Hi-Brd 4 | Self-Propelled Diesel-ElectricThe Self Propelled Hi Brd 4 ground power unit (GPU) is ideal for operations where there is not necessarily access to a tug, but still the need to walk the unit to the aircraft out on the ramp easily and with minimum difficulty. The unique self propelled feature makes the eco friendly 28 volt ground power unit easy to maneuver and can still be towed over longer distances.