Bearing design rules diameter coefficients
Special tapered roller bearing units have been developed for Chinese freight car bogies to meet Chinese railway standards. The bearing unit is fitted with labyrinth lip seals on both sides, as well as plastic steel spacers and plastic steel cages. These tapered roller bearing units (130 x 230 x150) are interchangeable with other tapered roller bearing units used in China. The new generation of Chinese wagons is designed with a 80 t wagon carriage and a speed of 120 km/h, while the previous design rules were 60 t wagon carriages and a speed of 80 km/h.
There is also a speed, 300 km / h, then the wheel end speed will reach 300 km / h, then we calculate the speed coefficient °. Let's assume that the wheel end diameter is about 800mm.
300km/h=5000m/min=83m/s。
Then the angular velocity is about 207.5 radians /s, and the rotational speed is 3360 = 1980 RPM. (This is not yet the limiting speed).
Then - the size of the general high-speed rail bearing is: 130 in the middle× 240× 160 × 160.
Then the bearing dm value is, (130 + 240) / 2 = 185mm.
Then the ndm value is about 366300.
So what is this ndm value equivalent to? Therefore, the speed requirement is also a certain pressure.
The problem is that the precision and lubrication requirements of the bearing are relatively high, otherwise it is impossible to achieve such a high ndm value.
