Automatic Slow Speed Control for Locomotives

Special control apparatus has been developed and installed on four 2500-hp 6-motor locomotives to automatically maintain constant very low speeds for continuous loading of hopper cars in unit train service between coal mines and electric generating plants. Speeds can be controlled in the span of 1/8 to 8 mi/h in three ranges (1/8 to 1/2 mi/h, 1/2 to 2 mi/h, and 2 to 8 mi/h) with exact adjustment possible in any of the ranges. Manual operation by an on-board crew directed by radio from the loading location is now used. The special control apparatus presents the possibility of readily controlling train operation directly by radio from the loading location. The same locomotives are used in road service to haul the unit trains between mines and generating plants and may also be used for humping and weighing in-motion operations.