Performance of bearings in high speed applications
Tapered roller bearing unit came out in the 1950s and was originally used in American trucks to bearings replace sliding bearings. The American Association of railroads (AAR) has formulated standards for this kind of bearing and stipulates that carburized steel shall be used for inner ring, outer ring and roller.
In high-speed and ultra-high-speed applications, carburized steel and fully quenched steel can be used depending on the specific application requirements. In general, fully quenched steel is cleaner than carburized steel and has less impurities. In many applications, fully quenched steels perform better.
In the application of locomotives, multiple units, passenger cars, urban rail cars and freight cars with closed axle boxes, fully quenched steel is generally used.
Speaking of this, it may reveal one of the bearing black technologies - high-end materials science. Brother, do you know that the Swedish people play metal more smoothly than other European countries combined. Sorry, most of the elements on the periodic table were made by Swedish scientists. Like this high-speed bearing, the most difficult to overcome is not only the design, but the metal material. Inclusions in metallic materials are easy to lead to subsurface metal fatigue in advance during bearing operation. Therefore, the purity of domestic high-end steel products is slightly lower than that of imported products. However, domestic truck bearings have basically been made of steel, but the high-speed railway is not.
The axle load is also generally defined.
·Light rail car: 14 t · high speed car: 17 t (New) · heavy haul metro car and EMU: 18 t · locomotive and freight car: less than 25 t · heavy haul freight car: 32 t to 40 t
At present, the axle load of domestic high-speed railway is generally required to be less than 20t, so the requirements are not very harsh,
As for the wheel diameter, you generally have a default value.
·High speed vehicles, multiple units and passenger cars: 750 to 950 mm
·Locomotive: 1000 to 1300 mm
·Truck: 900 to 1000 mm
·Piggyback transport vehicle: 350 to 450 mm (transport trailer, semi-trailer or bearings container vehicle -
