Looking for help with re-powering an N scale steam locomotive

Robotics and electronics discussion Mechanical design and actuators
1

I just acquired a fairly old Atlas N-scale 0-8-0 steam locomotive in amazingly good condition. However, the motors they used back then were…less than stellar, and my example has a catastrophic failure therein. The armature has come completely separated from the commutator and I lack the equipment and skills to repair the existing motor.

I am scouring the web for a replacement motor that does work, but even if I do find one another failure is likely as the issue here is with the basic design. So I’m here, wondering what you all would suggest I use.

Approximate dimensions:

Can length: 14mm
Can diameter: 15mm
Shaft length from end of can: 12.2mm
Shaft diameter: 1.5mm
Voltage range: 12VDC nominal, but my power pack can run as high as 17VDC.

Desired operating characteristics:

Smooth
Low current(Typical current draw is between 200mA and 750mA)
Low heat output
High torque at low speeds
Low-ish top speed. Something in the 6-7k RPM @ 12v area would be pretty good.
Runs equally well forwards and backwards.

I would just buy one of the metal gearmotors Pololu sells, but their output shafts are far too large and I cannot machine them down to something suitable. The small plastic planetary pager motors would work, but they have the same shaft size and their 6V max rating means they are prone to burning up in this application(Though, later on with digital control I could cap their max voltage and run one, indeed other railroaders have used them as such).

Any suggestions?

2

Hello,

Unfortunately, the only gearmotors we carry that are close to what you are looking for are the ones you have already eliminated. I do not have any recommendation where you might find replacement motors like that. You might consider looking for a model train-specific forum where they might have contacts for replacement parts.

-Derrill

3

I do machining at the Tech Shop, but I once home-machined an axle down to size by sticking it in an electric drill and holding a file against it while it turned.

I would imagine you could get a small motor from Pololu with the too-bit shaft, and actually run the motor itself while holding a fine-toothed file, or something else abrasive (side of an angle grinder?) against it, until you got it to size. The trick is to apply enough pressure that you’re actually cutting, but not so much that you stall the thing that turns or end up scoring/gouging the axle too deeply.