Critter power - two new(er) choices

[randgust]

Most of you know that I've been attempting industrial locomotives for quite a while, and have operating models of a GE 25-tonner, EMC40, trackmobile, and my bitty Burro crane.

So I'm always on the lookout for tiny commercial mechanisms.

There are two that are out there, reasonably 'new' that deserve commentary after I've had a look at them.

The first - and possibly the wierdest - is the Tomytec HM-01.   What this really is is a powered single Tomytec truck.  It's a solid design, pretty much what I unsuccessfully tried to do on my own -  a worm drive to the offset gear tower, on a 7' wheelbase truck.  End-axle pickups, very low friction.  I just got one and was astounded how well it ran, as what it has is essentially the Tomytec 12V motor worm-driven to a truck.  Bigger 12v motor, similar to Bachmanns.  My testing shows excellent pickup. 

What's wierd about it is how it's marketed, if you could read Japanese.  It comes in a brightly colored small cardboard box, sort of like a candy box, with cartoon characters on it.   The 'body shell' if you could call it that, is an undetailed plastic box.   And it comes with stickers.  Blank ones, so you can apparently draw on it and put stickers on the shell?   This looks solidly targeted at younger children.  They must not have the same 'contains small parts' rules in Japan is all I can say.    Plazajapan has these, and the price is very reasonable.
http://www.ebay.com/itm/Tomytec-HM-01-Hakotesu-Powered-Motorized-Chassis-N-scale-/351484502870?hash=item51d61be356#ht_4296wt_1098

The second oddball is the  TU-7T - Tsugawa Yokou 14008, which on the surface looks like the ideal chassis for a 25-tonner.  The good news is that it's fairly well-made, 4 wheel drive and 4-wheel pickup (unlike some of the tiny chassis out there).  The bad news is that it's basically a 4.5v. pager motor in a 12v world, and you can't make miracles happen with a motor that tiny.  The controllability is marginal.   Design-wise it's an absurdly short wheelbase (even too short for a 25-tonner) which makes stalling over switches even worse. 

It is small enough to essentially drop into a Shapeways-printed 25 tonner shell, which is more than intriguing.
http://www.ebay.com/itm/Super-Mini-Size-Motorized-Chassis-TU-7T-Tsugawa-Yokou-14008-N-scale-/201396032572?hash=item2ee423943c#ht_3243wt_1224

The vertical shaft design is 'more or less' what I came up with for my 25-tonner, so I'm planning on grafting one of the much better and bigger 12v critter motors from the 11-105 into it to see how that goes.  Stay tuned, I may do construction threads.

You do have to beware that many of the absurdly-tiny 'pager motor on a roller skate' designs out there do not have 4-wheel drive.  I managed to get one of those jammed inside my Burro crane, and it worked - but only because it was heavily weighted over the one powered axle, and because I permanently mated it to a flatcar with 8-wheel pickup using Kato caboose trucks.  While it's not identical, this is pretty close to it:  http://www.ebay.com/itm/Super-Mini-Size-Motorized-Chassis-Pro-Hobby-Ca-ND-1-Kai-N-scale-/351468621105?hash=item51d5298d31#ht_2959wt_1098
On the one I had, the flanges were so rough and the wheels so out of gauge that I had to redo it with Kato wheels, but then it actually worked OK.  At least it was a 12v. motor.

[wazzou]

Is the first one a good candidate for a third truck on the Atlas 2 truck Shay?

[randgust]

A typical Shay has 33" wheels on a 48" wheelbase; this has more like 36" wheels on a far longer wheelbase, that's always the problem.  The Kato critter truck is 27" wheels on a 5'6" wheelbase, which is how far I compromise down.

If you could live with that wheelbase, yeah, it's a very robust drive and very well made.   It's probably the most robust single-truck drive I've seen in that price range.   It's also equalized, and there's just enough wiggle to allow the truck to stay in electrical contact.  The 'trick' is that the Tomytec truck puts the gear tower all the way to one end, so you can mount a motor on the truck itself.  The various adapters and clips they have designed to hold it together make it a bit 'fat' to fit it into a diesel hood without a lot of modification, but the fatal flaw I hit before was that the motor shaft was too darn short to mount a worm on when I tried to self-power a truck with the same concept.   So now, if I can thin it down, there's some potential here for other applications.   I've had extremely good results with Tomytec parts in both my Whitcomb kit and the powered boxcar - they are every bit as well-designed as Kato.  Walthers is now carrying some of their chassis, which is about time, because there's just a wealth of stuff out there.