the dv12 (sv12 and sr12 until 1977) is the standard finnish medium-weight diesel-hydraulic road switcher operated by vr. as all the main lines of finnish railway network have been electrificied, the locomotive is designated mostly to unelectrified, less frequently used side lines. occasionally it may still pull cargo trains on main lines. it has also been put in service as a shunter, replacing older classes dv15 and dv16 as they were retired. a total of 192 locomotives were built by lokomo and valmet between the years 1963 and 1984. as of 2019, the oldest dv12 units are 56 years old.