Three row roller slewing ring has 3seat rings, upper orbit, nether orbit and radial orbit are separated individually, it makes the load of each row of the rollers can be confirmed, so it can undertake all kinds of different load simultaneously and it's carrying capacityis the biggest among four models, one more thing, the axial and radial size are rather large to some extent and the structure is vry firm, so it is especially suitable for many heavy duty machines which require bigger diametrer such as bucket wheel excavator, wheeled crane, shipyard crane, heavy duty crane and so on.