View source for British Rail Class 15

{{Short description|Diesel Electric locomotive designed by British Thompson-Houston}}
{{Use dmy dates|date=December 2024}}
{{Use British English|date=November 2013}}

{{Infobox locomotive
|name = BTH Type 1<br>British Rail Class 15
|powertype = Diesel-electric
|image = British Thomson Houston Type 1 D8208 (8315658288).jpg
|caption = A BTH Type 1 (later Class 15) at Stratford MPD in July 1966
|fleetnumbers = D8200–D8243
|totalproduction = 44
|builder = [[British Thomson-Houston]] at [[Yorkshire Engine Company]] (Initial Batch) <br> [[British Thomson-Houston]] at [[Clayton Equipment Company]] (Second Batch)
|builddate = 1957–1961
|gauge = {{track gauge|ussg|allk=on}}
|primemover = [[Paxman (engines)|Paxman]] 16YHXL<ref>{{cite web | url=http://www.railblue.com/Class%20Headers%20v2.0/class_15V.2.htm | title=Class 15 | work=Rail Blue | access-date=1 January 2014 | archive-date=4 September 2014 | archive-url=https://web.archive.org/web/20140904005008/http://www.railblue.com/Class%20Headers%20v2.0/class_15V.2.htm | url-status=dead }}</ref>
|transmission = [[Diesel-electric transmission|Diesel electric]]
|Britishclass= Bo-Bo
|uicclass = [[Bo′Bo′]]
|wheeldiameter = {{convert|3|ft|3+1/2|in|m|abbr=on}}
|minimumcurve = {{convert|3.5|chain|m|2|lk=in}}
|trainbrakes = [[Vacuum brake|Vacuum]]
|locobrakeforce = {{convert|31|LTf|kN|abbr=on|lk=in}}
|wheelbase = {{convert|31|ft|0|in|m|abbr=on}}
|length    = {{convert|42|ft|0|in|m|abbr=on}}
|width     = {{convert|9|ft|2|in|m|3|abbr=on}}  
|height    = {{convert|12|ft|6|in|m|3|abbr=on}}
|locoweight= {{convert|69|LT|t ST|lk=in}}
|maxspeed  = {{convert|60|mph|abbr=on}}
|poweroutput = ''Engine:'' {{convert|800|hp|0|abbr=on|lk=on}}<br>''At rail:'' {{convert|627|hp|abbr=on}}
|tractiveeffort = ''Maximum:'' {{convert|37500|lbf|kN|abbr=on|lk=in}}
|fuelcap = {{convert|400|impgal|L USgal|abbr=on}}
|trainheating =
|multipleworking = <span style="color:blue;">★</span> Blue Star
|axleloadclass = [[Route availability|RA]] 4
|operator = [[British Railways]]
|retiredate = 1968–1971<ref>{{cite web | url=http://www.railblue.com/Fleet/class_15_fleet.htm | title=The Class 15 Fleet | work=Rail Blue | access-date=1 January 2014 | archive-date=5 September 2014 | archive-url=https://web.archive.org/web/20140905031026/http://www.railblue.com/Fleet/class_15_fleet.htm | url-status=dead }}</ref>
|disposition = 1 preserved, remainder scrapped
| displacement     = {{convert|78.4|L|cuin|abbr=on}}
| alternator       =
| generator        = ''Main'' : BTH RTB10858<br>''Auxiliary'' : BTH RTB7420
| tractionmotors   =  4 x BTH 137BZ, nose suspended, with single reduction gear
| cylindercount    = 16
| cylindersize     = [[Bore (engine)|bore]]: {{convert|7|in|mm|0|abbr=on}} <br /> [[Stroke (engine)|stroke]]: {{convert|7+3/4|in|mm|0|abbr=on}}

}}
The '''British Rail Class 15''' [[diesel locomotive]]s, also known as the '''BTH Type 1''', were designed by [[British Thomson-Houston]], and built by the [[Yorkshire Engine Company]] and the [[Clayton Equipment Company]], between 1957 and 1961. They were numbered D8200-D8243.<ref>{{cite web |url = http://www.brdatabase.info/locoqry.php?action=class&type=D&id=15 |title = Yorkshire Eng Co & BTH Ltd 15 Bo-Bo |publisher = brdatabase.info |access-date = 7 December 2020}}</ref>

