Atlas's so called "Davenport Switcher" is actually a model of a German prototype (BR 237 001), but I guess Atlas figured that the Roco model looked enough like a Davenport to market it that way. Interestingly enough, a lot of them wound up being mislabeled as "Dewenport" switchers (evidently due to a screwup in the translation).
The chassis is all metal and relatively hefty -
The tiny motor is open-sided and has five poles with straight winding. All gearing is plastic. All three axles are geared. Only the outer four wheels provide pickup. There are no traction tires. A non-directional headlight is mounted to the front of the chassis. The Rapido-style couplers are chassis-mounted.
Big surprise, this model isn't much of a runner. The wheel flanges are ridiculously huge, making even Code-80 turnouts a hazard (and you can flat out forget about Code-55 entirely - turnouts or otherwise). And why they decided to make this thing an 0-4-0 in terms of pickup is beyond me. As is, it's a total stall machine. Like most early N scale switchers, what we have here is a loco that will run around a simple circle of track more or less reliably, but that's about it.
Circa 1982, Atlas discontinued this model along with the rest of their line of Roco-made locomotives (coinciding with their new partnership with Kato).
To remove the shell, simply unscrew the big ugly screw on top of the shell. It should lift right off at that point.
(Thanks for the motor pic, Claus)