BR Class 52 “Western”

Built between 1961-1964, the BR Class 52 “Western” was a staple on the western region of British Railways. The Class 52 was a diesel-hydraulic type locomotive powered by two Maybach prime movers tied to a Voith hydraulic transmission. The Class 52 was a vital asset in the western region, as it was the regions most powerful locomotive, and hauled some of the regions premier passenger trains. The locomotive experienced somewhat of a short lifespan however, as many factors, including the implementation of the High Speed Train (HST) displaced many members of the fleet, before finally being retired in the late seventies. 

Background

During British Rail’s modernisation plan, the agency’s board recognised the success and economy of Germany’s diesel-hydraulic locomotives. During modernisation, there were constant political pressures on the various regions of British Rail to implement diesel power into their fleets. This led to numerous non-standard diesel designs, and oftentimes, no prototype of which to test these designs. Many regions of BR implemented diesel-electric power into their fleets, while the western region volunteered to experiment with diesel-hydraulic locomotives.

Many diesel-hydraulic designs were manufactured before the Class 52s, including the Class 22″baby warship”, the Class 35 “Hymek”, and Class 42 and 43 “Warship”, these locomotives, although effective, were mass produced with little knowledge about performance, due to the pressure on the agency to modernise. However, these locomotives did not sustain the power of their diesel-electric counterparts, and added horsepower was needed for certain services in the western region. Thus, a higher horsepower locomotive was needed, especially for the western region expresses. It was difficult for management to find a locomotive design to suit their needs, as many hydraulic transmissions at this time could only handle 1,500 horsepower. It was then decided to place two prime movers into the Class 52, similar to the warship class, however, an updated Bristol-Siddeley Maybach prime mover was used. This would prove innovative, as if one of the prime movers failed, one could be used for power, which prevented many service interruptions.

Diesel-hydraulic power was attractive to British Rail because of its lightweight design, which was easier on the railway infrastructure, and led British Rail to believe that maintenance costs would decrease. However, the Class 52 and similar locomotives were not as powerful as there diesel-electric counterparts. Additionally, due to the hydraulic transmission, increased fuel consumption was prevalent.

The Class 52 was constructed at the western region’s Swindon Works, which was also responsible for maintenance of the fleet. During construction, British Rail was experimenting with different liveries, which resulted in the Westerns being quite the colorful fleet, with the class leader D1000 being painted in “desert sand” livery, while others were painted green and red, and eventually, some of the fleet was painted into BR blue when implemented.

The Class 52 design flaws caused the premature retirement of the class, in favour of the Class 25, 46,and 47 locomotives. This, along with the electrification of the West Coast Main Line (WCML), resulted in a copious amount of Class 50s being made available,additionally, the implementation of the HST saw many members of the fleet withdrawn and allocated to Plymouth for secondary services until eventual retirement.

Technical

The Class 52 was built with two 1,350 horsepower Maybach MD655 prime movers, linked to a Voith hydraulic transmission. When constructing the Class 52, it was discovered that the Maybach prime mover in the Class 35 “Hymek”, linked to a Mekydro transmission was superior to the North British Locomotive Works and earlier Maybach prime mover in the “Warship”class, thus a more powerful Maybach prime mover was chosen for the western class. The westerns were given the Voith transmission instead of the Mekydro because a Mekydro transmission designed for the horsepower capable of the westerns was not feasible for the British loading gauge.

Initially, the twin engines were slated to be located behind the cabs, however, complaints from drivers constituting increased noise resulted in moving the prime movers towards the center of the locomotive, increasing the overall weight of the locomotives, hindering the lightweight design. Another major flaw was the lack of electric train heating (ETH), resulting in the lack of hotel needs for the carriages.  Additionally,the locomotive, capable of 90mph, oftentimes struggled to gain speed, as the torque of the Maybach prime mover did not coincide with the high gearing of the transmission, which resulted in reduced acceleration and efficiency.

Many westerns were not as powerful when considering drawbar horsepower, as their diesel-electric counterparts outperformed the hydraulics.  At the drawbar, the westerns performed similarly to the warship class, even though the prime mover was more powerful. The westerns had about 56% of the power being distributed to the flywheel, while its diesel electric counterparts were receiving 80% of the power.

In the early seventies, many westerns were equipped with air brakes in addition to their vacuum braking systems, which extended the life of the class significantly. However, D1017-D1020, did not receive air brakes, and were the first of the class to enter retirement.

Preservation

Today, seven example of the class are in preservation, (D1010, D1013, D1015, D1023, D1041, D1048, and D1062). These are owned and operated by various heritage railways and museums, including the National Railway Museum, the Severn Valley Railway, the East Lancashire Railway, the Midland Railway, and the West Somerset Railway. D1015 is mainline certified, and is operated on various enthusiast rail tours.

Western Names

Technical

For further information on the history of British diesels, Greg Morse’s book “British Diesel Locomotives of the 1950’s and 60’s” takes an in depth look at the history of early dieselisation. (Link to Amazon)