The Class 15 was ordered by [[British Railways]] (BR) shortly after the announcement of the [[1955 Modernisation Plan]], which led to the procurement of a diverse number of [[diesel locomotive]]s under the 'pilot scheme'. Shortly following the completion of the first locomotive during 1957, its performance was sufficient to justify multiple follow-on orders, leading to a total fleet of 44 locomotives. In service, the type was relatively unreliable, much of this been traceable to its [[Paxman (engines)|Paxman]] 16YHXL power unit. Its fortunes were further impacted by inconsistent policy making. During the late 1960s, it was decided to withdraw the Class 15 in favour of the more numerous and successful [[British Rail Class 20]] locomotive, both types having been developed to satisfy the same Type 1 specification. Their final use was as departmental vehicles, coming to an end in the late 1980s. One example has survived into preservation.

== Background ==
In less than a decade following the formation of [[British Railways]] (BR), substantial changes were being made. Under the [[1955 Modernisation Plan]], a long-term strategy of replacing [[steam locomotive]]s with a combination of [[diesel locomotive]]s and [[electric locomotive]]s was adopted, with the former being largely intended as an interim measure for most areas ahead of widespread [[railway electrification|electrification of trunk routes]]. There was also a strong political desire to support British manufacturers in transitioning towards the design and production of these favoured forms of traction. Due to a lack of expertise, this often involved the pairing of traditional locomotive manufacturers with various firms within the electrical sector, even though the latter typically had very limited experience of the railways.<ref name = "bradley tws"/>

In accordance with these policies, BR ramped up its efforts to convert its fleet, placing numerous orders within a short timeframe for diesel locomotives to several different specifications with various manufactures.<ref name = "bradley tws"/> It placed four separate lots of orders, for a cumulative 44 ''BTH Type 1'' diesel locomotives with the heavy engineering company [[British Thomson-Houston]] (BTH). The first batch of locomotives was primarily intended for evaluation purposes, this initiative coming under the remit of BR's pilot scheme.<ref name = "bradley tws"/>

==Construction==
While BTH was appointed as the main contractor and was viewed as being capable of designing the type, the company lacked capacity at its facility in [[Rugby, Warwickshire]], and thus was unable to produce the locomotives inhouse. The practical resolution to this was to [[subcontract]] both the design and manufacture of the mechanical elements (e.g. running gear, bogies, bodies) to other firms, primarily the [[Yorkshire Engine Company]] and the [[Clayton Equipment Company]], neither of which had any experience with main line diesel locomotives.<ref name = "bradley tws"/>

Accordingly, the design and manufacture of the type was a collaborative effort between these companies.<ref name = "bradley tws"/> Specifically, while BTH supplied the majority of the electrical equipment, [[Paxman (engines)|Paxman]] supplied the power units, Clayton supplied the bogies and superstructure, construction of the frame and final assembly occurred at Yorkshire Engine's [[Sheffield]] works, for the initial batch of ten locomotives. However, final assembly was transferred to Clayton for all subsequent batches.<ref name = "bradley tws"/>

The design of the locomotive was in conformance with the stated requirements listed in the 'Type 1' specification. As such, this led to the inclusion of numerous features such as provisions for operating in multiple with other members of the type.<ref name = "bradley tws"/> The propulsion system consisted of a single Paxman 16YHXL engine that provided up to {{convert|800|hp|0|abbr=on|lk=on}} that, via a [[diesel-electric transmission]], drove four individual [[Direct current|DC]] [[traction motor]]s. In comparison with a typical locomotive, the design featured a relatively high-speed engine for the era.<ref name = "bradley tws"/>

During late 1957, the first example of the type emerged.<ref name = "bradley tws"/> Furthermore, the type was envisioned for serving various types of smaller trains on secondary routes, such as the haulage of local freight and empty coaching stock trains. However, the fortunes of the class were somewhat impacted by the pilot scheme being abruptly terminated amid persistent budgetary shortages.<ref name = "bradley tws"/>

The performance of the initial batch of 10 locomotives quickly showed the design held promise, leading to repeat orders for 34 more locomotives to be placed soon after their entry into service. These locomotives, numbered D8210–D8243, were constructed at Clayton's facility in [[Hatton, Derbyshire]], were delivered between October 1959 and February 1961.

