Extension shaft sealing structure of high-power speed reducer

A high-power speed reducer output shaft sealing structure relates to the technical field of speed reducers and comprises a box body, an output shaft, a through cover and a plurality of oil retaining rings, a bearing hole is formed in the outer wall of the box body, and a bearing is installed at the inner end of the bearing hole; a plurality of oil retaining rings are adaptively mounted on the inner wall of the outer end of the bearing hole side by side, an oil seal ring is arranged between the inner wall of the through cover and a shaft body of the output shaft, a convex ring is arranged on the inner cover surface of the through cover, an oil injection hole communicated to an inner cavity of the convex ring is formed in the outer cover surface of the through cover, and the outer edge of the outer cover surface of the through cover is detachably and fixedly connected with the outer edge surface of the outer end of the box body corresponding to the bearing hole; an oil slinger is sleeved on a shaft body of the