Freon...Thank you for your comments.
I must modify my original "question," some, though. The contactor is a Honeywell 9425 R8243B1013; the RA117A, which I mistakenly listed, is a part of the oil burner circuit.
As I mentioned, the electric contribution is a design of my father's. Generally, I understand how it works, with the parts acting as you have mentioned.
My goal, though, is to obtain documents and schematics of these specific elements. Some, to better understand my dad's setup, and some to have good information in the case one or many of these devices might fail. Again, there seems to be little information about things because I presume they are no longer in current production. To date, I have not been able to get info from Honeywell or Essex (now Essex Brownell). Also, the "archive" sites don't seem to have anything listed, either.
I do hope someone might be able to point me to a source of documentation and or schematics. Surely, currnet products can replace these, but I'd like to have very good information so as to obtain a correct replacement.