class-58-bone

The BR Class 58 'Bone' was a series of 50 Co-Co diesel-electric heavy freight locomotives built by BREL Doncaster Works between 1983 and 1987, designed as a more modern and cost-efficient successor to the Class 56 for BR's heavy merry-go-round (MGR) coal and bulk freight traffic. The Class 58 was a significant departure from previous BR heavy freight practice in its modular construction — the locomotive body was built in bolt-together sections rather than welded as one unit, allowing easier access to components for maintenance and theoretically simplifying repair procedures. The Bone nickname derived from the class's raw, unfinished appearance compared with the more polished BR blue-era locomotives it succeeded.

The Class 58 used a Ruston Paxman 12RK3ACT engine producing 3,300 bhp, the same power output as the Class 55 Deltic but in a modern freight locomotive rather than an express passenger type, giving it adequate performance for the heavy coal trains from Yorkshire, Nottinghamshire, and Derbyshire pits to the power stations of the Midlands and South Yorkshire that represented the bulk of its work. The modular design in theory enabled better maintainability, but in practice the class's service record was mixed.

Two examples are preserved: 58016 and 58023.