BYLINE: Norihiko Yoshie (left) and Junichui Ito (right)

ROLLING STOCK engineers from JR Central and JR West are confident that they will be able to achieve lower capital and running costs with the next generation of shinkansen train. Due to roll out in September, the 16-car N300 prototype, forerunner of a fleet of trains to be known as Series 700, has been developed jointly by both companies.

Heading the development team are Junichi Ito, Manager of the Rolling Stock section of JR Central’s Shinkansen Operation Division, and Norihiko Yoshie, Chief Engineer in JR West’s Rolling Stock Department. The project began in July 1996, and it was formally announced two months later when design work got under way. Ito and Yoshie said the target date for completion of the prototype set is September this year.

The N300 design will reflect the experience and expertise that the two companies have amassed in the last two years - JR West with the WIN350 research train and Series 500, and JR Central with the Series 300 Nozomi units and the experimental 300X trainset that set the Japanese speed record of 443 km/h on July 26 last year.

More comfort, less weight

The aim of the N300 programme is to lift standards of passenger comfort and reduce costs without increasing weight in relation to Series 300. Part of the higher comfort objective has translated into achieving lower interior noise levels, and Ito said the target was to keep noise to the same level as in locomotive-hauled coaches. This will be achieved by providing better insulation and cutting noise levels at source.

Use of the latest bodyshell construction techniques is expected to offer good sound insulation. The shells will be formed of hollow extruded aluminium sections filled with resin foam; thickness of the aluminium will be reduced to 2mm compared with 3 to 3·5mm in similar applications in Europe. The technique has also been chosen to reduce the number of manufacturing processes.

The body cross-section of the N300 will be slightly less than Series 300 - 10·9m2 compared with 11·1m2 - helping to reduce running resistance.

Use of IGBT converters in the traction package will help cut interior noise levels at the source below the floor, and both the transformer and traction motor design are intended to achieve similar objectives.

Achieving low exterior noise levels is also vital to ensure that the train is accepted by Japan’s noise-conscious population. In terms of exterior noise levels, the two companies’ extensive work on front end design has led to the choice of an 8·5m nose compared with 6m for Series 300 and 15m for Series 500, which is designed to be able to run at 320 km/h. Maximum speed of the N300 has not been finally settled, but it is likely to be 270 km/h on the Tokaido Shinkansen because of the relatively small radius curves and perhaps 285 km/h on the Sanyo Shinkansen.

The N300 has been designed to be easier to maintain than other builds of shinkansen train. For example, the underfloor equipment modules have been designed so that everything can be inspected and components replaced from one side only. Maintenance requirements will be advised to depots and workshops by an ’intelligent train’ diagnostics system.

Whereas Series 300 had 10 powered and six trailer cars, the N300 will have 12 motored cars and four trailers; three motored cars and one trailer form an electrical unit, but pantographs are only fitted on cars 5 and 12. Transformer output will be increased from 3000 kVA to 4000 kVA, but thanks to use of aluminium instead of copper windings, and also the low heat-loss design with IGBTs, the transformer weight will be cut by almost 3 tonnes.

The larger number of powered vehicles means that a higher dynamic braking force is available from the traction motors. This means that the number of eddy current disc brakes can be reduced. Eddy current disc brakes were successfully pioneered on Series 100, and they were also fitted to Series 300, with two eddy current brake coils on each trailer axle. On the N300 there will be just one, allowing another reduction in weight.

JR Central and JR West plan to order their own fleets of Series 700 sets; Ito and Yoshie expect the combined fleet size to be similar to that of Series 300, which when production ends in 1998 will total 61 sets. In terms of cost, they expect the price to be similar too; Series 300 costs about ´4bn a set. o

CAPTION: Artist’s impression of the Series 700 prototype

Further improvements in design will reduce noise generation, improve the passenger environment, and cut maintenance costs