SHAFT SEAL DEVICE FOR MARINE PROPELLER SHAFT

PROBLEM TO BE SOLVED: To ensure the sealing performance while extending the life of a seal ring by forming primary and secondary annular chambers each between the adjacent seal rings of at least there seal rings axially juxtaposed on a propeller shaft, and connecting an air charging system to the primary annular chamber. SOLUTION: A plurality of guide rings 3 are mounted outward on a stern tube bearing 2, and at least three seal rings 5-7 are nipped each between the adjacent guide rings 3 at a rate of one. A sleeve 11 is fitted onto a propeller shaft 10 so as to pierce the seal rings 5-7. A primary annular chamber 14 is formed between the seal rings 5, 6 close to the outside, and a secondary annular chamber 15 is formed between the seal rings 6, 7 closer to the stern tube, an air charging system 18 set on the inside is connected to the primary annular chamber 14 through a feed pipe 17, and a drain tank 20 is also connected through a drain recovering pipe 19. On the other hand, an oil feed pipe 21 is connected to the secondary annular chamber 15.