The AAR wheel arrangement system is a method of classifying locomotive (or unit) wheel arrangements that was developed by the Association of American Railroads. It is essentially a simplification of the European UIC classification, and it is widely used in North America to describe diesel and electric locomotives. It is not used for steam locomotives which use the Whyte notation instead.
The AAR system counts axles instead of wheels. Letters refer to powered axles, and numbers to unpowered (or idler) axles. "A" refers to one powered axle, "B" to two powered axles in a row, "C" to three powered axles in a row, and "D" to four powered axles in a row. "1" refers to one idler axle, and "2" to two idler axles in a row. A dash ("–") separates trucks, or wheel assemblies. A plus sign ("+") refers to articulation.
Read more about AAR Wheel Arrangement: 1A-A1, 1-D, 2-A1A, 2-B, 3-A1A, A1-1A, A1A-2, A1A-3, A1A-A1A, A1A-B+B, B, B-1, B-2, B-A1A, B-B, B-2-B, B-B-B, B+B+B, 2-B+B-2, 2-B+B+B+B-2, B+B-B+B, B-B+B-B, B-B-B-B, B-B+B-B+B-B, C, C-B, C-C, 1-C+C-1, 2-C+C-2, 2+C-C+2, 2-C1+2-C1-B, C-C+C-C, C+C-C+C, 1-D-1, 2-D-2, D-D, 2-D+D-2, B-D+D-B, 1B+D+D+B1, (B+B-B+B)+(B+B-B+B)
Famous quotes containing the words wheel and/or arrangement:
“The wheel of fortune guide you,
The boy with the bow beside you
Run aye in the way
Till the bird of day
And the luckier lot betide you.”
—Ben Jonson (1572–1637)
“The best protection parents can have against the nightmare of a daycare arrangement where someone might hurt their child is to choose a place that encourages parents to drop in at any time and that facilitates communication among parents using the program. If parents are free to drop in and if they exercise this right, it is not likely that adults in that place are behaving in ways that harm children.”
—Gwen Morgan (20th century)