This is a fairly obscure little item from Model Power. And although there is no indication (model or box) as to its origins, I think we all know Mehano crap when we see it. These were sold in sets of two (one powered and one dummy). Model Power variously referred to them as "Trolley Pair" or "Brill Trolley With Dummy". Further muddying the waters, an identical HO version (sold by AHM) was marketed as being a "Birney Trolley". So, your guess is as good as mine as far was what prototype (if any) they might have been based on. Listed in model railroading magazine ads for years and years, they ultimately vanished some time around 1998 (perhaps due to all the conflict in the former Yugoslavia?)
The main chassis is plastic, with an inner metal chassis holding the wheels and the gears. The motor in mine is a really cheap looking 3-pole affair (although I'm told that at least some of them came with 5-pole motors). All four wheels provide pickup, and all gearing is plastic. A non-directional headlight is wired to the chassis. The dummy chassis is exactly the same as the powered chassis, just sans the motor/worm assembly and the headlight. The wheel flanges are gigantic, so forget about running these on anything like Code-55 track. The drawbar is mounted to the chassis of the powered unit. There are no couplers (obviously).
Not surprisingly, performance on these is pretty awful. OK, let's say you've gotten ahold of a set that's aged well (IE, still runs). You'll find the powered unit to be a pretty quiet runner, and you'll probably be able to get the pair to run around a simple circle of track at full throttle without stalling. But beyond that, forget it. To make matters worse, I'm not even sure how one goes about taking these things apart in order to tune them. Once I removed the shell (just spread the sides and lift), I found a surprisingly complicated mechanism (especially for something so small, and so... Yugoslavian). And when it looked like I was going to have to completely disassemble the thing in order to get at the wheel-wipers, I decided enough was enough. I mean, seriously, what's the point?