Class 314 units were formed of two vehicles with driver's cabs sandwiching a trailer vehicles that carried the pantograph and high-voltage transformer.^[1] The 25 kV supply collected from the overhead lines by the pantograph was passed from the transformer in the intermediate trailer to four 110 horsepower (82 kW) direct current traction motors mounted under each driving car.^[3][4][5]

In common with the other classes of BREL's 1972 family, Class 314 vehicles were of constructed of aluminium alloy on a steel underframe and had pneumatically-actuated sliding doors.^[1] Tightlock couplings allowed units to be coupled and uncoupled by the driver alone from within the cab, a simplification compared to the coupling procedure used by the Strathclyde network's then-existing Class 303 units.

The sixteen-strong Class 314 fleet had been acquired for the main purpose of operating the newly-opened Argyle Line, which they did—along with the North Clyde Line—from introduction in late 1979^[6] until October 1999. After this they were transferred to operate Cathcart Circle services on the southern side of the Strathclyde network, covering for the withdrawal and scrapping of the Class 303 fleet.^[7] A small number of Class 314 units also worked Inverclyde Line services to Gourock and Wemyss Bay, mostly during peak hours.

From November 2012 the fleet additionally operated services on the Paisley Canal Line, following its electrification.^{[citation needed]}

A minor overhaul programme between May 2006 and mid-2007 included electrical upgrades and installation of improved door actuation mechanisms.

Between 2009 and 2010, the fleet received a life-extension (C5E) overhaul that included refurbishment and/or replacement of the bogies, and alterations to the driver's cabs.^{[citation needed]}

Between 2011 and 2013, five units received a C3 major overhaul at Railcare Springburn, which included corrosion repairs, repainting of internal surfaces, replacement of linoleum flooring material, replacement of seat covers, refurbishment of bogies and couplers, reliability upgrades and repainting into the then-new ScotRail Saltire livery. Eight other units underwent the C3 overhaul but were not repainted, while the remaining three units received the same internal refurbishment but a less-intensive C4 overhaul.^[8]

A further two units were repainted into the new livery in 2016, leaving nine in SPT's carmine and cream colours until their withdrawal.^{[citation needed]}

The increasing age of the Class 314 units, along with their failing to comply with the PRM-TSI requirements, made it unlikely that they would remain in service into the 2020s without further costly refurbishment.^[5] Ultimately this became unnecessary, as the continuing introduction of new Class 385 units created sufficient spare capacity in the PRM-compliant Class 318, 320, and 380 fleets to support withdrawal of the Class 314 fleet.^[9]

ScotRail announced in May 2019 that Class 314 units would begin to be replaced by Class 385s on the Inverclyde Line that same month, leaving only three services—all early on weekday mornings—to be operated by 314s.^[10] Further withdrawals occurred throughout 2019, and the final Class 314 passenger service was worked from Paisley Canal to Glasgow Central by 314216 on 14 December 2019.^[11]

ScotRail held a farewell tour for the class on 18 December 2019, with units 314202 and 314205 operating a special service around the ScotRail network, running to Ayr, Carstairs, Cumbernauld, and Helensburgh. The tour raised funds for ScotRail's charity partner MND Scotland.^[12] In the following year, all but one of the withdrawn units was scrapped.^[5]

In February 2020, ScotRail announced plans to convert the remaining unit, 314209, to be powered by on-board hydrogen fuel cells. The initiative is intended to study the feasibility of using hydrogen to fuel trains, as part of ScotRail's commitment to end its use of diesel fuel for traction by 2035.^[13][5] The project was initially handled primarily by a workgroup at the University of St Andrews, before a request for tenders was issued in September 2020 seeking a commercial partner for the full design, installation, and demonstration of a hydrogen fuel system using the Class 314 unit.^[14][15] In December 2020 the unit was moved to the Bo'ness and Kinneil Railway, near Falkirk, for conversion work to begin.^[5]

The lead contractor for the conversion work was rolling stock refurbishment firm Brodie Engineering, with Arcola Energy acting as hydrogen energy specialists.^[5] Arcola's A-Drive fuel cell powertrain forms the core of the new traction system, with hydrogen tanks and battery modules installed underneath all three vehicles. The increased weight of the new components was carefully measured and controlled in order to avoid exceeding the unit's maximum permissible axle load and to reduce the likelihood of the unit's kinematic envelope increasing; it was partially offset by replacing the original traction motors with new alternating current models.^[5] The intent is for the demonstrator to remain reasonably similar to a "standard" Class 314 unit, so that it can be run under its existing certificates of conformity for the general railway network.^[5]

In September 2020, it was announced that the demonstrator would appear at the COP26 Climate Change Summit, to be held in Glasgow during November 2021.^[16] The unit was to operate special services for the benefit of visiting delegates.^{[needs update]} In advance of the summit the unit was reclassified into the alternative-fuels class number range and renumbered 614209.^[17]

An acknowledged limitation of the Class 614 demonstrator is that it can only carry 80 kg (180 lb) of hydrogen, pressurised at 350 bar (35,000 kPa). This is sufficient for short-distance operation as a prototype, but storage capacity will need to be significantly increased for normal passenger service to be feasible.^[5] The project team claim that it will be possible to achieve this increase by installing additional storage tanks within the vehicles – a necessity as the UK's standard loading gauge does not allow enough space for roof-mounted tanks.^[5]

• On 21 July 1991, unit 314203 was damaged in the Newton rail accident. The leading DMSO vehicle was destroyed, but later replaced with the BDMSO vehicle from written-off Class 507 unit 507022.^[b] The repaired unit re-entered service in May 1996.^[7][20]
• On 12 December 1994, units 314208 and 314212 were severely damaged when they were caught in floodwaters in the low-level platforms at Glasgow Central. Extremely heavy rain had caused the River Kelvin to overflow its banks near the former Kelvinbridge railway station, from which the floodwaters flowed into the disused Kelvingrove and St Vincent Crescent tunnels of the Glasgow Central Railway and thence into the active Argyle Line tunnels near Exhibition Centre.^[21][22] Both units were later returned to service, but the Argyle Line through Glasgow Central remained closed for ten months whilst under repair.^[23]

Vehicle numbering edit

Individual vehicles were numbered in the ranges as follows:^[25]

• DMSO: 64583–64614
• PTSO: 71450–71465

DMSO numbers are sequential within units; thus vehicles 64583 and 64584 were in unit 314201, 64585 and 64586 in 314202, and so on.

Named units edit

• 314203: European Union (1996–2011)

Illustrations edit

• Marsden, Colin J. (1982). EMUs. Motive Power Recognition. Vol. 2. Ian Allan. pp. 50–51. ISBN 9780711011656. OCLC 16537600.