NSK develops and supplies a wide variety of railway bearings for wheelset, drive units, and traction motors. These bearings feature high performance, high reliability, and long periods of maintenance-free service to support rail companies in their mission to provide quick, safe, and dependable transport.

Our bearings have a long history in Japan's Shinkansen bullet trains, from the first 0 series right up to the latest sets. We supply Shinkansen trains with bearings using oil-bath lubrication and grease-sealed bearings.

In addition, our proprietary high reliability tapered roller bearings have a long track record. Because drive units face harsh vibrations, these bearings undergo soft nitriding treatment to increase cage strength and feature specifications that improve seizure resistance on the rib face.

NSK is also highly sensitive to needs in the industry. Trains are getting faster and faster. To maintain reliability at high speeds, we are supplying cylindrical roller bearings with ribs specially designed for drive units that use double helical gears. In addition, we've developed specialized cages with excellent grease replenishment capabilities to meet requests for longer periods without maintenance. Damage caused by electric erosion is another big maintenance issue, yet here too we deliver solutions in the form of ceramic and resin insulated bearings. 

We aim to provide trusted quality in all our products. We continue to be certified by the Association of American Railroads (AAR) and in 2018 obtained ISO/TS22163 (prev. IRIS) certification for business management system requirements for rail organizations.


NSK strives to thoroughly grasp the actual conditions and environments where bearings are used and faithfully recreate these in evaluation testing. We work tirelessly to establish advanced measurement technologies and improve on simulation technologies.

We painstakingly measure the motion of the rollers in cylindrical roller bearings used in actual Shinkansen trains and the distribution of load on the rolling elements when the axlebox is deformed. With these advanced measurements and feedback from the results, we have created sophisticated analysis and design technologies. In the future, we aim to create simulation technology that can accurately reproduce real-world operating conditions.

NSK's technical developments in railways are not limited only to bearings. With safety and value as top priorities, we continue to challenge ourselves to establish and utilize varying technologies in pursuit of bearing condition monitoring systems. By also developing and bringing vibration control actuators to market, we contribute to a smoother ride by reducing the sway of railway vehicles during operation.

Operating conditions: high radial and axial loads, strong passage of current

Traction motor bearings in rail transport have to be powerful, environmentally friendly and cost-effective. The high weight of rail vehicles and long, maintenance-free operating hours have to be taken into account to guarantee a high degree of reliability and safety. Apart from reducing the weight of the drive train, traction motors in rail transport are subjected to high radial and axial loads as well as the possibility of a strong passage of electrical current and high speeds. In order to meet these requirements, NSK has developed insulated bearings with a ceramic coating and high-strength cages.
Both Cylindrical Roller Deep Groove Ball Bearings have proven themselves in traction motors for rail vehicles since they are ideal for high speeds and loads and are easy to install and dismantle.

Insulated Bearings for Traction Motors – Ceramic coating & Insulated Bearings for Traction Motors – PPS coating

Traction motor bearings often fail on account of damage caused by the passage of current (electro-pitting). To prevent electro-pitting, NSK has developed insulated bearings with a ceramic coating and PPS resin coating. Both of the above solutions provide a high insulating resistance of over 100Mohms with a breakdown voltage in access of 4KV.
High-strength cages were designed to absorb the loads that occur, such as vibrations. Spherical roller ends and bevelled ribs increase the thrust load capacity, and the high quality along with long service life guarantee the safety and reliability of the traction motors.

Railway, Traction Motor

Operating conditions: radial shock loads and axial loads through swaying movement

Wheelset bearings are subjected to not only radial loads through rail joints and points but also dynamic and static radial loads due to the weight of the vehicle. What’s more, they have to withstand axial loads caused by swaying movements and curves. Since wheelset bearings are subject to this complex combination of loads, both the dimensions of the axle journal and bearing housing as well as the complex load conditions are taken into account during their design.

Rail transport is international. What this means for wheelset bearings is that they are used in a wide variety of conditions such as dirt, moisture and ambient temperatures in different countries. NSK offers wheelset bearings with corresponding sealing solutions as well as different lubricants for these requirements. Tapered Roller Bearings, Spherical Roller Bearings and Cylindrical Roller Bearings are particularly suited for use in wheelsets.


Sealed-Clean Rotating end Cap Tapered Roller Bearings for Wheelsets & Cylindrical Roller Bearings for Wheelsets

Sealed-Clean Rotating end Cap Tapered Roller Bearings can be ideally integrated to adjacent components and are fitted with innovative seals and end caps to prevent the escape of grease and ingress of water. Common bearing problems can be avoided in this way and maintenance intervals can be prolonged to match the operating life of the wheels themselves. Since axle bearings that come into direct contact with the axle have to be designed for difficult conditions, NSK's Taper Roller Bearing Units are an ideal solution: thanks to their high quality, they offer an outstanding performance, a long service life, are easy to handle and suitable for high speeds. NSK's new Cylindrical Roller Bearings have been specially designed to save weight, being a compact space saving design and can operate at high speeds under oil lubrication.


Railway, Wheelset, Drawing

Sealed-Clean Rotating End Cap Tapered Roller Bearings

Sealed-Clean Rotating End Cap Tapered Roller Bearings: They offer outstanding performance, durability and ease of handling.  >>

Insulated Bearings for Traction Motors - PPS

PPS-resin coating insulated bearings developed to prevent electric pitting  >>

Insulated Bearings for Traction Motors - Ceramic

Ceramic coating insulated bearings developed to prevent electric pitting  >>

High Temperature Sealed Deep Groove Ball Bearings

Specially created to run in a contaminated environment, and under high temperatures, up to 150°C.  >>

Cylindrical Roller Bearings for Wheelsets

High-speed capability, easy maintenance and ability to either allow or restrict axial movement. >>

Deep Groove Ball Bearings


CAD Drawing
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