Bo-Bo
B-B and Bo-Bo are the Association of American Railroads ( AAR ) and British classifications of wheel arrangement for railway locomotives with four axles in two individual bogies . 
<triplet> Bo-Bo <subj> wheel arrangement <obj> instance of <subj> railway locomotive <obj> subclass of <triplet> Association of American Railroads (AAR) <subj> wheel arrangement <obj> instance of