British Rail Class 43 (HST)

The British Rail Class 43 (HST) is the TOPS classification used for the InterCity 125 High Speed Train (formerly Classes 253 and 254) diesel-electric power cars, built by British Rail Engineering Limited from 1975 to 1982, and in service in the UK since 1976.

The class is officially the fastest diesel locomotive in the world, with an absolute maximum speed of , and a regular service speed of . The record run was led by 43102 (43302) and trailed by 43159.

History and development Background

In the early 1970s, the British Railways Board made the decision to replace its main-line express diesel traction. Financial limitations were tight, so mass electrification was not possible. As a result, a new generation of high-speed diesel trains had to be developed.

Experience with the high-speed locomotives had shown that a low axle weight was essential to avoid damage to the track at sustained high speed, with sufficient power-to-weight ratio for a high speed train. Gas turbines had been considered as an alternative powerplant for the type but they were costly, were fuel hungry and also had high maintenance requirements and were thus ruled out in favour of a more conventional pair of diesel engines. To power the HST at up to , an arrangement of two medium-power diesel engines was opted for instead. It was not possible to position both engines within a single power car due to the low axle weight required, hence a pair of power cars, each equipped with a single engine, were used instead. The power car had a design weight limitation of 70 tonnes: to fulfil this required the use of lightweight equipment that still satisfied the necessary levels of strength, reliability, and reasonable affordability to accommodate the high planned utilisation rate for these vehicles; the 70-tonne weight of the power car achieved a 17.5-tonne axle loading.

It was designed by the British Railways Board Chief Mechanical & Electrical Engineer's Department at the Railway Technical Centre in Derby in collaboration with British Rail Research Division and various equipment manufacturers. Principal manufacture was performed by British Rail Engineering Limited (BREL); specifically, while the power cars were produced at Crewe Works, the accompanying trailer cars were built at Derby Litchurch Lane Works in Derby.

Prototype

To validate the design, a prototype set was produced. The engine used in the prototype power cars was the Paxman 'Valenta' 12RP200L, which developed . Despite being placed at opposing ends of the train, the two power cars were connected to one another via cables that ran the length of the train, permitting the leading cab to exercise effective control of both power cars. Each power car had a main driver's position at one aerodynamically shaped end with the other flat and gangwayed end having only an auxiliary driving position for shunting purposes.

The two prototype power cars emerged from Crewe Works in June and August 1972 and were initially numbered 41001 and 41002, but after a short period the entire set, including the passenger coaches, became reclassified as a diesel-electric multiple unit: British Rail Class 252. The power cars were given the coaching stock numbers 43000 and 43001. After proving trials on the Eastern Region the prototype High Speed Diesel Train (HSDT) was transferred to the Western Region, where it was deployed on PaddingtonBristolWeston-super-Mare services.

Production series

The design was successful and led to production orders being placed for similar trains for the Western, Eastern, Scottish and London Midland regions. The production power cars featured a redesigned front end without conventional buffers, although a rigid drawbar can be used to connect an HST to an ordinary locomotive. Following the introduction of production HST sets, the prototype unit was withdrawn, the power cars passing to the Research Division at Derby. Of the ten prototype coaches, two were adapted for use in the Royal Train, five were modified for use with the production HSTs, and three were transferred to Departmental stock.

The 197 power cars produced are numbered 43002-43198. 43001 was applied to the second of the two prototype power cars, while the first of the pair (now preserved at the NRM; formerly operational on the GCR) became 43000, which is unusual because BR TOPS classification numbered its locomotives from 001 upwards (this was because it was not, at the time, classified as a locomotive).

Buffered units

In 1987, as electrification of the East Coast Main Line was under way, British Rail realised that the new Mark 4 carriages for the and locomotives were not going to be finished in time for the introduction of electric services on the East Coast Main Line so, in late 1987, a total of eight Eastern Region power car conversions were carried out at the Derby Engineering Development Unit, whilst the other six were converted by the diesel repair shop at Stratford to have the lower valancing removed and buffers fitted.

After being fitted with buffers, these power cars began work as surrogate DVTs to work with the Class 91s and 89. The locomotives, working with conventional Mark 3 stock, worked on the line between 1987 and 1991, when the last Class 91 locomotives entered service. As well as buffers being fitted to these power cars, special remote control equipment was also added to the locomotives so they could be controlled by the locomotive at the front. Once these locomotives left DVT duties, the remote equipment was removed.

