According to Hanks and Hodges, Dictionary of Surnames, Oxford University Press, 1988 - Rulon as we spell it doesn't exist.However from historical documents we see that the name was also spelt Rolland, Rouillion, Rollang and a many other ways.
Hanks and Hodges give Rolland and Rolland as variants of Rowland, which according to them comes from Rollant which mean in Norman "renown land."This is a spelling of the name Roland who was one of Charlemagne's most famous knights and as as result of his fame and bravery his name became a popular first name in England, France, Spain and Italy in the 9th-11 centuries AD.
Hanks and Hodges give a second origination as a place name in Debryshire and Sussex, England where is comes from the Old Norman worlds meaning "roebuck (or deer) woods."
Hope this helps. Heather Genealogy librarian Seattle Public Library and just beginning my Rulon line research