Repowering a Doodlebug (Bachmann)

[bbunge]

At least in Ohio, my late father reported, the PRR had signal activation issues with the bugs on branch lines with rusty rails because of their light weight.  The problem was solved by towing around a cabin.  In case you want to try something different.  I've seen at least one photo of a bug/cabin combo.

Bob

[delamaize]

So which chassis did you use.

TomyTec TM-20, that I cut and extended, Similar to how Randgust did his.

[randgust]

Glad to see somebody else try this, as it's the only sure permanent cure for white gear disease.

This is also 'more or less' the same approach Lee Weldon and I did to repower the Bachmann Metroliner.

But if you're really running one hard and often, the first thing to go is going to be that Tomytec motor.  The ONLY motors I've ever had fail in N have been those, all due to brush wear due to heavy use; usual symptoms are random slowing and speeding up as carbon begins to short out the commutator plates and burn off.    You can usually fit an Atlas motor in there just as well if you can pry the old universals out of the flywheels on the Tomytec (not easy but can be done).   Mine doesn't get enough use to be an issue.

[delamaize]

Glad to see somebody else try this, as it's the only sure permanent cure for white gear disease.

This is also 'more or less' the same approach Lee Weldon and I did to repower the Bachmann Metroliner.

But if you're really running one hard and often, the first thing to go is going to be that Tomytec motor.  The ONLY motors I've ever had fail in N have been those, all due to brush wear due to heavy use; usual symptoms are random slowing and speeding up as carbon begins to short out the commutator plates and burn off.    You can usually fit an Atlas motor in there just as well if you can pry the old universals out of the flywheels on the Tomytec (not easy but can be done).   Mine doesn't get enough use to be an issue.

Thanks for the heads up! Mine will not get a ton of use either, Mostly as a Last train of the day, on MRNS N-Trak layout at shows. It is WAY too easy to pull and put away a doodlebug, and a few of the Bachman 65' coaches, than a full Passenger train, or Freight train. And on top of that, it seems to be a popular train. 

[peteski]

But if you're really running one hard and often, the first thing to go is going to be that Tomytec motor.  The ONLY motors I've ever had fail in N have been those, all due to brush wear due to heavy use; usual symptoms are random slowing and speeding up as carbon begins to short out the commutator plates and burn off.   \

Are you sure those use carbon brushes?  In my experience sealed motors of that size with non-replaceable brushes use simple metal-finger brushes which can wear out quickly.  I guess the bottom line is that the composition of the brushes is irrelevant - the important fact is that they wear out rather quickly.

These motors look like some of the inexpensive motors available on eBay.  It might be possible to just buy some inexpensive spares.

[narrowminded]

Are you sure those use carbon brushes?  In my experience sealed motors of that size with non-replaceable brushes use simple metal-finger brushes which can wear out quickly.  I guess the bottom line is that the composition of the brushes is irrelevant - the important fact is that they wear out rather quickly.

These motors look like some of the inexpensive motors available on eBay.  It might be possible to just buy some inexpensive spares.

Oops.   Delete at will.

[peteski]

Oops.   Delete at will.

I can't delete posts here (and I wouldn't anyway). I was simply wondering if Randy took the motor apart and saw carbon brushes.  In my experience that is not the case, but there could be exceptions.

[randgust]

Erratic running.    Slight smoke.   Smell...    Could 'burn it off' by some high-speed running, but next operating session back to same problem.   Time for new motor, which just happened to be my first attempt at a Gizmoszone gearhead and a stunning success.

I'm old school enough that with an open motor you'd just clean the thing out and you'd be good.   No longer have the patience.  These have the 'fingers', and whatever is on them, it was jammed in the slots and burning out.

I have a much older one but it sees only display running, and it's still fine.

I 'think' that Lee's metroliner with the new motor may have the same disease from his reports, not sure.

[narrowminded]

I can't delete posts here (and I wouldn't anyway). I was simply wondering if Randy took the motor apart and saw carbon brushes.  In my experience that is not the case, but there could be exceptions.

OMG. That wasn't about your post at all.  I was going to add something to your thoughts but decided it didn't really add, was too in the weeds, so instead of deleting I hit enter with no post added.  That was what I meant, delete my post.  Yours was fine.

[peteski]

OMG. That wasn't about your post at all.  I was going to add something to your thoughts but decided it didn't really add, was too in the weeds, so instead of deleting I hit enter with no post added.  That was what I meant, delete my post.  Yours was fine.

WOW!  LOL!
You know, while you cannot actually delete a post, you can go back and edit your posts, then simply delete all the contents. Some people just replace it with a "." or even the word "deleted". It is just as easy as that.  The "modify" links are on the top and bottom right of your own posts.

[wm3798]

Haven't had any issues with the motor, at least not yet.  But now you've got me thinking about running it again, so we'll see.
My m.o. is to set up a train to run, and it will run the loops for hours while I work...  Sounds like a an opportunity to torture test it.
I've got several old Atlas and Kato motors laying about, so if it goes teats up, I'll just put it back in surgery and see how it goes.

Lee

[Bobster]

Back to page 3 for a second,

Brokemoto is pretty much on with the Rock Island box cab.  They were basically switchers and light haulers, in the era of steam (before the RS, F and GP units), with a Railway Express section in the back.  There were some joint RI/CBQ operations in Eastern Iowa.  There was even a join train between St. Louis and the Twin Cities, The Zephyr-Rocket, but it had more powerful motive power.  I believe the started as gas powered but later rebuilt to diesel but I may be wrong on this.

My guess is that this is a local in Iowa.  I have pictures of RI box-cabs with RPO's,  a combine, and with a RI RPO and RI coach (captioned as Lincoln Nebraska).

In addition I have seen an article somewhere of a Rock Island box-cab being done in resin or 3D.  Sorry I just can't find the article.  I'll post a link if I can find it.

Bobster out

[bobthebear]

If you are looking for replacement gears - my son, Jamestrainparts, has them, 3D printed.

[wm3798]

Pleased to report she's been running all afternoon without incident.

Lee

[Sumner]

First off thanks so much for posting the repowering of the Doodlebug.  I just bought one and it doesn't appear to have broken gears (runs quiet and slow).  I should leave it alone but would like to possibly do the Tomytec drivetrain swap.  My only current problem is the rear trucks seem to have a mind of their own on a couple of my turnouts and derail where other engines don't. Maybe add some weight to the light end?

Anyway a couple questions about your build.  At first it seems you are using the TM20 chassis and then you mention the TM23 chassis a few times.  Looks like the 23 is 16mm longer.  Is this the one I should buy?

You mention pulling the traction wheels.  From pictures it looks like there might be two axles with them?  I'm assuming you replaced them with axle/wheels from other builds that you had.  I've searched a lot and can't find individual Tomytec non-traction geared axle/wheels that I could order and use.  Are you aware of how/where they could be ordered?  Having to buy another complete chassis would probably put an end to doing this.

Other than looks would there be a downside to running with the traction wheels?  I don't have any engines with them so no experience with them.

Thanks for the help and the great build,

Sumner



 TM20 is narrower than the shell, by about .040.