After privatisation, these power cars joined the Virgin Trains fleet working both Virgin CrossCountry and Virgin Trains West Coast routes, where they displaced loco-hauled stock. All the units were repainted from their original InterCity colours to the Virgin red livery. Later, Virgin Trains withdrew the HSTs when new and units were delivered, and nearly all of these power cars went into storage at Long Marston.

After years of storage, several of the power cars were bought by Midland Mainline to be part of Project Rio, special services running from to while major engineering works were undertaken on the West Coast Main Line. These units were kept in the de-branded Virgin Trains livery throughout their time with Midland Mainline and put back in storage once Project Rio had finished in 2006.

Two units joined Network Rail's New Measurement Train in 2003 and have continued to work with this service ever since. Both of these units have now had MTU engines fitted.

One unit was leased to GNER as a one-off power car, working as a spare unit that could be easily called for if an HST failed. For most of its time with GNER, it was based at Craigentinny yard in Edinburgh and was painted into GNER colours. This locomotive's lease ended in 2006 and it was returned to storage at Long Marston.

In 2007, Grand Central took an interest in the stored power cars and amalgamated them into its fleet of three HST sets. In total, six were bought by the company and ran high-speed services between Sunderland and London Kings Cross. Two were the final operational Paxman Valenta power cars, being re-engined in 2010 with the MTU treatment. While at the works being re-engined, Grand Central added the orange stripe that appears on its units, re-painted the front ends (making them look more like the non-buffered HSTs), and re-numbered the power cars into the four-hundreds. They were withdrawn from Grand Central service in 2017 after more Class 180s were acquired.

Engines

British Rail experimented with Mirrlees Blackstone MB190 engines in four Western region examples (43167–43170) between 1987 and 1996, but this experiment was unsuccessful and the standard Paxman Valenta engines re-installed.

Paxman began development of the Valenta's successor, the Paxman VP185, in 1987. The suggestion that British Rail participate in a trial of the new VP185 engine in the IC125 was first mooted in January 1991, and a formal agreement for the trial was signed in May 1993.

A qualifying requirement for the trial was that the engine should undergo a British Rail Type Test which was carried out between December 1993 and February 1994. The test involved completion of 3,000 cycles, each of 10 minutes duration, with four minutes at the maximum power of and six minutes at idle, simulating the typical 'on-off' nature of IC125 duty. The test was much more severe than operational duty, where the train operates at a maximum of . The successful results of the test cleared the way for installation of a VP185 in Power Car 43170 at Plymouth Laira Depot for in-service trials in the summer of 1994. Power car 43170 entered service on 22 September 1994. 43170 was given the nameplate "Edward Paxman".

During the late 1990s twenty-five HST power cars were re-engined with Paxman VP185 engines in order to improve fuel consumption and reduce emissions.

The last VP185 engine to be manufactured at Paxman's Colchester Works was despatched from the factory on 15 September 2003 as part of a programme to convert 14 Midland Mainline power cars to VP185 engines to supplement the four already converted during 1994/95, and this led to 43043/045/048-050/052/055/060/061/072/073/076/082 joining 43047/059/074/075 with this engine type.

Today there are no production power cars fitted with a Paxman Valenta engine, although the 125 Group have reinstalled a Paxman Valenta in the surviving prototype power car, 41001 (formerly 43000). The 125 Group are also in the process of reinstalling an operational Valenta into 43044, which has been given the nameplate Edward Paxman in commemoration.

Diesel-battery hybrid trial In 2007, Brush Traction and Hitachi equipped Paxman Valenta powered 43089 and a semi-permanently coupled Mark 3 coach with a diesel-battery hybrid power system for experimental trials. The power car was named "Hayabusa" (Hayabusa, はやぶさ, Japanese for Peregrine falcon, project name 'V-Train 2'). It returned to normal service with East Midlands Trains.

Design The body structure of the Class 43 comprises integral all welded, mild steel construction across both the underframe and the stressed skin bodyside. This structure was optimised using computer aided design and finite element analysis. Material thickness varies from across the majority of the underframe to on the bodyside frame pressings and for the bodyside skin. The body was internally divided by a pair of transverse bulkheads, one at the rear of the driver's cab and the other at the forward end of the luggage compartment; a self-draining sealing plate floor was installed between these bulkheads that collected any spillage within a tank located beneath the underframe. All of the air intakes are positioned as high as possible and fitted with disposable dry filters where deemed to be necessary. A secondary bulkhead separated the engine from the clear air compartment, in which the electrical apparatus, control and brake equipment were housed.