NDJ3

NDJ3
A NDJ3 approaching Qinglongqiao railway station
the buffet car, fitted with panoramic windows
Built at	CRRC Nanjing Puzhen CRRC Qishuyan
Entered service	2008
Number built	9
Number in service	9
Formation	M-T-T-T-T-T-T-T-M (China Railway) M-T-T-T-T-T-T-T-T-M (Nigerian Railway)
Operator(s)	China Railway Nigerian Railway Corporation
Specifications
Train length	220.5 m (723 ft)
Width	3,105 m (10,187 ft)
Height	4,433 mm (14.544 ft)
Wheel diameter	1,050 mm (3.44 ft) (power car, new) 970 mm (3.18 ft) (trailer, new)
Maximum speed	160 kilometres per hour (99 mph)
Axle load	21 tons
Traction system	eight 530 kW
Prime mover(s)	two 12V280ZJ
Engine type	diesel
Traction motors	ZD106
Power output	3530 kW
Tractive effort	4240 kW
Transmission	AC–DC
Acceleration	(1.368km/h/s) 0.38 m/s² (starting)
AAR wheel arrangement	A1A-A1A
Track gauge	1,435 mm (4 ft 8+1⁄2 in)

The NDJ₃ "Great Wall", previously labeled the "Harmony Great Wall" is the only standard speed diesel multiple unit that is still operating in China. It was first designed to be used for passenger transport in the 2008 Olympics, and has become a mature technology platform with export orders to Nigeria despite initial flaws related to overheating of electrical cables in the power car.

Description[]

To fulfil the need for passenger transport between Beijing and Badaling during the 2008 Summer Olympics,^[1] the Ministry of Railways ordered four NDJ₃ DMU trains,^[2] with the numbering NDJ₃ 0001-0004. All of them are with Beijing Bureau, Beijing sector Nanko depot, operating on Line S2 between Beijing North station and Badaling station via Yanqing station, with a later addition of another service from Beijing North to Shacheng station. These sets was the first diesel multiple units designed in China with the ability to negotiate ≥33‰ gradient and a curve of 180 metres, optimised for the steeper gradient of the S2 line, although this gearing for steeper lines also reduced the maximum speed from 180 km/h to 160 km/h, although they could be easily geared for higher speeds.^[2]

The NDJ₃ is developed from the with a similar 2M7T layout where motor cars are diesel locomotives located on either end in a push–pull configuration, while also drawing from the experience of DF11 and DF11G locomotives.^[2] The Qishuyan designed locomotives are fitted with a diesel-electric drive, generating AC which is then converted to DC for the traction motors. The main generator is supplemented by an auxiliary generator, which provides power to the passenger cabins. The Nanjing Puzhen designed passenger carriages are based on the while the exterior paint draws inspiration from the Harmony trains.^[3] The passenger carriages have wide doors, extra large sightseeing windows, rotatable seating, disabled toilets and other passenger amenities designed for increased passenger comfort.

Flaws[]

While running the S2 which has steep gradients, a burning smell was often noticed coming from the resistors that dissipate energy from braking. This was found to be the fault of cable 13, which heated up significantly in use. It was due to the design where the cable carries the power for both the Eddy current brake and the magnetic excitation for the 4th traction motor. The high temperatures poses a serious risk to safety, as it would degrad the cable faster, leading to a higher risk of fire, but also the risk of the brakes failing if the current is not supplied. At a speed of 28 km/h with the control lever on level 8 braking, the current exceeds the design limit by 1.72 times, and at around 33 km/h with 634 amps for the motor and 623 amps for the brake, the cable heats up to 55.4°C. To rectify this flaw, the cables for traction motor 4 were separated into separate cables for braking and motor power.^[4] Nonetheless, it has not had any serious accidents, and the set was awarded first place in the 2009 Railway Technology prize.^[5]

Service history[]

China[]

This train was put into operation on 6 August 2008 on Line S2. Although it carried the name "Harmony Great Wall" (Chinese: 和谐长城号),^[6][2] it does not actually belong to the Harmony series of trains. During their service, they have also occasionally been used on other lines.^[3]

At the end of 2017, Beijing bought two more sets for Huairou–Miyun line.^[7][8] These sets, numbered NDJ₃ 0005-0007 have only second class seating and do not have a buffet car, significantly increasing the seating capacity. Line S2 was also supposed to receive another three sets, but they were never delivered for unknown reasons.^[3]

From October 2019 onwards, the "Harmony" (Hexie) logos were gradually removed from the sets. These sets then carried only the "Great Wall" (Changchen) logos at the front.

Nigeria[]

In 2019, the Nigerian Railway Corporation ordered two sets, as part of the construction of standard gauge railways in the country, in an order with six DF11G, nine DF8 and two DF7 locomotives. In Nigerian service, the sets are classed as CDD5E1. These sets differ with a lower speed at 150 km/h, USB charging and have an additional trailer with wheelchair parking, compared to the second series of NDJ₃ delivered to Beijing. These sets commenced service with the Lagos-Ibadan railway on 7 December 2020.^[9]

Set composition[]

China Railway[]

References[]