| lines =
| carbody = Aluminium
| height =
| lowfloor =
| floorheight =
| platformheight =
| entrylevelorstep =
| wheeldiameter =
| wheelbase = Bogies:
| maxspeed =
| weight = Approx.
| axleload = max.
| steep gradient =
| traction =
| engine = 3 × Cummins QSK19-R
| displacement = per engine
| tractiveeffort =
| transmission = Voith T312bre<br />(hydrokinetic, one per car)
| acceleration =
| deceleration =
| aux =
| powersupply =
| hvac =
| uicclass = 2′B′+B′2′+B′2′
| bogies = Siemens SGP SF5000
| minimum curve =
| multipleworking = Within class
| gauge =
| notes = Sourced from except where otherwise noted
The British Rail Class 185 Desiro is a class of diesel-hydraulic multiple-unit (DHMU) passenger trains built by Siemens Transportation Systems in Germany for the train operating company First TransPennine Express. They are currently operated by TransPennine Express.
A £260 million order for 51 three-car trains and associated maintenance depots was placed in 2003, and deliveries took place between 2006 and 2007.
Background and history
thumb|left|Class 185 at York in [[First TransPennine Express Dynamic Lines livery]]
In 2003, First TransPennine Express (FTPE), a consortium of FirstGroup and Keolis, was awarded the TransPennine Express (TPE) franchise. One obligation under the franchise agreement was to introduce a new fleet of diesel multiple units, capable of operating at speeds up to . Also specified was air conditioning, two toilets per vehicle with one suitable for reduced-mobility passengers, gangways between individual carriages, luggage and bicycle storage space, passenger compartment CCTV, provision for wheelchair passengers, and first-class seating. Additionally, the train's acceleration was to be an improvement on the , and comparable to the . The agreement specified 168 carriages, with an initial option to reduce the carriage order by 18.
The franchise agreement also required the construction of two depots for the new rolling stock; the main depot was to be at Manchester, with a depot for stabling and maintenance at York. In addition, a depot at Cleethorpes was to be upgraded with refuelling and controlled emission toilet servicing facilities, and a train electric auxiliary supply. The franchise agreement specified a performance aim of per casualty, with entry into service between March 2006 (first unit) and November 2006 (entire fleet).
By August 2003, Siemens had been named as the preferred bidder for the trains. A contract for supply and maintenance of 56 trains was signed in September 2003. The new train requirement was reduced from 56 to 51 units by the Strategic Rail Authority (SRA) by 2004.
The trains were built at Siemens' plant in Uerdingen in Krefeld; the first unit began test trials at the Wildenrath test circuit in July 2005.
Construction of the Ardwick train depot began March 2005 and was completed in 2006. Work started on the new Leeman Road depot in York in December 2005; opening followed in May 2007. In 2006, FTPE acquired two static simulators for driver training from Corys TESS.
All 51 trains were in service by January 2007. The trains replaced two and three-car and 175 units.
Design
thumb|left|Class 185 multiple working at York
Each vehicle carries its own powertrain, driving both axles on one of the vehicle's bogies via cardan shafts. The other bogie on each vehicle is unpowered. The engine and torque converter were frame-mounted underfloor and suspended from the car body by flexible mounts. A third underfloor module contains cooling systems and an electrical generator.