Improvements in labyrinth seals

895,467. Axial-flow compressors; turbines; labyrinth packing. ROLLS-ROYCE Ltd. July 8, 1960 [July 31, 1959], No. 26399/59. Classes 110 (1), 110 (3) and 122 (5). In a gas turbine including an axial flow compressor 11 air bled from the compressor to act at 2 on the compressor rotor 1 and reduce the end thrust on the rotor bearing 3 passes through two labyrinth seals in succession, the parts of the seals being so arranged that conditions, such as rapid turbine acceleration, which produce an increase in the gap clearance of one seal will also produce a corresponding decrease in the gap clearance of the other seal. The seals are formed by radially inwardly and radially outwardly directed ribs 7 and 9 on a part 5 secured to the compressor outlet easing 16 co-operating respectively with ribs on parts 4 and 6 attached to the compressor rotor. Any tendency of the part 5 to " grow " under rapid acceleration and increase the gap between parts 4 and 5 will produce a corresponding decrease in the gap between parts 5 and 6 and thus maintain the air pressure at 2 substantially constant. Specification 622,369 is referred to.