AAR Wheel Arrangement - 2-B+B-2

2-B+B-2

"2-B+B-2" means there are two sets of articulated axles under the unit. Within each of these sets, there is a truck with two idler axles, and inboard of it are two powered axles. Two of these articulated sets are placed back to back and connected by a hinge. The PRR DD1 and DD2 electric locomotives used this arrangement.