Self-lubricating lengthened linear bearing

The utility model discloses a self-lubricating lengthened linear bearing which comprises a bearing sleeve, a retainer is arranged in the bearing sleeve, a placing frame is arranged on the outer surface of the retainer, balls are arranged in the placing frame, a sealing ring is arranged on the inner wall of the left end of the bearing sleeve, and a sealing ring is arranged on the inner wall of the right end of the bearing sleeve. Oil injection openings are symmetrically formed in the end, opposite to the sealing ring, of the bearing sleeve, first springs are arranged in the oil injection openings, and check blocks are arranged at the top ends of the first springs. Through the arrangement of the sealing ring, the first spring, the second spring, the check block, the oil guide pipe, the connecting opening, the third spring and the abutting block, the first spring can clamp the sealing ring in the gap between the left end of the bearing sleeve and the retainer, the sealing ring can be kept not to deform, the chec