Design Each vehicle carries its own powertrain, driving both axles on one of the vehicle's bogies via cardan shafts. Each powertrain consists of a Cummins QSK19 turbo-diesel engine driving a Voith T312bre three-speed hydrokinetic transmission, which in turn drives the axles via Voith SK-485 and KE-485 final drives. 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. The transmission includes an integrated hydraulic retarder. Cooling fans and the electrical generator are powered via a hydrostatic drive. The electrical generator provides a 400 V 50 Hz three phase electrical supply for the train, which is transformed or rectified to a 230 V 50 Hz single phase supply, a 110 V DC auxiliary supply, and a 24 V DC battery supply. Connections bridge the main 400 V AC and 110 V DC supplies across the cars of each train set. Component suppliers included Dellner (couplings), ZF (dampers), SKF (bearings), and Westinghouse Brakes (now Knorr-Bremse, braking systems). The bogies are derivatives of Siemens' SF5000 type, and were manufactured in Graz, Austria. The design has an distance between each axle of , with radial-arm primary suspension utilising steel coil springs with rubber elements; the secondary suspension is an air spring design supporting a bolster. Motor bogies have traction forces transmitted from bogie to frame via rods from a centre pivot. Mechanical brakes are wheel mounted discs. The Class 185 is heavier and has a stiffer suspension than the Class 158 it replaced on some routes; On some routesincluding the Hope Valley Line, York to Scarborough Line, Hull to Selby Line, and between and the Class 185 units were not permitted to operate at the same speeds as Sprinter-type DMUs; however the higher acceleration of the Class 185 units could be used to partially offset the lower speed restriction. Between Northallerton and Middlesbrough, Class 185s and Sprinters now use the same speed limits. As delivered each train consisted of three cars; one end car (DMOSB) had 64 standard class seats in [2+2] arrangement with a mixture of facing seats with tables and airline style arrangements, as well as luggage and bicycle facilities; the middle car (MOSL) had 72 standard class seats also in a mixture of arrangements in [2+2] formation, and incorporated a standard toilet; the other end