GB539064A - Improvements in devices for controlling in flight the variation of the pitch of a variable pitch propeller - Google Patents

Abstract

539,064. Toothed gearing. RATIE, P. J. P. April 14, 1939, Nos. 11410 and 11411. Convention dates, Dec. 28, 1938, and March 29, 1939. [Class 80 (i)] [Also in Group XXXIII] Epicyclic gear for varying the pitch of a propeller comprises a casing 3 and a cap 4 secured to the boss of the propeller, the cap having teeth 4a and the casing containing a loose gearring 5 with like teeth. These teeth gear with sets of equal planet pinions 11, 8 respectively mounted on the same shafts and separated by rollers bearing on an external race between the casing and cap, and an internal race. The ring 5 engages pinions 6 the shafts of which mesh with the shafts 7 of worms meshing with wormwheels 7a on the roots of the propeller blades. The planet pinions respectively engage gearrings 12 on a bush 15 and 13 on a ring 32, which are secured to toothed rings engaging a shaft 41 with differing gear ratios. Rotation of this shaft rotates the primary gears 12, 13 to an unequal extent and so gives the gears 5, 4a a relative rotation; whence the blades driven by the gear 5 are tilted on the boss. Fig. 7 shows the ring 38 provided with sets of internal and external teeth, the shaft 41 being shifted axially to engage either of them at the same time as the gear 15a and so give a quick or slow rate of change of the tilt; alternatively, the ring 38 has internal teeth only. The Specification as open to inspection under Sect. 91 describes apparatus in which one of the primary gears is fixed and the other given a motion, and also apparatus in which the pitches of two coaxial screws are regulated. This subject-matter does not appear in the Specification as accepted.