Looking to replace its varied fleet of 1435mm gauge main line diesel traction, largely built before 1975 and now suffering from poor availability, performance and fuel consumption, Hellenic Railways Organisation (OSE) ordered 26 Bo-Bo diesel-electric locomotives from ABB Henschel (now Adtranz) in 1995. Costing a total of DM210m, the Class A471 units will be deployed on passenger and freight services between Athens and Thessaloniki.

OSE has completed electrification at 25 kV 50Hz AC of the 78 km between Thessaloniki and the Macedonian border at Idomeni, and required its new diesels to be capable of conversion to straight electric operation once the electrification of its main line to Athens is complete. Retaining their mechanical parts, power converters and most electronic equipment, the 2100 kW diesels would then become the projected Class E5000, rated at 5500 kW and with a maximum speed of 200 km/h.

Twin engines

The Adtranz works in Kassel, Germany, was project leader for the OSE diesels, designated DE2000 by the manufacturer. Final assembly was undertaken at Oerlikon in Switzerland. Derived from previous modular designs such as the Class 460 for Swiss Federal Railways and the Class 101 for German Railway (RG 8.96 p506), the OSE locos have lightweight steel bodies from Adtranz Pafawag of Poland, with aluminium roof panels supplied from Derby in Great Britain.

Each loco is powered by two MTU engines, each with a nominal rating of 1050 kW; these are similar to the power packs supplied for OSE’s diesel-electric multiple-units built by AEG. The loco can operate on one or both engines as required. Traction motors and alternators were supplied by Adtranz Austria, with other electrical equipment produced by the company’s Mannheim works in Germany.

The A471 has a three-phase drive, with an intermediate DC link providing auxiliary power and the train heating supply. The drive incorporates modular oil-cooled inverters with GTO thyristors, and the locomotives are equipped with dynamic braking. The Micas S control system incorporates a diagnostic function, with warnings of malfunctions presented by a colour display in the cab, together with suggested countermeasures.

To meet OSE’s nominal axleload limit of 20 tonnes - within a basic performance requirement of hauling 800 tonnes at 30 km/h on a 2·1% gradient - the locos ride on Flexifloat bogies manufactured at Kassel and Siegen. Suspended between the body and the bogie frame, each traction motor drives through a gearbox and flexible coupling, reducing track forces in line with OSE’s requirement for lower maintenance costs on the sharp curves and steep gradients of its Athens - Thessaloniki route. o

Outline technical data

Number ordered 26

Gauge mm 1435

Wheel arrangement Bo-Bo

Weight in running order tonnes 81·6

Continuous rating at crankshaft kW 2100

Continuous tractive effort kN 230 at 25 km/h

Starting tractive effort kN 260

Engine 2 x MTU 12V396TC13

Maximum speed km/h 160

Length over buffers mm 19400

Distance between bogie centres mm 11200

Bogie wheelbase mm 2650

Wheel diameter when new mm 1100