==Operations==
===Introduction===
[[File:East Finchley Station, with Diesel on local goods geograph-2398832-by-Ben-Brooksbank.jpg|thumb|left|D8241 at East Finchley with local goods train, 1962]]
{| class="wikitable floatright"
|+Distribution of locomotives,<br>October 1967<ref>{{cite book
  |title=British Rail Locoshed Book
  |year=1968
  |publisher=[[Ian Allan Publishing|Ian Allan]]  |location=Shepperton 
  |isbn=0-7110-0004-2
  |page=31
}}</ref>
|-
|colspan=3 |{{Location map+ |England south|width=220 |caption= |places=
 {{Location map~|England south|lat_deg=51.5455 |lon_deg=-0.0060 |label=30A |link=Stratford TMD |marksize=16 |position=bottom |mark=blue 00ffff pog.svg }}
 {{Location map~|England south|lat_deg=52.0451 |lon_deg=1.1524 |label=32B |link=Ipswich engine shed |marksize=12 |position=top }}
 {{Location map~|England south|lat_deg=51.5582 |lon_deg=-0.1099 |label=34G |link=Finsbury Park TMD |marksize=7 |position=left }}
}}
|-
!Code ||Name ||Quantity
|-
|style="text-align:center" |30A ||[[Stratford TMD|Stratford]] ||style="text-align:right" |28
|-
|style="text-align:center" |32B ||[[Ipswich engine shed|Ipswich]] ||style="text-align:right" |12
|-
|style="text-align:center" |34G ||[[Finsbury Park TMD|Finsbury Park]] ||style="text-align:right" |4
|-
!colspan=2 scope=row |Total:
|style="text-align:right" |44
|}
The first ten locomotives were delivered to the [[London Midland Region of British Railways|London Midland Region's]] [[Devons Road#Motive power depots|Devons Road depot]] in [[Bow, London|Bow, East London]],<ref>{{cite magazine|title=The BTH Type 1|first=Evan|last=Green-Hughes|magazine=Hornby Magazine|pages=74–77|issue=35|date=May 2010|location=Hersham|publisher=Ian Allan Publishing|issn=1753-2469|oclc=226087101}}</ref> where they were evaluated against the contemporary [[British Rail Class 16|North British Type 1 (class 16)]] and [[British Rail Class 20|English Electric Type 1 (class 20)]] designs. Soon, however, the entire class was allocated to depots on the [[Eastern Region of British Railways|Eastern Region]], where they remained until withdrawal. The second block of ten was originally allocated to [[March, Cambridgeshire|March]] depot in [[East Anglia]], however due to the [[Clean Air Act 1956]] the locomotives were quickly re-allocated to East London, allowing the replacement of steam locomotives in that area. Thereafter, the type was allocated exclusively to [[Stratford TMD|Stratford]], [[Finsbury Park TMD|Finsbury Park]] and [[Ipswich engine shed|Ipswich]] depots.

Class 15s were generally used on freight and infrastructure operations, and haulage of passenger trains was limited to replacement as a result of failure. An example of such an occurrence was on the northbound [[Fenman]] on 6 January 1961 where D8236 hauled the train, including the failed [[British Rail Class 31|Class 31]] D5665, from near [[Stanstead Abbotts|Stanstead]] to {{stn|Bishop's Stortford}} where a more powerful replacement took over.<ref>{{cite magazine| author = <!--Staff writer(s); no by-line.--> | title = Motive Power Miscellany| magazine = Trains Illustrated| location = Hampton Court| publisher = Ian Allan| date = March 1961| volume = XIV | issue = 150 | page = 182}}</ref>

