Paxman Valenta

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Paxman Valenta
Paxman Valenta power unit with turbocharger and Brush Traction alternator fitted
ConfigurationV12 four-stroke turbo-charged & intercooled diesel
Displacement79 litres (4,800 cu in)
Fuel typeDiesel
Power output2,250 brake horsepower (1,680 kW) at 1,500 rpm
PredecessorPaxman Ventura
SuccessorPaxman VP185

The Paxman Valenta was an engine that was made by Paxman, Colchester for the High Speed Train, and is still in use in various marine applications, such as the Upholder/Victoria-class submarines.


Class 43 with Paxman Valenta engine at York

The Paxman Valenta was developed in the early 1970s for British Rail with the aim of using in both freight and passenger locomotives.[1] However the engine was only used in the two pre-production Class 41 and 195 production Class 43 powercars that were delivered to power High Speed Trains between 1975 and 1982.

The engine as originally fitted to the HSTs was designated 12RP200L and was a V12 four-stroke turbo-charged & intercooled diesel unit of 79 litres which developed 2,250 bhp at 1,500 rpm. The design of the Valenta was based on the Ventura which was fitted to the Class 29 diesel locomotives, amongst others. The engine is famous for the "Valenta Scream" on starting from rest, a distinctive high-pitched whine caused by the engine's turbocharger.[2][3] In 1977, the Valenta received the Queen's Awards for Enterprise.[4]

In 1985, four (43167-43170) were fitted with Mirrlees MB190 engines.[5] Beginning in 1995, a small number were fitted with Paxman VP185 engines, however the majority retained Valentas.[6]

In May 2005, First Great Western had Brush Traction fit two with MTU 16V4000 engines.[7][8] Judged a success, as part of a project to extend the lives of the HSTs, First Great Western decided to repower its entire fleet. GNER, CrossCountry, Network Rail and Grand Central also decided to repower their fleets with MTUs.[9][10] The only operator not to was East Midlands Trains, which opted to replace its Valentas with Paxman VP185s.[11]

Grand Central's 43084 and 43123 were the last two Valenta-engined powercars in service. They were taken out of traffic on 22 December 2010 for repowering with the latter named Valenta 1972-2010.


In May 2011, it was announced that the 125 Group would return prototype HST powercar 41001 to service. The powercar was at that time on static display at the National Railway Museum, York. It received a full overhaul, and was fitted with a reconditioned Paxman Valenta RP200L engine, number S508 installed new into Virgin CrossCountry's 43153 in 2001, before re-installation into First Great Western's 43143 after a spell in storage. It was one of about 10 engines that the 125 Group obtained.[12]

On 15 November 2014, 41001 hauled its first passenger train in preservation.[13]

Australian XPT[edit]

The engine was also fitted to the State Rail Authority's XPT, which was based on the HST power car design. Fourteen power car units were built in the 1980s by Commonwealth Engineering, Sydney followed by four by ABB Transportation, Melbourne in 1994. All were re-powered with VP185s in the early 2000s.[14][15]


  1. ^ "Paxman Valenta will power freight and passenger locomotives" Railway Gazette International October 1970 page 753
  2. ^ Roger Ford (1988). HSTs at Work. Ian Allan Publishing.
  3. ^ The Future of the Diesel Engine. Rail Safety & Standards Board.
  4. ^ "Suppliers" Railway Gazette International May 1977 page 171
  5. ^ "HSTs to have Mirrlees engines" Railway Gazette International December 1985 page 899
  6. ^ "Paxman wins order for seven 12VP185 engines" Rail Magazine issue 255 21 June 1995 page 9
  7. ^ "Life-extended Angel HST rolls out of Brush for £1.5m trial" Rail Magazine issue 514 25 May 2005
  8. ^ "Fitting the MTU power unit into the HSTs". 15 August 2008. Retrieved 27 February 2010.
  9. ^ "GNER confirms German built MTU engines for HST fleet rebuild" Rail Magazine issue 544 19 July 2006 page 12
  10. ^ "Brush wins XC Class 43 HST overhaul deal" Rail Magazine issue 586 27 February 2008 page 64
  11. ^ "East Midlands Trains goes for VP185s" Today's Railways issue 71 November 2007 page 58
  12. ^ Preservation Progress 125 Group 20 April 2008
  13. ^ 41001's Restoration & Introduction to Service 125 Group
  14. ^ Hollingsworth, Brian; Cook, Arthur (2000). "XPT Eight-car train". Modern Locomotives. p. 180. ISBN 0-86288-351-2.
  15. ^ "Market" Railway Gazette International April 2000 page 10