These gorgeous looking and smooth running models were designed in Japan by More Co and manufactured in Korea by LIK Enterprise Inc. They rarely show up on eBay, so be prepared to pay through the nose to acquire one (full retail is/was $1580).
Internally, the mechanism is designed very much along the same lines as the articulateds built by Samhongsa for Key.
The two-part chassis is all metal and fairly minimalistic (with most of the actual heft being provided by the shell). Like the prototype, the forward engine is articulated (IE, free to pivot), whereas the rear engine is fixed in place to the shell. The large motor has no markings, but I'm told that it's a coreless Canon. The motor is mounted to a vertical bracket, giving it a bit of up-and-down freeplay. A short plastic/rubber connector joins the motor driveshaft to the rear worm shaft. A series of articulated plastic connectors then join the rear worm shaft to the forward one.
Right-rail current flows from the six right-side drivers into the chassis (and then on to the motor by way of an insulated mini-wire). Left-rail current is collected by the six left-side tender wheels and then transferred to the locomotive by way of a single stiff wire on the tender drawbar. An insulated mini-wire inside the locomotive then transfers left-rail current to the motor. All the rest of the wheels are electrically neutral.
A pair of wires (equipped with plug/socket connectors) runs from the motor up to the electronics for the directional headlight mounted inside the front of the shell. Another pair of wires (also equipped with plug/socket connectors) runs from the electronics down to the pilot-mounted headlight. The tender is not equipped with any sort of lighting (although a backup light detail is built into the tender shell).
There are two geared axles (the rear axle on the forward engine and the center axle on the rear engine). All the rest of the drivers are turned solely by the running gear. The driver axles are held in place by brass bearing blocks that seat inside of cutouts in the frames. The bearing blocks for the non-geared drivers are mounted on coiled suspension springs. The pilot truck is also sprung. All of the gearing is brass. Wheels are low-profile, so no problems on Atlas Code-55. There are no traction tires. There aren't any couplers either, although MT-friendly mounting pads are provided on the tender chassis and the pilot.
Performance is outstanding in every way. Mine runs smoothly and quietly at all throttle levels. Despite the drawbar wiring setup (usually a source of trouble on these brass locos), I didn't experience any pickup or conductivity issues. Slow speed creep is excellent and the top end speed is very reasonable. Pulling power is impressive (especially given the lack of traction tires), with mine comfortably able to haul fifty assorted freight cars on level track. I'm not sure what the minimum radius is for curves, but it definitely can't handle 11"-radius or sharper (not too surprising, given the non-articulated rear drivers). 19" curves aren't a problem, so my guess would be somewhere in the 15"-16" range for a minimum. Overall, just a superb loco that is well worth the rather steep asking prices.
SP&S version -
Shell removal is a bit of a bitch (surprise, surprise). First, remove the two small screws on the back of the cab (near the bottom). Next, remove the two screws that hold the rear chassis to the shell (they can be found on either side of the screw that holds the forward chassis to the rear one). Next, remove the two screws that hold the articulated steam pipes to the front of the shell. And now the "fun" part - there is an articulated steam pipe screwed to the center of the forward chassis that seats inside of a long slot in the underside of the shell. You must slide the shell far enough forward to allow the fat end of the pipe to pop out of the round opening at the end of the slot. Oh trust me, it's just all sorts of fun (and getting it back into the slot during reassembly is more fun still). Enjoy!
(Thanks for the loaner, Tom!)