A member of the class also worked as the train ferry shunter at Harwich Town during the 1960s<ref>{{cite journal |last1=Graham |first1=Hardinge |title=Rail Report |journal=Ipswich Transport Journal |date=September 1972 |volume=92 |page=33}}</ref> and for a period a Class 15 operated as the [[Switcher#Station pilot|station pilot]] at [[Liverpool Street station]], the last locomotive used being 8234 which was replaced by a [[British Rail class 08|Class 08]] on 4 October 1971.<ref>{{cite magazine| author =<!--Staff writer(s); no by-line.--> | title = Motive power miscellany| magazine = Railway World| location = Shepperton| publisher = Ian Allan| publication-date = December 1971| volume = 32| issue = 379| page = 554}}</ref>

===Problems and impact===
The Class 15 was troubled by its relatively high level of unreliability, which was largely centred around the type's Paxman engine; as delivered, the engine was found to require excessive maintenance.<ref name = "bradley tws"/> A series of modifications to the pistons, piston rings and maintenance schedules, and fitting cast iron cylinder heads led to considerable improvements in the engine's reliability, however, it remained a complex V16 for only providing 800&nbsp;bhp, while the small size of the class bore poorly at a time when the rail network was rapidly contracting. Furthermore, the layout of the locomotive, which positioned its single cab part-way down the body akin to a North American [[Road switcher|road-switcher]], provided the crew with a relatively poor forward visibility in both directions of travel, although this was initially tolerated as it was no worse than the visibility offered by the cab of a steam locomotive.<ref name = "bradley tws"/>

According to railway author Rodger Bradley, the shortcomings of the Class 15 were not so much attributable to its designers but largely came as a consequence of ill-defined requirements, which can be largely attributed back to moving government policies.<ref name = "bradley tws"/> Additional factors highlighted by Bradley include a general dependence upon the wider British electrical industry to both design and deliver numerous subsystems that would function sufficiently well upon the often-challenging railway environment, along with radical changes to the national economy during this era had also impacted the type's suitability to these broader circumstances and thus its overall performance.<ref name = "bradley tws">{{cite web |url = https://twsmedia.co.uk/bth-type-1-bo-bo-happy-60th-birthday/ |title = BTH Type 1 Bo-Bo – Happy 60th Birthday |publisher = twsmedia.co.uk |first = Rodger |last = Bradley |date = 11 January 2018 |access-date = 7 December 2020 |archive-date = 2 December 2020 |archive-url = https://web.archive.org/web/20201202210433/https://twsmedia.co.uk/bth-type-1-bo-bo-happy-60th-birthday/ |url-status = dead }}</ref> Despite these various issues, the Class 15 can be considered to be more successful than several contemporary Type 1 locomotives, such as the [[British Rail Class 16|Class 16]] and the later [[British Rail Class 17|Class 17]].{{Citation needed|date=December 2020}}

===Accidents and incidents===
On 21 November 1963, locomotive No. D8221 crashed through buffers whilst shunting at [[Ipswich engine shed]] and ended up across Croft Street. After attempts to tow it back onto the track using diesel locomotives failed, it was retrieved using the only [[steam locomotive]] in service at Ipswich, which had been retained for carriage heating purposes.<ref name=Earnshaw5>{{cite book |last=Earnshaw |first=Alan |title=Trains in Trouble: Vol. 5 |year=1989 |publisher=Atlantic Books |location=Penryn |isbn=0-906899-35-4 |page=43 }}</ref>

===Withdrawal===
Following a persistent decline in freight duties in the London area, in combination with the type being a relatively small and unsuccessful non-standard class, the type was considered to be surplus to requirements by the late 1960s. The ubiquitous [[British Rail Class 20]], which had been developed to meet the same Type 1 specification, was more numerous and had proved to be less troublesome to operate, thus it effectively replaced the type in all operational respects.<ref name = "bradley tws"/> The type was speedily removed from traffic, being withdrawn from capital stock between April 1968 and March 1971.<ref>{{cite web |title=Class 15 history |url=http://www.d8233.org.uk/history.htm |publisher=Class 15 Preservation Society |access-date=21 December 2018}}</ref> D8225 was observed operating at Temple Mills as late as 28 March 1971.

