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Steam Locomotive

Wheel Arrangement Classifications

The following information and chart was copied from a page on the "Division Point" web site.

Chart created by : UNKNOWN

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STEAM LOCOMOTIVE WHEEL ARRANGEMENT CLASSIFICATIONS
Frederick Methvan Whyte's system of classification is used to describe the wheel arrangement of conventional steam locomotives.  In this system, the first number is the number of leading wheels, and the last is the number of trailing wheels.  The middle number (or numbers) give the number and arrangement of drivers.  A "T" added at the end indicates a tank engine.  Note that some railroads had their own particular "type" name.
Whyte Symbol	Wheel Arrangement	Type / Name
0-4-0	OO	4-wheel switcher, 4-coupled
0-6-0	OOO	6-wheel switcher, 6-coupled
0-8-0	OOOO	8-wheel switcher, 8-coupled
0-8-8-0	OOOO OOOO	Mallet (Articulated)
0-10-0	OOOOO	10-wheel switcher, 10-coupled
0-10-2	OOOOOo	Union (for Union RR, Pittsburgh)
2-2-0	oO	"Planet"
2-2-2	oOo	"Single"
2-4-2	oOOo	Columbia/Columbian (for New Zealand)
2-6-0	oOOO	Mogul
2-6-2	oOOOo	Prairie
2-6-4	oOOOoo	Adriatic (quite rare, none in U.S.)
0-6-6-0	OOO OOO	Mallet (Compound)
2-6-6-2	oOOO OOOo	Mallet (Articulated)
2-6-6-4	oOOO OOOoo	Mallet (Articulated)
2-6-6-6	oOOO OOOooo	Allegheny ("Blue Ridge" on the Virginian)
2-8-0	oOOOO	Consolidation
2-8-2	oOOOOo	Mikado (the "Mike"; called "MacArthur"s during WW2!)
2-8-4	oOOOOoo	Berkshire (also called "Kanawha" on the C&O, "Lima" on the B&M)
2-8-8-0	oOOOO OOOO	Angus, Mallet (Articulated)
2-8-8-2	oOOOO OOOOo	Mallet (Articulated) (Cab-Forward on SP, "Chesapeake" on C&O)
2-8-8-4	oOOOO OOOOoo	Yellowstone
2-8-8-8-2	oOOOO_OOOO_OOOOo	Triple Articulated, Triplex
2-8-8-8-4	oOOOO_OOOO_OOOOoo	Triple Articulated, Triplex (rear drivers under tender!)
2-10-0	oOOOOO	Decapod
2-10-2	oOOOOOo	Santa Fe (known as "Decapod" on the S.P., "Central" on the IC)
2-10-4	oOOOOOoo	Texas ("Colorado" on the Burlington!, "Selkirk" on the C.P.)
2-10-10-2	oOOOOO OOOOOo	Mallet (Articulated), Virginian
4-2-0	ooO	6-Wheeler, Jervis (Ca 1832!)
4-2-2_or_4-2-4	ooOo or ooOoo	Bicycle (some uncertainty here, more research needed)
4-4-0	ooOO	American, or Eight-Wheeler
4-4-2	ooOOo	Atlantic (known as "Chautauqua" by Brooks Loco Works and "Milwaukee" on Milwaukee Road)
4-4-4	ooOOoo	Reading (called "Jubilee" on the Central Pacific)
4-4-4-4	ooOO OOoo	4-cylinder Non-Articulated ("Duplex" on the Pennsy, "B&O" on B"O
4-4-6-2	ooOO OOOo	(two built for AT&SF)
4-4-6-4	ooOO OOOoo	4-cylinder Non-Articulated, "Duplex-Drive" for the Pennsy
4-6-0	ooOOO	10-Wheeler
4-6-2	ooOOOo	Pacific
4-6-4	ooOOOoo	Hudson ("Baltic" on the Milwaukee, "Shoreline" on the New Haven)
4-6-4-4	ooOOO OOo	4-cylinder Non-Articulated
4-6-6	ooOOOooo	Tank
4-6-6-2	ooOOO OOOo	Cab-Forward (S.P., 1911), 4-cylinder Articulated
4-6-6-4	ooOOO OOOoo	Challenger (U.P., 1936), 4-cylinder Articulated
4-8-0	ooOOOO	12-Wheeler, or "Mastodon" (C.P., 1882)
4-8-2	ooOOOOo	Mountain ("Mohawk" on the NYC)
4-8-4	ooOOOOoo	Northern (also known as Confederation, Dixie, Golden State, etc.,etc.)
4-8-8-2	ooOOOO OOOOo	Cab-Forward on S.P., 1928, Mallet (Articulated)
4-8-8-4	ooOOOO OOOOoo	Big Boy, Mallet (Articulated)
4-10-0	ooOOOOO	Mastodon (C.P., 1883)
4-10-2	ooOOOOOo	Southern Pacific ("Overland" on U.P.)
4-12-2	ooOOOOOOo	Union Pacific
6-2-0	oooO	Crampton (Camden & Amboy, 1849)
6-4-4-6	oooOO OOooo	Pennsylvania (PRR, 1939)

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