Japan’s new N700S Shinkansen (bullet train), which entered service on the Tokaido Shinkansen line between Tokyo and Osaka on 1 July 2020, runs on high-performance bearings from NSK.
The N700S is the first completely new Shinkansen design from the Central Japan Railway Company for 13 years. The ‘S’ suffix stands for ‘Supreme’, signifying the progression in design, technology and comfort since the original N700 was launched back in 2007.
High-performance bearings from NSK can be found in the gearbox, axle and traction motor assemblies, underpinning the train’s no-compromise focus on safety, stability, comfort and environmental performance.
The railway is a demanding environment, combining heavy use with the need for components to be utterly reliable and a no-compromise stance on passenger and public safety. Bearings that are used for railway applications contribute directly to safe operation, so high reliability is key, as is the ability to support elevated speeds, improved energy efficiency and reduced maintenance requirements.
The demands placed on railway bearings are especially apparent in bullet trains, which transport large numbers of passengers at high speeds over long distances. Applications of this type call for highly efficient and durable bearings, along with meticulous quality control at all stages of production.
Gearbox
The N700S is the first Shinkansen to replace helical gears with herringbone gears, which offer increased reliability and reduced noise. Gearbox bearings are subject to intense shocks and vibration, so having a long operational life under these conditions is a priority.
NSK has been supplying tapered roller bearings for helical gears in bullet trains for decades. Drawing on this experience, the company designed a special flanged cylindrical roller bearing for the herringbone gears in the N700S that deliver longer life, generate less heat and require reduced maintenance, compared with the previous generation of product.
In addition, the gearbox bearings used on the N700S have improved seizure resistance, which has been achieved by optimising the design of areas that do not contact the flange face. A high-strength machined brass cage, optimised with NSK’s proprietary R-pocket technology, reduces internal stress in the cage structure.
The NSK cylindrical roller bearings used in the N700S gearbox provide longer life with reduced maintenance.
Axles and motors
For the axles, the NSK double-row tapered roller bearings used in the previous Shinkansen have been further improved to deliver even higher reliability and reduced maintenance costs. Lower heat generation leading to longer life is a particular attribute.
NSK cylindrical roller bearings and deep-groove ball bearings used in the traction motors feature outer rings that are plasma-sprayed with a ceramic coating. This increases reliability by preventing electrolytic corrosion, an unwanted side-effect that occurs due to the transfer of electrical current through the inside of uninsulated bearings.
NSK, founded in 1916 and today employing 31,000 people worldwide, has been supporting the advancement of the global railway industry since the company first became involved with the sector in 1932. Bearings from NSK are trusted for their world-class safety, high-speed performance, high reliability and efficiency.
On the railway, the company’s products are used by high-speed rail operators throughout Europe. Close ties with partners in the European OEM and aftermarket sectors help create products that bring about notable advances in this important industry.
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