INTRO: Netherlands Railways unveiled its first Bo’Bo’Bo’ power car at Leidschendam on November 12; the 2·4MW vehicles will work with double-deck coaches in four or five car sets. Harry Hondius reports

BETWEEN 1992 and 1994, Netherlands Railways put into service 258 double-deck coaches for commuter operations in the Randstad region. Built by Talbot with SIG bogies, the DDM stock was formed into push-pull sets with 81 4·4MW B’B’ locos of Class 1700 from GEC Alsthom. The 79 driving trailers, 103 second class coaches and 76 composites formed 49 three-car and 27 four-car sets.

Although equipped with BSI automatic couplers, the Class 1700s were really only a quick-fix engineering solution to get the DDMs running. They are a derivative of the 58 Class 1600s of 1981-85, which in turn were based on SNCF’s BB7200 design. From the outset, NS intended to develop a double-deck power car for the DDMs, which would cascade the 1700s to replace locos dating from the 1950s.

NS Engineering began studies for the motor coach in 1990, leading to a call for tenders in autumn 1992. An order for 50, with an option for another 29, was awarded in January 1993 (RG 3.93 p227). After a further year of detailed engineering design, construction began in January 1995. According to project manager Joop Hertel, NS Engineering has paid the industry 50m guilders in development costs. An old EMU car was shortened to the length of the mDDM and fitted with three new bogies for extensive riding trials.

Lead contractor De Dietrich is responsible for mechanical parts, with the bogies coming from Fiat-SIG Schienenfahrzeuge of Switzerland. Electrical equipment is the responsibility of Adtranz Netherlands, with the electronics coming from Mannheim and the traction motors from Wien. Two-thirds of the bogies were subcontracted by FSS to Stork-RMO of Amsterdam, whilst half of the traction motors are coming from Holec Ridderkerk. Electrical installation at Reichshoffen is being managed by Holec Projects. Final price is 5·5m guilders per car. The aim is to have three power cars available for tests during 1997, with series deliveries from October 1997 to the end of 1998.

Innovative design

NS Engineering has developed an interesting and practical vehicle, with the traction equipment on the lower deck and a passenger saloon above. To maintain a low entrance height with 2·4 MW installed power, NS opted for a three-bogie layout and six 400 kW traction motors. This also gives a very low axleload. A demonstration run on the Rotterdam Hofplein line showed good riding qualities at up to 100 km/h, and NS engineers say tests between Horst and Eindhoven have shown excellent riding up to 155 km/h, well above the 140 km/h design speed. The ambient noise level is also very good, with the electronics quite silent in full operation.

Using mDDMs will give an extra 16 first and 32 second-class seats for a 3m increase in train length. The 50 power cars provide the equivalent capacity of 18 more double-deck trailers.

The welded all-steel car has three modular bogies, with a rubber/air secondary suspension. The bogies are identical, apart from different bump stop locations giving extra lateral movement for the centre bogie. On each bogie there is a central pivot, and the bolster is linked to the bogie frame via two longitudinal traction rods. Two horizontal dampers and two longitudinal yaw dampers are mounted between bolster and bogie frame, and an anti-roll stabiliser. Coil springs and vertical shock absorbers make up the primary suspension.

The ABB force-ventilated AC motors are fully-suspended, and drive through a BSI gear and Paket couplings. Four fans are used to cool the six motors.

The nominal 1·5 kV DC traction supply, which actually ranges from 1·2 to 1·8 kV, is collected by two Faiveley pantographs. It is fed to the motors via a DC filter and two oil-cooled GTO PWM inverters able to work in the range 1·0 to 2·1 kV. Traction control uses Micas-S microprocessors and a vehicle databus linking all the sub-systems.

Dynamic braking is regenerative up to a live voltage of 1·7 kV, after which GTO-chopper controlled rheostatic brakes are blended in to take over completely above 1·8 kV. The resistances are roof-mounted. Knorr-Oerlikon air brakes with direct actuation are fitted to the outer bogies, whilst the centre bogies use spring actuation which also provides a parking function.

Auxiliaries are powered by two 78 kVA IGBT inverters which are fed by a chopper at 600V DC and supply 440V at up to 60Hz for motors, oil coolers and DC filter fans, or 380V 50Hz for the compressor and oil pump. There is a 110V DC supply to the 46Ah battery and 72V DC for the controls. The Hagenuk -Faiveley warm air heating and ventilation equipment is roof-mounted. Two Tebel electro-pneumatic plug doors with a net width of 900mm are fitted on each side. o

CAPTION: The mDDM power car is carried on three identical Fiat-SIG bogies, with a 400 kW AC motor driving each axle. There are 16 first and 32 second class seats on the upper deck

Technical data for NS

mDDM power cars

Length over car body mm 20830

Body width mm 2780

Overall height mm 4600

Doorway height above rail mm 1183

Saloon floor height above rail mm 2030

Interior height of saloon mm 2050

Bogie wheelbase mm 2750

Bogie centres mm 2 x 7250

Wheel diameter (new) mm 920

Maximum power rating kW 6 x 390

Continuous rating kW 6 x 328

Weight empty tonnes 76

Maximum acceleration (4 car train: 1+3) m/s2 0·6

Maximum braking rate m/s2 1·3

Maximum service speed km/h 140

Minimum curve radius m 135