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:
“No great idea in its beginning can ever be within the law. How can it be within the law? The law is stationary. The law is fixed. The law is a chariot wheel which binds us all regardless of conditions or place or time.”
—Emma Goldman (1869–1940)
“There is no reason why parents who work hard at a job to support a family, who nurture children during the hours at home, and who have searched for and selected the best [daycare] arrangement possible for their children need to feel anxious and guilty. It almost seems as if our culture wants parents to experience these negative feelings.”
—Gwen Morgan (20th century)