Overview

The British Rail Class 48 was a short-lived, experimental subclass of diesel locomotives produced in the mid-1960s. Only five examples were built at the Brush Falcon Works in Loughborough and delivered between 1965 and 1966. They were created alongside the larger Class 47 programme but were fitted with a different prime mover as a trial of an alternative Sulzer design.

Design and technical features

Externally the Class 48s matched their Class 47 siblings, sharing the same general body, bogies and control equipment. Their distinguishing feature was the Sulzer V12 12LVA24 power unit, a twelve-cylinder V engine rated at approximately 2,650 bhp (1,976 kW). This contrasted with the standard Sulzer 12LDA28C engine used in most Class 47s. The change aimed to explore potential improvements in power delivery, efficiency and maintenance requirements.

Service history and modifications

In regular service the five locomotives performed a variety of mixed-traffic duties, handling both passenger and freight workings. Operational experience revealed maintenance and compatibility advantages in standardising power units across a large fleet. As a result, the experimental 12LVA24 engines were removed in due course and replaced with the standard Sulzer units used by the wider Class 47 fleet; the locomotives were then assimilated into that class.

Importance and legacy

Although only a handful were built, the Class 48s are notable as an example of mid-20th-century experimentation with diesel traction during British Rail’s modernisation era. The subclass highlights the trade-offs railways face between technical innovation and the operational benefits of fleet commonality. For further technical background and historical context see resources on the wider Class 47 programme and the manufacturing works at Brush Falcon Works in Loughborough. Contemporary accounts of the engine type are available under the Sulzer designation 12LVA24, and archival entries about the subclass can be found via historical listings.

  • Built: 1965–66 at Brush Falcon Works
  • Number produced: five
  • Prime mover (original): Sulzer 12LVA24, ~2,650 bhp
  • Fate: re-engined and absorbed into the Class 47 fleet