After withdrawal 23 of the class were stored at the former [[Ipswich engine shed]] during 1971 before being hauled away, generally as part of booked freight trains, for scrapping.<ref>{{cite journal |last1=Hardinge |first1=Graham |title=The Great Eastern in 1971-part 1 |journal=Ipswich Transport Journal |date=January 1972 |volume=88 |page=10}}</ref>

==Conversion==
[[File:Colchester MPD Diesel Class 15 (D8233) BTH Diesel ADB968001.jpg|thumb|ADB968001 (ex D8233) at Colchester in 1980.]]
All but four locomotives had been broken up for scrap by the end of 1972.<ref name = "bradley tws"/> The four Class 15s that survived were used for departmental service for a time, for which they were converted into non-powered electric train pre-heating units based at [[Doncaster Works]]. These duties kept the locomotives in active use for another ten years or more, until these final examples were again found to be redundant and finally withdrawn.{{Citation needed|date=December 2020}}

{| class="wikitable"
!Original Number!!Departmental number!!Location!!Withdrawn!!Disposal<ref>{{cite web | last = Furness | first = Ian| title = Disposals: Class 15 | publisher = wnxx.com | url = http://www.wnxx.com/disposals/class15.htm | access-date = 18 May 2011}}</ref>
|-
|D8203||ADB968003||Finsbury Park (FP)||1981|| Scrapped, 1981
|-
|D8233||ADB968001||Finsbury Park (FP)||1982|| Preserved
|-
|D8237||ADB968002||Finsbury Park (FP)||1982|| Scrapped, 1985
|-
|D8243||ADB968000||Finsbury Park (FP)||1989|| Scrapped, 1991
|-
|}

== Preservation ==

[[File:D8233Wiki.jpg|thumb|right|Sole surviving Class 15 no D8233 seen at Baron Street Loco Shed, [[East Lancashire Railway]], February 2006]]
One of the former train heating units, D8233, was purchased for preservation in 1984 and is now the only survivor of the type. It was originally kept at the [[Heritage Shunters Trust|South Yorkshire Railway]] in Sheffield, moving in 1986 to the [[East Lancashire Railway]], and in 1988 to the [[Mangapps Farm Railway Museum|Mangapps Farm Railway]], where it remained until 1993. D8233 then moved to [[Crewe Heritage Centre|Crewe]] following an agreement with the Waterman Heritage Trust. Since its initial preservation the locomotive had received little work apart from cosmetic attention. Some work was carried out by the Waterman Heritage Trust, however the locomotive's restoration remained dormant until the end of 2005, when a reformed owning group, alongside the WHT, agreed the time was right to accelerate the locomotive's return to service. With an active plan for work agreed, the locomotive returned to the East Lancashire Railway in February 2006, where its restoration to working order is now under way.<ref>{{Cite web|url=http://www.d8233.org.uk/|title=Class 15 Preservation Society &#124; News|website=d8233.org.uk}}</ref><ref name = "bradley tws"/>

==Models==
A ready to run model in [[00 gauge]] was available from TechCad design based on a hand finished resin shell and powered by a Mashima motor. It was then available from TechCad as a kit, but TechCad have since ceased trading. Since 2010, [[Heljan]] have produced an OO gauge ready-to-run model in a variety of liveries.<ref>{{Cite web|url=https://www.hattons.co.uk/26332/heljan_1503_class_15_d8233_in_br_green_with_small_yellow_panels_as_preserved_limited_editi/stockdetail|title=Heljan 1503 Class 15 D8233 in BR green with small yellow panels – as|website=hattons.co.uk}}</ref> The Heljan model was first announced in 2008 and introduced as D8233 in BR green.<ref>{{cite magazine|title=Heljan's BTH Type 1 wins respect|first=Mike|last=Wild|magazine=Hornby Magazine|pages=72–73|issue=35|date=May 2010|location=Hersham|publisher=Ian Allan Publishing|issn=1753-2469|oclc=226087101}}</ref>

