General Electric’s (GE) U25B diesel locomotive was the first of a series of four- and six-axle U-boats that helped the company make a name for itself. GE had been involved in diesel technology back to the pioneering Boxcab of the early 20th century, which is partnered with Alco and Ingersoll-Rand. GE served as a component supplier for years in an agreement with Alco for its line of early/first-generation diesel locomotives; that partnership dissolved in the early 1950s. GE began working toward its U-boat series with a cab unit/booster testbed set that worked on Erie and Union Pacific (UP). GE built ten UD18 four-axle units for Mexico’s NdeM (8000–8009) which had a somewhat similar appearance to the early production U25Bs. A pair of blue-and-while units (751 and 752) followed in the late 1950s and the first U25Bs came soon after.
Union Pacific was an early customer for GE’s U25B. The road owned 16 examples (625–640) of this first U-boat. The group included a mix of early production (high- and low-nose) U25Bs, some coming from GE demonstrator service. The group remained in service for UP from 1961-1962 through 1972 (with one roster member departing in 1970). The U25B lost to a wreck in 1970 (UP 627) and UP 632 (sold to Rock Island in 1972) are the only members of the fleet not to venture to Morrison-Knudsen and see rebuilding.
ABOVE: UP 627 and 625 sit in the snow at Council Bluffs, Iowa., waiting for their next run in early 1962. This roster member saw the shortest career among UP’s U25Bs with its life cut short following a wreck at Aiken, Kan., in 1968, then retired from the roster in 1970, and traded to GE in 1971. — R.R. Wallin photo/Kevin EuDaly collection