrong' spark plugs, bought from a well-respected aftermarket parts source. His truck had an engine different from the normal from that production run.

Les
 

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Hello, There is a possible way around this, I had a simular problem some years back while doing


a Project very simular to yours, In the end I Filed the Plastic Unit Hubs which allowed me to


set the Wheels in any Quarter I wished, I then set about making a Quartering Jig to assist


me in setting up all eight Wheels, then Glued the whole lot very carefully using "Epoxy Glue".


which locked them up beautifully.


I needed a very small amount of Licence in the Connecting Rod clearance department!.


All went very well!.





Hope this helps!.


John.
 

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In the end I Filed the Plastic Unit Hubs

John,

Thankis for the input. I actually started filing before I stopped to think about what was going on. I filed the shoulders of the wheels, figuring that a little play there would let me get the wheels back to 90 degrees without too much effort - and of course epoxy would keep them there!

Any pics or info on your quartering jig? I've been doing it by eye, as these wheels are 2 3/8" diameter.

Licence in the Connecting Rod clearance

Yes, that's my next problem. I tried to set up the rods when I drilled the chassis but it didn't work. I have a jig for soldering new rods so hopefully it will not result in too much play. However, the original Big Hauler plastic rods have a huge amount of play and they still work.

[added 11/17]
On the subject of modifying connecting rods...

I originally tried melting the rods to shorten them. Not too bad - they are hard engineering plastic/nylon, so they burn and bubble and run nicely. The problem is getting all 6 joints to work and not melt the bosses, and making them look nice. I finally gave up, and bought some rectangular brass tube the right size and brass washers, but using the latter means a lot of filing and fitting to make it all work.

I cut down the rods and shrank them to fit the tubes, with some judicious soldering iron application to force the final fit. Them I drilled and fitted 1.2mm bolts to hold them together. There's a bit of looseness, which is probably a good thing. And they look OK - better than the melted version. Here's a pic of the rod I did yesterday - the left hand side is a melted version.
 
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