An [[N gauge]] kit of a member of the class is available from BH Enterprises, powered by a [[Graham Farish]] [[British Rail Class 20|Class 20]] chassis.<ref>{{Cite web |url=http://www.bh-enterprises.co.uk/page8.htm |title=BH Enterprises Locomotive Kits |access-date=14 April 2010 |archive-url=https://web.archive.org/web/20100613044353/http://www.bh-enterprises.co.uk/page8.htm |archive-date=13 June 2010 |url-status=dead }}</ref>

An [[O gauge]] ready-to-run model was produced by Little Loco Company<ref>{{cite web |url=http://www.littleloco.co.uk/product/bth-type-1-class-15/ |title=BTH Type 1 / Class 15 |website=Little Loco Company |archive-url=https://web.archive.org/web/20190221081425/http://www.littleloco.co.uk/product/bth-type-1-class-15/|archive-date=21 February 2019 |url-status=dead}}</ref>

==References==
===Citations===
 {{Reflist}}

===Sources===
*{{Cite book |title=Diesel Pioneers |last=Clough  |first=David N. |publisher=[[Ian Allan Publishing|Ian Allan]] |year=2005 |isbn=978-0-7110-3067-1 |chapter=Pilot Scheme Prototypes of Type A/Type 1: BTH D8200 series (later Class 15) |pages=41–45}}
* {{cite book | last = Stevens-Stratten | first = S.W. |author2=Carter, R.S. | title = British Rail Main-Line Diesels | publisher = Ian Allan Ltd | year = 1978 | location = Shepperton | isbn = 0-7110-0617-2}}
* {{cite book | last = Williams | first = Alan |author2=Percival, David | title = British Railways Locomotives and Multiple Units including Preserved Locomotives 1977 | publisher = Ian Allan Ltd | year = 1977 | location = Shepperton | isbn = 0-7110-0751-9}}
* {{cite book | title = British Railways Locoshed Book 1977| year = 1977 | publisher = Ian Allan Ltd | location = Shepperton | isbn = 0-7110-0752-7}}
* {{cite book | last = Sugden | first = S.A. | title = Diesel & Electric Loco Register (3rd edn) | date = April 1994 | publisher = Platform 5 | location = Sheffield | isbn = 1-872524-55-9}}
* {{cite book | last = Grindlay | first = Jim | title = British Railways Locomotive Allocations 1948-1968 (Part 6 – Diesel & Electric Locomotives) | year = 2006 | publisher = Modelmaster Publications | location = Troon | isbn = 978-0-9544264-6-0}}

==Further reading==
*{{cite book|title=British Rail Main Line Diesel Locomotives|first1=Colin J.|last1=Marsden|first2=Graham B.|last2=Fenn|pages=56–59|publisher=Haynes|location=Sparkford|year=1988|isbn=9780860933182|oclc=17916362}}
* {{cite book |last=McManus |first=Michael |title=Ultimate Allocations, British Railways Locomotives 1948–1968 |publisher=Wirral. Michael McManus }}

== External links ==
{{commons category|British Rail Class 15}}
* [http://www.d8233.org.uk Class 15 Preservation Society, Owners of sole surviving Class 15, D8233]
* [http://wmbusphotos.com/Trains/class15/D8233.html Photograph of ADB968001, former D8233 at Stratford 12 September 1981]
* [https://www.hattons.co.uk/26332/heljan_1503_class_15_d8233_in_br_green_with_small_yellow_panels_as_preserved_limited_editi/stockdetail.aspx Heljan 1503 Class 15 D8233 in BR green with small yellow panels – as]
{{British Rail Locomotives}}

[[Category:British Rail diesel locomotives|15]]
[[Category:Bo-Bo locomotives]]
[[Category:BTH locomotives]]
[[Category:Clayton locomotives]]
[[Category:YEC locomotives]]
[[Category:Railway locomotives introduced in 1957]]
[[Category:Standard-gauge locomotives of Great Britain]]
[[Category:Diesel–electric locomotives of Great Britain]]
[[Category:Freight locomotives]]