British Rail Class 121
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|British Rail Class 121|
|Manufacturer||Pressed Steel Company|
|Number built||16 motor cars
10 trailer cars
|Number preserved||5 motor, 2 trailer|
|Line(s) served||Princes Risborough to Aylesbury Line|
|Car body construction||Steel|
|Car length||64 ft 6 in (19,660 mm)|
|Width||9 ft 3 in (2,820 mm)|
|Height||12 ft 4 in (3,760 mm)|
|Weight||DMBS: 37 tons 8 cwt (83,800 lb or 38.0 t),
DTS: 29 tons 7 cwt (65,700 lb or 29.8 t)
|Multiple working||■ Blue Square|
|Track gauge||4 ft 8 1⁄2 in (1,435 mm)|
Sixteen Class 121 single-car driving motor vehicles were built from 1960, numbered 55020–55035. These were supplemented by ten trailer vehicles, numbered 56280–56289 (later renumbered 54280–54289). They had a top speed of 70 mph, with slam-doors, and vacuum brakes. The driving motor vehicles were nicknamed "Bubble cars" by some enthusiasts (a nickname now endorsed by current operator Chiltern Railways).
The Class 121 is Britain's longest serving DMU, having been in service for 54 years as of 2014.
British Railways service
The Class 121 were built for use on the Western Region of British Rail. They were used on various lightly used branch lines, including the Looe branch line (and various other branch lines) in Cornwall, the branch lines off the main line in the Thames Valley, the Severn Beach line in Bristol and the Greenford Branch Line in West London.
Class 121s were built with distinctive exhaust pipes, designed to fit around a large four-digit route headcode indicator box at roof level. Use of the headcode indicator box was discontinued in the 1970s, so the indicator was removed and the hole plated-up when the units were refurbished.
They also had a small destination indicator inside the top of the centre cab window.
The similar Class 122 units had the small destination indicator in the cab roof in place of the large headcode box. They were used on the other regions of British Rail.
Upon privatisation of Britain's railways, the Class 121 fleet was only operated by one passenger company, namely Silverlink, with several more units in departmental duties with Railtrack. There are three examples left in revenue-making service.
In 2003, Chiltern Railways reintroduced "Heritage" diesel multiple units on its Aylesbury to Princes Risborough shuttle service. For this purpose, unit 121020 (vehicle 55020) was purchased from Network Rail, and heavily refurbished to allow it to operate passenger services. It was repainted into Chiltern Railways blue livery. The introduction of this unit allowed the release of a Class 165 "Turbo" unit for refurbishment. This unit has been fitted with secondary (magnetic) door locking and other safety features, and thus was exempt from the 30 November 2005 deadline for the withdrawal of all Mark 1 vehicles.
In May 2011 a second Bubble Car was reintroduced to regular service. Unit 121034, previously based at Tyseley Loco Works, was refurbished for use by the Birmingham Railway Museum. It is painted in a green livery and is used on Aylesbury to Princes Risborough services when required.
In March 2013, Chiltern Railways acquired 121032 from Arriva Trains Wales.
Network Rail operates a small fleet of former Class 121 vehicles for various departmental roles. These have been reclassified as Class 960 departmental units. Duties include route learning, video surveying of track and sandite application. Two members of the fleet were also stabled at Severn Tunnel Junction for emergency evacuation of the Severn Tunnel, where they were never used,[clarification needed] and eventually disposed of. Units are painted in various liveries including Network SouthEast (NSE), South West Trains blue/red, Railtrack's brown livery, Railtrack's blue/green livery, and Network Rail's new all-over yellow livery. In addition, two units have been specially repainted in old BR liveries, namely maroon and blue/grey. The units stabled at Aylesbury are jointly used by Chiltern Railways for route learning.
