I recently had the opportunity to work on a Roskopf watch movement. These are interesting pieces in that they have three wheel trains instead of the usual four. What would normally be an idle wheel between the hour and minute wheels on the dial side is instead directly driven by being attached to the bottom an over-sized mainspring barrel. This attached pair of wheels slips somewhat to allow a pin/stem setting mechanism, on this watch. The cannon pinion slips completely freely on a fixed center shaft. The three-wheel train governs the motion with a pin-pallet escapement. There is no fourth wheel, and no second hand.
Although this style of movement was widely copied in the mid to late 1800s I believe this one to be an actual Roskopf. In addition to other indicative details, it is completely handmade.
After the application of every trick in the book, and the fabrication of a single new screw, it's actually running quite nicely.
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