Powered Stewart Models 25 ton rail crane

[Jim Starbuck]

I’m no Max, Chris, Randy or Ron but I do like to build small mechanisms.
After all…”They’re even cooler if they run.”
I’ve had this Stewart Models 25 ton crane kit for about 15 years and always thought it would be nice to have it powered. Having some success with the slim coreless motors on some other projects I decided to give the crane a go.

The Stewart kit is kind of crude but it’s about the only game in town for this particular model.
I made a new chassis from styrene which would be much easier to work with than the white metal chassis from the kit.
The trucks are leftovers from two 11-106 Kato powered chassis that I used for my Davenport 45 tonner build.
The rear truck got a Kato geared axle tube and is mounted rigid to the chassis. The front truck pivots on the original mount cut from the donor chassis and epoxied to the new styrene.
With this being so short it still goes around tight curves just fine with only one truck that pivots.

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I made a casting of the swing gear from Milliput epoxy putty then glued it to the chassis and fit up the car body.

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The original plan was to use a tiny 4mm 3 volt coreless pager motor. I built a mount from brass and although it did run, I couldn’t get acceptable slow speed even after fashioning a gear reduction so I abandoned it in favor of a 6mm 12 volt coreless.

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The 6mm motor utilized the same mount and drives the axle gear directly from the worm. It runs nicely.
Even with the larger motor I was able to fit an ESU Lokpilot V5 micro decoder as well as an Iowa Scaled Engineering keep alive in the car body.

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In the video it’s pushing a 42’ flat car which will be the tender but the crane is electrically independent and seems to do just fine.

I’m happy with the way it runs so now I can proceed to building the rest of the model.

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Jim

[garethashenden]

That runs nicely! Will you be motorizing the crane too? 

[Chris333]

Wow it does run good.

[Jim Starbuck]

Wow it does run good.

Thank you Chris!

[Jim Starbuck]

That runs nicely! Will you be motorizing the crane too? 

Thank you.
The plan is to have the boom rigged low in the traveling position with lots of rigging, blocking and a clam bucket on the tender flat.

[BCR 570]

Hi Jim

Well done - your project is of interest to me as I had envisioned a similar conversion.  I have the Stewart crane and a Kato 11-5 chassis but was stuck on how to power it.

Tim

[Jim Starbuck]

Hi Jim

Well done - your project is of interest to me as I had envisioned a similar conversion.  I have the Stewart crane and a Kato 11-5 chassis but was stuck on how to power it.

Tim

Thank you Tim,

The trucks I used are the non geared from two Kato powered chassis. The main reason for putting the geared axle tube on the inboard side of the rear truck was to allow the worm to drive above and forward of the axle and letting motor protrude up and rearward in the car body. I don’t know if there would be room to drive a geared truck from the top center. You may be able to mount the truck rigid and use a crown gear like HO slot cars use and possibly use the Kato motor mounted vertically.
I cut the entire floor out of the cast carbody. Everything is mounted on the styrene chassis and the carbody is set down over the top like a regular locomotive shell with screws holding it from the underside.

[mmagliaro]

That runs GREAT!  Nice job!
The 8 wheel axle-point pickup is definitely the ticket here.  And you've got all that weight on it.

About the motor - yes, the difference between a 4mm coreless pager motor and a 6mm coreless is night and day.
The only other thing you could do is use an axle tube from the Kato SD-40-2 mid production, which has a mod 0.2 gear on it
instead of the mod 0.3 you now have.   You would have about 30% more teeth, and thus 30% more reduction.  You would also need the Kato worm from that engine (or from their GG-1 which is the same mod 0.2).  That would all get you more torque to the axle and
even better lower-speed running.

But to be honest, I think if I had an engine running as good as your is, I'd leave well enough alone!

[Jim Starbuck]

Thank you Max,

The geared axle tube is from Kato 932090 wheelsets where I used the wheels to replace those on other engines. The worm is from a Bachmann S4 that I bored out then made a bushing for the 1mm motor shaft.
Basically these were used because I had it all on hand. I’ve been reading yours and Ron’s threads where you talk about the different mod gears and worms. I don’t know much about the gearing but really interested in learning more.

[Chris333]

The teeth are finer. So the same diameter gear can end up having more teeth. If the axle had 15 teeth it would be a 15:1 ratio. If Max says the finer gears are 30% more then you could have a 19.5:1 ratio in the same space.

[Chris333]

Check out some of this guys videos. He has a few N scale chassis with stepper motors in them that seem to creep slow. Of course there are all those electronic I don't understand.

https://www.youtube.com/user/diorama111/videos

[Jim Starbuck]

Check out some of this guys videos. He has a few N scale chassis with stepper motors in them that seem to creep slow. Of course there are all those electronic I don't understand.

https://www.youtube.com/user/diorama111/videos

Cool stuff!
Thanks Chris

[sirenwerks]

Sweet!  And I just scooped up one of these off of eBay for a good price.

[randgust]

OK, so I've been a fan of critters, and cranes, forever.    I did a Stewart 25-ton crane way back in the 70's and wrote an article about how a local factory was using one for a shop switcher.   (NMRA Bulletin).  FYI it switched freight cars around the mill, but made a shambles of the gates, fencing, anything else it could hit with that boom.   Photos if you'd actually want it.

And while I've made a working Railway Express Miniatures burro crane (video on YouTube) the Stewart 25-ton was left to work train service as an unpowered crane.   Never could see a practical way to do it, even with the Kato trucks.

But this is so off the wall, creative, and brilliant an approach I'll give it my thumbs up, particularly abandoning conventional thought and fixing one truck in place an driving one axle only.   And it runs well.

I've paired mine with a drop-end gondola full of all the rigging, an REM bucket, separator bars, etc. so that it's in work train service (not a wrecker) and with a 50' gon that boom is protected.   But it's completely prototypical to use one like a critter for industrial switching.

Because I've been buying Kato chassis for the parts for built-up Nn3 Climax A's, I have a surplus of those regular trucks if anybody is stuck.  PM me.

[Jim Starbuck]

Thank you Randy.
Your name should be included in the first sentence of this thread too as one of those crittermeisters whose work I look up to.
I’d love to see a photo of your flat car tender and how you populated it with the various rigging.