Modern day operations gallery
Chiltern Railways' refurbished Class 121 No. 121020 at Quainton station, site of the Buckinghamshire Railway Centre, 3 May 2010
Arriva Trains Wales refurbished Class 121 No. 121032 Cardiff Queen Street
The current fleet is listed below:
|Unit no.||Vehicle no.||Livery||Use||Status|
|Departmental no.||Former no.|
|960002||977722||55020||Network South East||Sandite/Route-learning unit||In Service|
|960021||977723||55021||Railtrack Brown||Sandite/Route-learning unit||Scrapped in 2011 (whilst at Aylesbury)|
|960014||977873||55022||BR Blue/Grey||Route-learning unit||In traffic (At Aylesbury)|
|960010||977858||55024||BR Maroon||Sandite unit||Under restoration (At Chinnor & Princes Risborough Railway since Oct 2013)|
|960011||977859||55025||Railtrack Blue/Green||(Ex Video survey unit, now Route Learner)||Stored|
|960013||977866||55030||NSE||Sandite unit||Scrapped in 2011 (whilst at Aylesbury)|
|-||977842||55032||Arivia trains Wales||-||In Service|
Silverlink inherited a small fleet of four "Bubble Cars". They were mainly used on the Marston Vale Line from Bletchley to Bedford, as well as non-electrified lines in North London, such as Gospel Oak to Barking. The units replaced the previous fleet of Class 108 and Class 115 units, and were supplemented with a fleet of Class 117 units cascaded from Thames Valley services.
The four units, nos. 55023/27/29/31, were based at Bletchley depot, where staff repainted set L123 (55023) into its original British Railways green livery. The others remained in obsolete Network SouthEast livery. In 1996, set L123 was withdrawn from traffic, and the other three were hired to Great Eastern for use on the Sudbury branch to Sudbury. These returned to Bletchley in 1997/98. Two of the units (121027/029) were repainted into Silverlink's purple and green livery, and the third (121031) was repainted into Network SouthEast livery. The three units also received names from withdrawn Class 117 units.
Arriva Trains Wales
In 2006, unit 121032 was purchased by Arriva Trains Wales for use on the Cardiff Bay Shuttle. The unit has been repainted into Arriva colours and was hauled to Wales in June 2006 to enter service in July. The unit finally entered service on 16 August 2006 but was withdrawn 3 days later due to a major problem with the engine. The unit re-entered service on the Cardiff Bay line on 14 September 2006. The unit has been regularly seen on the Barry Tourist Railway during training purposes for the unit. In March 2013, 121032 was withdrawn from service due to an engine problem which could not be rectified. It was subsequently sold to sister company Chiltern Railways for use as a spare parts donor.
"Bubble Cars" have proved popular for preservation on heritage railways. Including some in the class still in Service.
|Vehicle no.||Unit no.||Vehicle type||Location||Comments|
|Original no.||Departmental no.|
|56287||-||L211||DTC||Colne Valley Railway||-|
|56289||-||L263||DTS||East Lancashire Railway||-|
|55023||-||L123||DMBS||Chinnor & Princes Risborough Railway||Repainted into BR Green livery whilst based at Bletchley depot.|
|55026||977824||P126||DMBS||Swansea Vale Railway||After the fire attack on the Swansea Railway in 2008, the unrestored vehicle was left gutted. On merger of the society with the Gwili Railway, and considered damaged beyond economic repair, the locomotive was scrapped at Ammanford Metal Recycling in Spring 2009|
|55027||977975||P127||DMBS||Barry Tourist Railway||Previously Severn Tunnel Emergency train 960302, sold to Barry tourist Railway around January 2014|
|55028||977860||L128||DMBS||Swanage Railway||Recently sold by South West Trains, it was used as a departmental route-learning unit. Currently in B.R "Heritage" green with "D.M.U Whiskers" livery after a major overhaul was undertaken after its arrival.|
|55029||977968||L129||DMBS||Rushden, Higham and Wellingborough Railway||Recently sold by Colas Rail from store at Rugby. It was converted there into non-passenger carrying stock.|
|55031||977976||T002||DMBS||Barry Tourist Railway||Previously Severn Tunnel Emergency train 960 303, sold to Barry tourist Railway around January 2014|
|55033||977826||T004||DMBS||Colne Valley Railway||Painted in experimental MidLine livery. It's currently in B.R "Heritage" green with "D.M.U Whiskers" livery.|
|55034||977828||T005||DMBS||Tyseley Locomotive Works||-|
|Class||Operator||No. in Service||Year Built||Cars per Set||Unit nos.||Notes|
|Class 121||Chiltern Railways||3||1960||1||121020, 121032, 121034||121032 used as spares donor|
|Network Rail||8||121021/022, 121024/025,
|Reclassified as Class 960|
Remarkably, considering the age of the fleet, the oldest unit (55020) is still in daily service, whilst the youngest vehicle (55035) was the first to be dismantled. As of early April 2011, 55021 (960021) and 55030 (960013) have also been dismantled. This could change in the future, due to the former Severn Tunnel Emergency Train sets are being stripped for spares at Cardiff to keep 55032 running.
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