The Class 45, listed in a 1960 Ian Allan ABC as a Sulzer Type 4, was one of the diesel-electric classes that displaced steam on Britain’s principal express routes. Widely known as “Peaks”, these heavy 1Co-Co1 locomotives worked the Midland Main Line out of St Pancras and cross-country services for around two decades.
Design and build
A total of 127 locomotives were built between 1960 and 1962 at the British Railways works at Derby and Crewe. Each carried a Sulzer 12LDA28 engine of about 2,500 horsepower, driving through electric transmission. The 1Co-Co1 wheel arrangement, with a carrying axle at each end of the bogies, spread the considerable weight of the machine over the track.
In service
The Peaks became the mainstay of the Midland Main Line expresses from St Pancras and of long-distance cross-country services. They held that role for roughly two decades before newer types took over. Many of the class carried the names of British Army regiments.
Numbering
The locomotives were originally numbered D11 to D137. Under the TOPS scheme they were renumbered into the 45xxx series and became Class 45. The “Peak” name was shared with the related earlier Class 44, a pilot batch of ten named after mountains and fells, and with the later Class 46.
Withdrawal and preservation
The class was withdrawn by the late 1980s as more modern traction became available. Several examples were saved for preservation and can be seen on heritage railways. Their survival reflects the affection in which the Peaks were held by those who worked and travelled behind them.
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- Ian Allan ABC of British Railways Locomotives, Combined Volume, diesel section.
- Standard BR diesel class histories, for example the works of Colin J. Marsden.
- The Peak Locomotive Company, preservation group for the class.