526,167. Air screws. HIVES, E. W., BARRINGTON, T. B., and RUBBRA, A. A. March 4, 1939, No. 7153. [Class 114] An air-screw hub is made in two parts, 11, 14, the former consisting of a sleeve 11 surrounding the air-screw shaft 10, and the latter having hollow stub portions 15 in which the blades are secured. The part 14 slides over the sleeve part 11 and is secured thereto by bolts 21, 22, passing through radial and axial flanges 17, 18, respectively. The parts 11, 14, may be keyed together, and the bolts 22 may be replaced by taper pins retained in position by a shrunk-on surrounding ring. Specification 455,044 is referred to.