The Class 52 Westerns were among the most iconic of those early express passenger diesel locomotives, built to see off some of Britain’s mightiest steam engines, but at the same time making themselves a mighty legacy, even though their working lives were short indeed.
The origins of the Westerns date back to 1955, following the publishing of the Modernisation Plan to see off the fleet of hundreds of ageing steam locomotives that formed the backbone of the British Railways network. While the Eastern Region focused on the Class 55 Deltics, and the Midland invested in overhead electrics and the Class 81 to 85 AC electric locomotives, the Western Region, what was formerly the Great Western Railway’s domain, focused on diesel hydraulic traction as the way forward.
Diesel Hydraulic locomotives differ from the more conventional Diesel Electric locomotives in that they use multiple torque converters, in combination with gears and a mechanical drive, to convey power from the diesel engine to the wheels, whilst a diesel electric conveys power via an electrical DC generator that provides power to traction motors. The advantages of hydraulic traction, although this is an often argued point, is that it resulted in greater reliability, lower costs and lower weight.
Initial diesel hydraulic designs suffered from high inefficiency, being up to 65% less efficient that their diesel electric rivals. However, developments made in Germany, primarily on their V 200 locomotives of 1953, perfected the formula, and diesel hydraulic systems came into their own. The choice to use diesel hydraulic traction on the Western Region came down to the success of the V 200’s in Germany, which were seen to have the advantage of lighter weight, greater power/ratio and decreased track wear.
However, issues were quick to emerge when the technology was brought to the UK, largely due to government intervention (as always!). While the theory was very much sound in Germany, the UK government was reluctant to import V 200 locomotives (altered to a British loading gauge), as, at the time, the nation was politically against the idea of importing from Germany, especially so shortly after the war. As such, the technology would be handed over to British manufacturers and built in UK factories. This seems reasonable, but the main issue was that such technology was brand new to British builders, and thus reliability, power outputs and efficiency were very poor.
The first diesel hydraulic examples to be built in the UK were the Class 41 Warship and Class 22, both of which were built by the North British Locomotive Company in Glasgow. The issue of poorly made British versions of the German technology was compounded by the fact that NBL had very little experience when it came to building diesel locomotives. While they had garnered a strong reputation at building steam engines, the company’s first two outings, the 41 and 22, were incredibly poorly built, suffered high levels of unreliability and more often than not had to be rescued by the steam engines they were built to replace. These locomotives, built between 1959 and 1962, were all withdrawn by 1972 and scrapped.
Eventually, construction was handed over to Swindon Works, the former plant that built many of the Great Western’s legendary steam engines. In this instance, Swindon maintained much of the original German design, and thus output the highly successful Class 42 Warship locomotives, which entered service to greater success in 1958. Their German roots were not only plain on the outside, but internally as well, using two Maybach engines coupled to Mekydro hydraulic transmissions. Though the Warship, and the later built Class 35 Hymek, were much more successful, it was determined that a new fleet of much faster and more powerful locomotives were needed to operate the Western Region’s top expresses, ones that were in the hands of the mighty GWR King and Castle Class Steam Locomotives.
The design called for something similar to that of the Class 42, a comparatively streamlined body which was longer and still powered by Maybach engines, following their success in the Hymeks. The engines chosen were 1,350hp Maybach MD655 engines, but issues arose as to where to put the two powerplants within the locomotive. Originally, the engines were to be placed directly behind the driver’s cab, but it was found to be unbearably noisy. Although moving them more centrally was found to make the locomotive heavier, it did result in the locomotive being able to operate successfully on one engine in the event of a failure, where its diesel electric counterparts would struggle and need to be rescued by another engine.
The biggest problem however was between the transmission and the engine, where the top gear ratio for the transmission was too high for the torque characteristics of the engine, which meant the locomotive would struggle to reach its prescribed top speed of 90mph. This problem was especially prevalent for the routes these locomotives were to operate on, namely the Devon Banks between Exeter and Plymouth. While a Mekydro transmission would’ve been able to handle the power much better than the Voith transmission the Westerns would eventually operate with, it was not possible to create a Mekydro transmission that could fit inside British loading gauge.
Regardless, the Westerns entered service from 1961, with 74 locomotives built until 1964 between Swindon and Crewe Works. These, together with the Class 42’s and Class 35’s, helped to decimate the once extensive fleet of ex-GWR steam locomotives, the Westerns taking on high-profile express services to Bristol, Cardiff, Birmingham, Exeter, Plymouth and Penzance. Initially, the fleet was outshopped in a variety of colours which the Western Region used to make themselves stand out from the other parts of BR, these being either Maroon, Golden Ochre, Green or Desert Sand. All services the Westerns operated were out of London Paddington, but, in some instances, these trains ran out of London Marylebone, though these were rare and often due to diversions.
The top speed of the Westerns was 90mph, but this was only achievable on the flat or going downhill, as due to the power discrepancy with the transmission, the engines found it difficult to reach this speed while attempting to go uphill.
Nevertheless, the Western Region continued to maintain its autonomy against the other regions, with innovative new trains and top class expresses, including the precursor to the HST, the Class 251 and 261 Blue Pullman sets. However, this all seemed to fall down very quickly by the time the 1970’s arrived.
While the Western Region had prided itself on being different, the region’s ex-GWR management were gradually replaced by people more in tune with BR’s thinking, and quickly saw the disadvantages of having a non-standard, diesel hydraulic fleet of locomotives. In comparison to the 74 Westerns, there were 500 Class 47 diesel electrics, and they were comparatively expensive due to their inefficient nature, though they were undeniably reliable. As such, by 1972 it was decided that the diesel hydraulic locomotives would be phased out by the end of the decade.
While the troublesome Class 41 and 22 had disappeared by 1972, the Class 42’s (and their similarly built North British cousins the Class 43’s) were the next to go, disappearing the same year. This was followed by the Class 35 Hymeks in 1975, leaving only the Class 52 Westerns, now painted into the standard BR Blue. Seeing as these locomotives were on the way out, their external conditions were often very gaunt, with peeling paint and rust
In 1974, the first of the English Electric Class 50 locomotives were transferred to the Western Region from the Midland Region to replace the Westerns. These engines were originally built for London to Glasgow expresses, but following the electrification of the WCML north of Weaver Junction (near Runcorn), they were replaced in 1974 by Class 87 electrics. As such, these 50 locomotives were spare, and moved en masse to work services out of London Paddington and London Waterloo. Upon their introduction, Westerns were relegated to the on again/off again work of freight, and fleet numbers dwindled to the last 10 or so, all based at Laira depot in Plymouth. The final nail in their coffin was the introduction of the Class 43 HST sets in 1976, which brought about a new era of speed and comfort on the British Rail network. As such, 1977 would be these engine’s final hour, and by the end of the year nothing remained of the fleet, heralding the end of diesel hydraulic traction on BR rails.
Today, 7 members of the class are preserved across the UK network, and some have even made a return to the mainline. The Western is often considered among the more reliable preserved diesels, thanks largely to the excellent groups of volunteers and enthusiasts who keep these engines working. Such is the sturdy nature of these engines, that D1015 ‘Western Champion’ found itself put back on freight workings briefly during the mid-2000’s, while at the same time is a frequent operator of railtours up and down the nation. The Westerns may have only had a lifespan of 16 years, but they truly did leave an impression.