British Rail Class 231

{{Short description|Diesel-electric multiple-unit passenger train}}

{{Use dmy dates|date=January 2019}}

{{Use British English|date=March 2017}}

{{Infobox train

| name = British Rail Class 231
FLIRT

| image = Class 231 Lisvane.jpg

| imagealt =

| imagesize =

| caption = Class 231 unit at {{stnlnk|Lisvane and Thornhill}} in 2023

| background = #AE0000

| interiorimage = Inside TfW 231008 (381008).JPG

| interiorimagealt =

| interiorcaption = Interior

| stocktype =

| service = 18 January 2023{{snd}}present{{cite tweet |author=Lee Waters MS |user=Amanwy |number=1615729461588017152 |date=18 January 2023 |title=All aboard! }}

| manufacturer = Stadler Rail

| assembly = Stadler Bussnang AG

| factory = {{ubli|indent=1em|Szolnok, Hungary
(bodyshells)|Bussnang, Switzerland
(final assembly)}}

| family = FLIRT

| replaced = {{ubl|{{brc|170}}|{{brc|769}}|{{brc|153}}|{{brc|150}}}}

| yearconstruction = 2021–2022

| yearservice =

| refurbishment =

| yearscrapped =

| numberconstruction =

| numberbuilt = 11

| numberservice = 11

| numberpreserved =

| numberscrapped =

| formation = 4 cars per unit:The Power Pack is technically a fifth vehicle, but as it contains no passenger accommodation it is excluded from the count of passenger cars.
{{abbr|DMS|Driver's cab, Motor car, Standard class saloon}}-{{abbr|TS|Trailer car, Standard class saloon}}-{{abbr|PP|Power Pack}}-{{abbr|TSW|Trailer car, Standard class saloon, Wheelchair accommodation}}-DMS{{cite letter |first=Steve |last=Fletcher |recipient=Anandarajah Mariadas (Stadler Bussnang AG)|subject=The Railways (Interoperability) Regulations 2011, as amended – Stadler Bussnang AG, Class 231/0 |date=27 June 2022 |url=https://www.orr.gov.uk/sites/default/files/2022-07/stadler-bussnang-ag-class-231-0-orr-authorisation-letter-2022-06-27-amended-annex.pdf |format=PDF |publisher=Office of Rail and Road |publication-place=London |access-date=1 October 2022 |archive-url=https://web.archive.org/web/20221001173755/https://www.orr.gov.uk/sites/default/files/2022-07/stadler-bussnang-ag-class-231-0-orr-authorisation-letter-2022-06-27-amended-annex.pdf |archive-date=1 October 2022 |url-status=live}}

| fleetnumbers = 231001–231011

| capacity = 170 seats, {{avoid wrap|plus 36 tip-up & 180 standees}}

| owner = SMBC Leasing{{cite magazine |title= Time to take stock as the 'bubble' bursts…|magazine=Rail Magazine |issue=989|date=9 August 2023 |pages=42–47}}

| operator = Transport for Wales Rail

| depots = Canton (Cardiff)

| lines =

| carbody = Aluminium

| trainlength = {{convert|80.7|m|ftin|abbr=on}}

| carlength =

| width = {{ubl|Passenger vehicles:
{{cvt|2.720|m}}|Power Pack:
{{cvt|2.822|m}}{{cite book |title=Bi-Mode Multiple Unit - FLIRT - Greater Anglia, UK |date=1 August 2019 |publisher=Stadler Rail Group |location=Bussnang |url=https://www.stadlerrail.com/media/pdf/feabmu0819_en.pdf |access-date=1 August 2019 |ref=755datasheet |id=FEABMU0819e |archive-url=https://web.archive.org/web/20231029170819/https://www.stadlerrail.com/media/pdf/feabmu0819_en.pdf |archive-date=29 October 2023 |url-status=live}}}}

| height = {{convert|3.915|m|ftin|abbr=on}}

| floorheight = {{convert|960|mm|ftin|abbr=on}}

| platformheight =

| entrylevelorstep =

| doors = Double-leaf sliding plug, {{avoid wrap|each {{cvt|1.300|m|ftin}} wide}}
(total 6 per side)

| art-sections =

| wheeldiameter = {{ubl|Powered: {{cvt|870|mm|in}}|Unpowered: {{cvt|760|mm|in}}}}

| wheelbase = Bogies: {{cvt|2.700|m|ftin}}

| maxspeed = {{convert|90|mph|km/h|0|abbr=on}}

| weight = {{convert|154.3|t}} (4-car set){{cite web |title = Class 231 |url = https://tfw.wales/sites/default/files/2022-09/CVLVC003%20Standard%20Form%20C%20-%20CVL%20IM%20Vehicle%20Change%20notice%20to%20consultees%20-%20TFWRL%20Class%20231.pdf |access-date = 11 December 2022 |website = Transport for Wales}}

| axleload =

| traction = IGBT

| engine = 4 × Deutz 16-litre V8 turbo-diesel

| poweroutput = {{convert|1500|kW|abbr=on}} at wheel

| tractiveeffort = Starting: {{convert|160|kN|lbf|abbr=on}}

| transmission =

| acceleration = {{convert|0.9|m/s2|mph/s|abbr=on}}

| deceleration =

| aux =

| powersupply =

| hvac =

| electricsystem =

| collectionmethod =

| uicclass = Bo′2′2′2′2′Bo′

| bogies =

| brakes =

| safety = {{ubl|AWS|TPWS|(plus provision for ETCS)}}

| coupling =

| multipleworking = Within class (max. 3 units)

| gauge = {{Track gauge|uksg|allk=on}}

| notes = Sourced from {{cite book |title=FLIRT Diesel-Electric Multiple Unit - Transport for Wales |date=1 April 2023 |publisher=Stadler Rail Group |location=Bussnang |id=FWBDMU0423e |url=https://www.stadlerrail.com/media/pdf/fwbdmu0423e.pdf |access-date=3 December 2020 |archive-url=https://web.archive.org/web/20231029171112/https://www.stadlerrail.com/media/pdf/fwbdmu0423e.pdf |archive-date=29 October 2023 |url-status=live}} unless otherwise noted.

}}

The British Rail Class 231{{cite tweet |author=Transport for Wales Rail |user=tfwrail |number=1201451920470228992 |date=2 December 2019 |title=The diesel-electric Metro trains that will run on the Maesteg, Ebbw Vale and Cardiff-Cheltenham lines from 2022 will be Class 231 }} is a class of eleven diesel-electric multiple units of the FLIRT family, which have been built for Transport for Wales by Swiss rolling stock manufacturer Stadler Rail. The first units entered service on 18 January 2023.