The HHP-8 is a double-ended electric locomotive manufactured by a consortium of Bombardier and Alstom. HHP-8 stands for High HorsePower 8000.
The HHP-8s replaced the GE E60s and supplemented the then-aging AEM-7s on Amtrak’s Northeast Corridor. However, some of the AEM-7s were upgraded to AEM-7ACs to match the hauling power of the HHP-8s.
The locomotives hauled Amfleet cars at speeds of up to 125 mph and were sometimes referred to by train crews as “Rhinos.” Maryland Rail Commuter (MARC) also operated HHP-8s on its Penn Line between Perryville and Washington, D.C.
Bombardier built 15 for Amtrak and six for MARC. Amtrak retired its final HHP-8 on November 7, 2014.
The locomotives are visually similar to Acela power cars, but they have noticeably shorter and stubbier noses. The HHP-8s had visible couplers and head-end power receptacles at both ends. Covers hide these on the front end of Acela power cars during normal operations.
During testing between 1999 and 2000, the locomotives experienced problems related to the differing power supply voltages used over the Northeast Corridor. They could switch between voltages automatically, but this feature malfunctioned in testing.
Cracking in the trucks was identified as a potential problem during testing. Safety officials at the time felt that possible crack development could be identified before failure with proper inspection.
In August 2002, HHP-8 locomotives were briefly removed from service after workers discovered the brackets that connected truck dampers (shocks) to the locomotive car bodies (“yaw dampers”) were cracking. The locomotives were returned to service after Amtrak instituted a program of frequent inspections. The damper brackets were redesigned, and the old brackets were replaced with the newer design.