These models (RS-1, RS-2, RS-3, RSD-4/5) all came out at the same time, and as such I'm going to go ahead and assume that they all sport the same basic chassis/mechanism. So, to save myself a bit of time (and money), I'm going to review them all here based on the couple of RSD-4/5's I've actually purchased.
So anyway, yep, they're brass and they look great. OK, we got that out of the way. Now on to the dirt...
These Kumata Alcos have a very bad reputation. From what I've been told, they had a lot of manufacturing defects which resulted in various maladies. And apparently the main problem was with the poorly designed brass chassis and its propensity for bending and warping - the net affect being a lot of excess noise and friction if you got one that wasn't spot-on perfect, and flat-out locked-up truck gears if you got one that was really messed up. Making matters worse is the fact that the truck towers were manufactured using some really iffy "Zamac". As a consequence, it is becoming increasingly difficult to find one of these models where the Zamac trucks haven't started to disintigrate.
The motor is a fairly small open-sided 3-poler. Large worms are attached to the dual driveshafts and mounted inside of gear boxes. All of the gearing is metal. Each truck picks up a single rail (with the wheels on one side of the truck providing pickup and the wheels on the other side providing not a damned thing). Current is transferred to the motor via the chassis itself (from one of the trucks) and from a wire connected to the worm gear box (on the other truck). Two axles on each truck are geared (IE, on the 3-axle truck units, one axle is a total idler). The model has no lighting, no window glazing, and no couplers (although coupler pockets with ready-to-go screws are provided). There are no traction tires either, although that isn't necessarily a bad thing.
The two RSD-4/5's I've actually purchased pretty much bear out all the bad news I've heard about these things. The first one had that whole warped chassis thing going on, and as such it ran as hot as the sun, made more noise than an 80's metal band, and had all the slow speed performance of, well, something that doesn't have any slow speed performance at all (sorry, my metaphors have failed me). The other one had decent running characteristics at the chassis level but, for whatever reason, the truck gears were all screwed up and would constantly bind up for no apparent reason (Zamac-itis, maybe?)
So, I took the good trucks from the bad-chassis RSD and the good chassis from the bad-trucks RSD, put them together, and made something that, I guess, is about as good as it gets for these models. And yes, it runs around in circles pretty decently. A bit loud (but not horribly so), smooth throttle response, decent slow speed performance, etc. Overall, I guess about on par with some of Bachmann's 1970s-era trainset locomotives. Unfortunately, the pickup situation was the ultimate killer. With each truck only picking up a single rail, these things are absolute dead ducks when trying to navigate turnouts with non-powered frogs.
So, ultimately what we have here are some models that will look very pretty sitting in a display case. But forget about running them on a model railroad.
Removing the shell is pretty simple - just unscrew the two screws holding the chassis to the shell (one on either end, underneath the trucks) and it should pull right off.
Reviewed: 9/83 Model Railroader ("One of the most common pleas of model railroaders is for someone to offer Alco road switchers (RS-1, RS-2, RS-3). Hallmark Models has been paying attention and has imported these three models in N scale brass. The model we ordered for review is an RS-1. The Hallmark model matches exactly the prototype dimensions. Everyone who looks at the model comments how nice it looks. One staff member, looking at a photograph, thought it was an HO model... The handrails are about as fine as you could get; if you went any smaller anyone with less than 20/20 vision couldn't see them. Details like louvers, doors, and hinges are finely etched in the brass; and soldered-on details such as filler caps, stack, and horn are neatly applied. As a display model it's an exquisite piece. I have only one criticism with regard to the model's appearance; the handrails obstruct the steps. You'd have to have an N scale crew of real string beans to work this engine! The position of the V-shaped stanchions in the center of the platform is too far in toward the hood (also, the handgrab should through, not behind, the stanchions), and so the handrails had to bent back out at the bottom... So much for the cosmetics. How did it run? Perhaps not as well as you'd like for a switch engine, but better than most N scale model locomotives... The engine runs too fast at both full throttle (12 volts) and at minimum voltage (3 volts)... This is the same motor and gear assembly that Hallmark has in its SD40-2 and the RS-1 tests out pretty much the same. It's quiet, smooth runner. Unfortunately, it doesn't just creep away from a stop; instead, it lurches into motion... I don't know how many of these models Hallmark has imported; but if you really want an RS-1, here it is. I don't think you'll be disappointed. $140")