In the Whyte notation for classifying the wheel arrangement of steam locomotives, an 0-8-8-0 is a locomotive with two sets of eight driving wheels and neither leading wheels nor trailing wheels. Two sets of driving wheels would give far too long a wheelbase to be mounted in a fixed locomotive frame, so all 0-8-8-0s have been articulated locomotives of the Mallet type, whether simple or compound. In the UIC classification, this arrangement would be, refined to Mallet locomotives, (D)D. The type was sometimes called Angus in North America.
Other equivalent classifications are:
UIC classification: DD (also known as German classification and Italian classification)
French classification: 040+040
Turkish classification: 44+44
Swiss classification: 4/4+4/4
The lack of leading and trailing wheels to assist the tracking and stability of the locomotive means that the 0-8-8-0 type is not suited to high speeds. The vast majority have seen use as very heavy switchers (generally for hump yard work), transfer locomotives for hauling cuts of cars between rail yards, or pushers for assistance on grades.
Most locomotives of this arrangement were built and served in North America, but there were exceptions. The Bavarian State Railways (K.Bay.St.B) built some 0-8-8-0T tank locomotives of class Gt 2x4/4, classified after unification of Germany's railway systems as class BR96. These worked trains over heavily graded stretches of line, and were the largest locomotives in Europe when introduced.
In 1915, the New York Central purchased an 0-8-8-0 numbered 2000 but proved to be very unreliable and also very costly to maintain as it jumped the rails quite often. Eventually in the 1930s, it was split into two locomotives, a useful 2-8-0 freight engine and a 0-8-0 switcher engine. The switcher engine got cut up and sold for scrap by 1950. The 2-8-0 freight engine maintained into service until NYC dieselization during the mid 1950's. The 2-8-0 and 0-8-0 locomotives that were from the 0-8-8-0 chassis locomotive do not exist anymore.
Used in Lionel O gauge only in Erie and Pennsylvania road names only.