GB445652A - Improvements in aerial propellers with variable pitch - Google Patents

Abstract

445,652. Screw propellers. WASEIGE, C. R., 62, Boulevard Belle-Rive, Rueil, Seineet-Oise, France. April 30, 1935, No. 12835. Convention date, May 1, 1934. [Class 114] [See also Group XXIX] A variable-pitch screw propeller is provided with two mechanisms of different ratio, one of which provides slow changes up or down and the other rapid changes. The propeller blade 4 is provided at its base with a bevel wheel 9 engaging a bevel wheel 8 on a sleeve common to a spur pinion 7 which engages with the driving pinion 6. The pinion 6 can be driven in forward or reverse direction through gearing under the control of a lever 12. The gearing is driven by an electric motor which rotates with the propeller and which has rings 2 and contact brushes 3 and this motor is capable of being driven at two different speeds. In a modification, blade 4 is secured to a sleeve which carries the actuating bevel 9 and is connected through gearing with a shaft 32 having a pinion 31 adapted to be driven by either of two epicyclic gear trains, one of which provides the slow motion and the other the fast. The two trains are connected by a planet pinion 24 which by the clutch 25 can be coupled or uncoupled. When uncoupled fast changes are provided by braking one of the drums 15, 16. When coupled slow changes are effected by braking drum 17 or 18. A shaft 42 is geared to the drums 15, 16, a friction brake 40 being disposed between the pinions 41, 43, and this shaft drives through a differential the pitch indicator. Hand levers 50, 72 for controlling the gearing are linked through a cam 68 with the throttle of the engine and also by a lever 91 with the controls of a servomotor piston 75 and by a lever 77 which controls a servomotor 52 which operate through rack gear upon the brakes of the epicyclic gearing. Interconnected with this gear are linkages 70 and 60 which are adapted to contact with cams 88 and 65 respectively and so cut out the control when the pitch has been changed to its maximum position. In order that the connection 25 shall be out of position when slow changes of pitch are required, the hand lever 50 is connected through a cam 81 with the striking lever 83 of the grooved collar 84 which affects the clutching mechanism coupling the two epicyclic trains. The valve 76 in the hydraulic circuit is closed when the servomotor 52 is not in action by the rod 77 which is pivotally connected with a lever 79 coacting with a notch in the main control lever. Automatic control of the mechanism in the slow pitch position may be effected by a centrifugal governor 90 which controls the valve gear of the servomotor 75 by means of a lever 91. Its action may be adjusted by regulating the spring 92 through bevels 95 and 96 and this may be connected with a lever 102 on a setting dial by an adjusting cam 99. The adjusting device may also incorporate adjustable stops 105 for determining the two extreme pitch positions. In the event of failure of the engine, the brake-shoe 22 may be applied by the link 111 and cable 110 and the blades brought into a no-pitch position.