NSK develops and sells a wide variety of bearings for use in railway vehicles, including for wheel axles, drive units and traction motors. These bearings feature high performance, high reliability and long maintenance intervals to help support rail companies in their mission to facilitate a safe, fast and reliable arrival at the destination. NSK bearings have a long history in Japan's Shinkansen bullet trains, starting with the first 0 series, right up to the latest N700 series. The company supplies two different types of Shinkansen wheel axle bearings: the grease-sealed type and the oil bath lubrication type. Because wheel axle bearings have a direct impact on train safety, sensor-equipped bearings that monitor the bearings' condition have also been developed, and these have been put into practical use on freight trains. For the bearings used in drive units that are operated in conditions of severe vibration, NSK's proprietary and extremely reliable bearings have been used for many years. The bearings used in the traction motor must also conform to requirements for extended maintenance intervals, and NSK has therefore developed cages that have excellent grease replenishment capability, and also incorporate a fail-safe design. As a result, the company has brought into commercial use bearings with a grease-life more than twice that of conventional models.