GB412434A - Improvements in and relating to aerial propellers with variable pitch - Google Patents

Abstract

412,434. Variable pitch screw propellers. AIVAZ, J., 87, Rue de Monceau, Paris. Feb. 14, 1933, No. 22350. Divided on 411,601 under which a Specification was laid open to inspection under Sect. 91 of the Acts, Aug. 18, 1933. [Class 114.] A variable-pitch screw propeller wherein pitch variation is effected by power such as that obtainable from the propeller shaft has as its varying gear sets of screw and nut mechanism disposed around the axis of the propeller each set comprising an endwise screw member which is directly connected to a propeller blade and preferably by a rack and pinion mechanism. The main screw operating mechanism has end clutches whereby the gear may be automatically disconnected at the two end positions of its motion. The shaft 7 is adapted to be driven by epicyclic gear from the propeller shaft and controlled by braking mechanism and has keyed thereto flanges 9 with ratchet teeth 8, these flanges being constrained inwardly by helical springs. Freely mounted on the shaft is a screw 2 also having end flanges with corresponding ratchet teeth 8. Mounted on the screw is a nut member 3 having on one side rack teeth adapted to engage a pinion 6 on the root of the blade 1. Normally one of the ratchet teeth will be in engagement and upon application of the brake of the epicyclic gear, the screw and therefore the nut receive motion and communicate it to the blade. When the nut has reached the end of its travel, projections thereon abut against the corresponding flange 9 and slide it endwise so that its teeth come out of engagement from those on the screw which is thereby disconnected. Specification 411,601 is referred to.