Class 43

The British Rail **Class 43 (HST)** is the TOPS classification used for the InterCity 125 *High Speed Train* (formerly classes 253 and 254) 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 148 mph (238 km/h), and a regular service speed of 125 mph (201 km/h). The record run was led by 43102 and trailed by 43159.[1][2][3]

## History and 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 Class 55 *Deltic* locomotives had shown that a low axle weight was essential to avoid damage to the track at sustained high speed, and that high-speed engines were the only way to provide a good enough power-to-weight ratio for diesels. To power the HST at up to 125 mph (201 km/h), each power car had a new diesel engine, the 12-cylinder Paxman Valenta, running at 1,500 rpm and developing 2,250 bhp (1,680 kW). The 70-tonne weight of the power car gave it a 17.5-tonne (per-)axle loading.

## Development and design

### Prototype

The prototype set was developed at the Railway Technical Centre, Derby, the power cars having been constructed by British Rail Engineering Limited's (BREL) Crewe Works and the British Rail Mark 3 passenger cars by BREL's Derby Litchurch Lane Works. The engine used in the prototype power cars was the Paxman 'Valenta' 12RP200L, which developed 2,250 horsepower (1,680 kW). The electrical equipment was supplied by Brush. The power cars 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 the 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 Paddington Bristol/Weston-super-Mare services.

In May 2011 the National Railway Museum (NRM) announced that the remaining HST prototype power car 41001 would undergo full restoration work.[4] A long-term loan was agreed between the NRM and the 125 Group of volunteers for the locomotive and a Paxman Valenta RP200L engine. The replacement engine (no. S508) was required as the original Valenta engine (no. S183) had been sectioned for display purposes. The S508 engine was lifted into the locomotive at Neville Hill TMD on 29 June 2012.[5]

In order to facilitate a main line move, Class 41 prototype HST power car 41001 was re-registered as a Class 43/9 locomotive, with the number 43000. It is the only locomotive in this sub-class.[6]

### 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,[7] five were modified for use with the production HSTs,[8] and three were transferred to Departmental stock.[9]

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 and operational at the Great Central Railway (Nottingham)) 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 Class 89 and Class 91 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 cars (Numbers 43013/014/065/067/068/080/084/123) conversions (on 43014/123) were carried out at the Derby Engineering Development Unit, whilst the other six (43013/065/067/068/080/084) 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 Mk3 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 powercars, 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 Class 220 and 221 units were delivered, and nearly all of these power cars went into storage at Long Marston.

After years of storage, several of the powercars were bought by Midland Mainline to be part of Project Rio, special services running from London St Pancras to Manchester 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.

43013 and 43014 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.

43080 was leased to GNER as a one-off powercar, working as a spare unit that could be easily called for if a 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, 43065/067/068/080/084/123 were bought by the company and now run high-speed services between Sunderland and London Kings Cross. HSTs 43084 and 43123 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 Class 180 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. These are the current numbers: 43465 (065)/467 (067)/468 (068)/480 (080)/484 (084)/423 (123).

### 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. These four locomotives have since all been re-engined with the MTU 16V4000 engines. 43167 is now 43367 and operates with London North Eastern Railway, whilst 43168-43170 are still in service, in the former Western region area under Great Western Railway

Paxman began development of the Valenta's successor, the 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.[10]

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.[10] The test involved completion of 3,000 cycles, each of 10 minutes duration, with four minutes at the maximum power of 2,611 kW (3,501 bhp) 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 1,678 kW (2,250 bhp). 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.[10] 43170 was given the nameplate "Edward Paxman".[*clarification needed*][11]

During the late 1990s twenty-five HST power cars were re-engined with Paxman 12VP185L engines in order to improve fuel consumption and reduce emissions.

The very last VP185 engine to be manufactured at Paxman's Colchester Works was despatched from the factory on 15 September 2003 as part of a program 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.[12]

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 powercar, 41001 (formerly 43000).

### 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').[13][14][15] It has since been returned to normal service with East Midlands Railway.