The HXD2 is an electric locomotive and a series of related locomotive classes built by CNR Datong Electric Locomotive and Alstom. The locomotives designs are based on the Alstom Prima electric locomotives, and are a product of a cooperation agreement signed between the two companies in 2004. All locomotives are intended for heavy freight work, including coal trains on the Datong Qinhuangdao line.

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. They are equivalent to the B′B′ and Bo′Bo′ classifications in the UIC system. The arrangement of two, two-axled, bogies is a common wheel arrangement for modern electric and diesel locomotives.