Introduced: 1983
Although a very pretty model of a very interesting prototype, these are (for the most part) some of the worst running models ever rendered in brass (not surprising, given Kumata's iffy reputation when it comes to brass locomotives). These models are pretty rare (they hardly ever show up on eBay, that's for sure). And despite the finicky mechanism, they generally sell for premium prices (ranging from $600 to as much as $1600, depending on condition and paint scheme). This, I suppose, having more to do with the desireability of the prototype and the deep pockets of PRR modelers than anything else.
These models were available either with or without a PRR-style trainphone antennae. And as far as I know, they were all delivered undecorated. A set of four step-ladder extensions is included in the box. However, since they tend to interfere with the trucks' ability to pivot (thus leading to short-circuits), they are likely only good for static display purposes.
The mechanism is a real departure for Kumata; consisting of two simplistic truck assemblies (each with its own motor) that attach to the shell by way of a pair of swiveling bolsters (as pictured below, located between the worms and the motors) -
The motors are 12 x 20 mm Sagami cans that turn single metal driveshafts (each driveshaft being equipped with a really huge brass worm). Two of the four axles on each of the center trucks are geared (with all the gearing being brass). The end trucks are screwed to flimsy brass offshoots coming off the center truck assemblies. Large metal weights screwed inside either end of the shell provide most of the model's heft. As delivered, there are no traction tires. However, a set of four TT-equipped wheelsets is included in the box. There are no lights, window inserts or couplers. Wheels are low-profile, so no problems on Code-55 rails. These models are happiest on 19"-radius turns or broader (any sharper than 19" and they tend to want to derail).
The pickup scheme is quite bizarre. Right rail pickup is provided by all twelve right-side wheels (with current flowing through the chassis before ultimately reaching the motors by way of wires). Left rail pickup is provided by wipers that contact the tops of the four geared wheels on the left side. Current flows from the wipers to the motors via wires. Right-rail current is shared between the two truck assemblies by passing through the shell, whereas left-rail current is shared by way of a wire running between the two truck assemblies.
Note that the axles collecting right-rail current rub directly on their respective truck assemblies. Consequently, you're going to have to occasionally pull the bottom plates off the trucks and give the axles and axle "pockets" a good cleaning in order to keep things running. And be careful how you go about lubricating the truck gears. Any sort of traditional lubricant is going to foul the geared current-collecting axles, so I'd suggest using something like Conductalube instead.
Generally speaking, these models have a lot of problems in the performance department. If any of the flimsy metal that makes up the trucks and/or truck bolsters is bent (or even slightly out of skew), the loco will barely be able to move itself (let alone pull anything). Performance can also suffer rather drastically if the two motors aren't perfectly speed-matched (and given the cheap motors, this seems to be the case more often than not). And then you have the whole "all-metal gearing" situation. IE, even if you got lucky and your 'pede runs well, it's still going to be fairly noisy.
As it happens, I managed to acquire one of these that runs quite decently. It's smooth (albeit a bit a noisy) and has no problems pulling sixteen 85' passenger cars on level track (mind you, that's with the TT-equipped wheelsets installed and extra weight added inside the shell). So, yes, it is possible to find one of these that runs acceptably well (or can be tuned to run acceptably well). But that seems to be the exception rather than the rule.
To remove the shell, unscrew the four screws that hold that two bolsters to the shell.
Grade: F (although right around a "B" if everything is put together correctly and the motors match up well)