class-24-sulzer

The BR Class 24 was a series of 151 Bo-Bo diesel-electric mixed-traffic locomotives built by British Railways Derby Works between 1958 and 1961, using a Sulzer 6LDA28 six-cylinder in-line diesel engine and Crompton Parkinson or Brush electrical equipment to produce a general-purpose locomotive intended for the wide variety of mixed-traffic duties on BR's network — freight, secondary passenger, parcels, and engineers' trains — that required more power than the light shunters could provide but didn't justify the larger Type 4 main-line locomotives. The Class 24 was the forerunner of the closely related Class 25, which used the same Sulzer engine but with improvements that gave better reliability and performance.

The Sulzer 6LDA28 engine at the heart of the Class 24 was a well-proven Swiss diesel of straightforward six-cylinder in-line configuration, giving the locomotive a solid mechanical foundation compared with some of the more exotic engine choices of the Modernisation Plan era. Sulzer diesel engines had a long history of reliable railway traction service in continental Europe, and the Derby-Sulzer partnership that produced the Class 24 — and its successor the Class 25 — was one of the more successful of the Modernisation Plan procurement decisions. The locomotive was nevertheless somewhat under-powered for its Type 2 classification, and the Class 25 with its 1,250 bhp Sulzer 6LDA28-B engine was the improved replacement that addressed the Class 24's modest performance.

Four Class 24 locomotives are preserved: 24061, 24081, D5032, and D5054.