I inherited an Omega from my great-great grandfather, that used to work as a train conductor. This watch has been in the basement for some years now, and I just recently found it. Would really appreciate it if someone could help me finding out a little more about it, and or tell me how this can be opened.

 

It looks like an old 18 size railway case, these usually had a back that unscrews, unfortunately it looks like it might be a swing out case. It there's no joint around the back half of the case that's likely the case.

If it is: First you pull out the crown. Then the front bezel unscrews, under the bezel, near the "six" there's a groove where you can insert your fingernail and lift the movement up, swinging it out of the case. You must be very careful that the crown disengages cleanly and not to damage the face. I hate this type of f***ing case and avoid them like the plague. If it looks like a swing out case take the watch to someone who has worked with them already and have him open the watch.

While they're not worth huge money, Omega watches of this era were, and if in decent shape and well serviced still are, very robust and reliable time pieces. Once open, post some pictures of the little brute's works and we'll see what we can find out about it.