SNCB Class 27


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Class 27  
Technical details




SNCB 2708 at Brussels Midi March 2003 - Picture by Mike Pringle


SNCB 2743 at Blankenberge 26th June 2003 - Photo by Mike Pringle


Extract from Timeline Article

New Motive Power in Belgium

Belgian National Railways (SNCB) has just premiered the first elements of a new generation of electric locomotives and multiple units, the mixed traffic Class 27 locomotive and Class AM80 EMU. Both have chopper control and both are arranged for 160km/h maximum speed which will match the SNCB civil engineering to enhance the speeds on the Ostend-Brussels-Liege, Roosendaal-Brussels-Quevy, Gent-Kortrijk and Mons-Mouscron lines from the generally prevailing 140km/h in Belgium.
Expansion of SNCB’s electric traction resources is also needed to keep pace with a rolling electrification programme which was set to have a total of 2,450 route km equating to 60% of the system under the wires by 1987. That deadline has slipped by at least 2 years following Government budget cuts made to tackle the countries serious economic difficulties. The SNCB capital programme was not spared in these cutbacks and its 1982 Government Credits cut by Bfr5billion. The result of this is likely to see a slow down in EMU deliveries as well as the somewhat slower pace of electrification.
The 4,150kW (5650hp) Class 27 Bo-Bo’s are being assigned to express-train haulage on the Ostend-Brussels-Liege-Aachen axis but are equally at home on heavy freight and they have been designed to haul such trains on the Antwerp-Montzen-Aachen line. Hitherto these trains have been hauled by 1,800kW (2560hp) units of Class 22 and 23 which despite being under-powered for these duties, are also constrained by a 130km/h maximum speed which is short of the ruling line speed.
The Class 27 specification sets out a requirement for the locomotive to maintain a speed of 160km/h with a load of 600 tonnes which is the equivalent of about 13 international coaches. For freight the requirement is to haul 800 tonnes at a sustained speed of 80km/h on the Luxembourg trunk route where there is an average gradient of 1 in 83 for approximately 20km, with some stretches worsening to 1 in 62.5. Elsewhere the Class 27 will be expected to cope with 2000 tonne freights without batting an eyelid.
The Class 27 is fitted for MU operation and this specification will apply to all future SNCB locomotive orders since this type of working is to be expanded considerably. Another new feature for the SNCB and one which also applies to the new AM80 EMU is automatic couplers. These should provide considerable timesaving and improve staff safety. The downside here of course is that at present the AM80 cannot work in multiple with any other stock.
The Class 27’s are SNCB designed and Belgian built with mechanical parts from BN and electrical equipment from ACEC. External finish is a peacock blue with horizontal yellow bands over body ends and sides and set off by a lighter blue finish to the roof.
Chopper technology was first used on SNCB in 1969 and this has been used in traction packages since 1972, mostly in EMU’s but also including the Class 20 5,820kW Co-Co’s of 1975. Besides the improvement in traction characteristics, SNCB expects to see lower maintenance costs and reduced catenary wear. With a compact network and fairly short spaced stops, thyristor control, reduces the demands on the system from frequent stops and starts.
The Class 27’s power equipment has been designed for simplicity and ease of maintenance and with the objective of avoiding total failure of a locomotive out on the road. Pairs of traction motors connected in series and fed by a chopper forma n independent power circuit with the traction auxiliaries supplied by a static inverter. In the event of one power circuit becoming a complete failure, the Class 27 can still make full speed but on half power, provided the load dos not make this unduly difficult. As an alternative, full tractive effort can be secured by connecting all four motors to one of the choppers but at the cost of halving the speed. It is also possible to switch the auxiliary feed to a second inverter though with the loss of some traction performance. A drivers diagnostic display in the cab displays faults allowing the driver to decide which systems to bypass by showing which switches on the equipment room panel should be moved to get the locomotive on the move again. Class 27 is the first SNCB machine to be fitted with rheostatic brakes which can be applied independently or blended with the air brakes.
Total order is for 60 units originally scheduled for delivery by October 1983. These will be followed down the production line by a les powerful design, Class 21 which shares many of the components and systems with its more powerful brother. At 3,150kw, 30 units are expected to be delivered by the Autumn of 1984. The other locomotives in the series will be multi-voltage versions of Class 21. There will be 12 1,000/3,000v dc Class 11’s designed for working the Brussels-Amsterdam inter-city in push-pull mode, and 12 3,000v dc/25kv 50Hz Class 12 for through working on to the SNCF system with through trains from Brussels to Lille via Baisieux. These workings however are dependent upon completion of the electrification works between Tournai and Lille. The Class 11 and Class 12 are not scheduled for delivery until late 1984.

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