NSK Bearings: Driving Performance in the Railway Industry

Railways

NSK supplies railway vehicles with a wide variety of bearings for wheel axles, drive units, and traction motors. NSK bearings offer high performance, high reliability, and long periods of maintenance-free service to support rail companies in providing 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 that use oil-bath lubrication and sealed bearings with grease. Since axle bearings are instrumental to train safety, we developed and equipped bearings with condition-monitoring sensors for practical use.

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

NSK is also highly sensitive to changing industry needs. Trains are getting faster and faster—To maintain reliability at high speeds, we developed cylindrical roller bearings with ribs specially designed for drive units that use double helical gears.

For longer periods without maintenance, we developed specialized cages with excellent grease replenishing capabilities. 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.

As proof of our commitment to 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.

Bearings for Traction Motors

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 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. Aside 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 potential for strong passage of electrical current and high speeds. In order to meet these demanding requirements, NSK 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 developed insulated bearings with a ceramic coating and PPS resin coating. Both 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.

Wheelset Bearings

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

Wheelset bearings are subjected not only to radial loads through rail joints but also dynamic and static radial loads due to the weight of the vehicle. Additionally, 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 which means wheelset bearings are used in a wide variety of conditions including dirt, moisture and ambient temperatures. 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 high quality seals and end caps to prevent the escape of grease or ingress of water contaminant. 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. They offer outstanding performance, a long service life, easy handling and are suitable for high speeds. NSK's new Cylindrical Roller Bearings have been specially designed to save weight, with a compact space saving design that can operate at high speeds under oil lubrication.