mu guess is that this is one of the tens of thousands of cheap (yet heavy) Russian watches that have been infiltrating our shores for the past 15 years. they often have big trains or other decorations on back.
I believe you've got a watch equipped with a Molnija 3602 movement. Molnija watches are workhorses, and were among the better watches produced in the old USSR. Though I would guess that your watch dates to the 1960s or 1970s, Molnija is still in business, and movements like this are still in production. Some versions are used in some of the oversized wristwatches that are popular today. If you do a Google image search for Molnija, I think you'll find some pictures of your movement, with only minor details being different.
The stamping at the edge of the central brige says " 18 КАМНЙ", which is the Cyrillic for "18 jewels". The 3602 is an 18 jewel movement.
I concur with Gary that the watch is a Molnija, however they have gone out of business within the year or so. A shame because even though their recent movements are poorly finished, they are good inexpensive mechanical timekeepers.