Three-row roller type slewing bearing

The utility model relates to a slewing bearing with three rows of rollers, and relates to the field of slewing bearings, the slewing bearing comprises an outer ring, an inner upper ring and an inner lower ring, the bottom wall of the inner upper ring is attached to the top wall of the inner lower ring, the inner upper ring and the inner lower ring are coaxially arranged in the outer ring, the inner upper ring is provided with an oil injection hole, and the inner lower ring is provided with an oil outlet. An oil injection hole is formed in the inner lower ring, the oil injection hole is communicated with a gap between the outer ring and the inner upper ring, an upper plugging assembly used for automatically plugging the oil injection hole is arranged in the oil injection hole, an oil inlet hole is formed in the inner lower ring, and the oil inlet hole is communicated with a gap between the outer ring and the inner lower ring; a lower plugging assembly used for automatically plugging the oil inlet hole is arran