Last year, Southern Pacific Co. took delivery of three 4000 hp diesel-hydraulic locomotive units built in Germany to meet the rigorous requirements of United States railroad service. These experimental units incorporate a propulsion system not currently available in the United States and represent the highest output diesel locomotive units yet constructed. The prototypes are being road tested in heavy duty mountain freight service and expedited freight service to develop their potential under operating conditions here. The paper covers fundamentals of diesel-hydraulic design, some interesting engineering features incorporated in these units, and the test program being conducted to develop the potentialities of this design under service conditions.
