GB537140A - Improvements in or relating to variable pitch propellor mechanisms - Google Patents

Abstract

537,140. Variable pitch propellers. HOOVER, W. S. Nov. 6, 1939, No. 29480. [Class 114] The pitch of a propeller is changed hydraulically by a mechanism responsive to variations in the position of a pressure - control valve located within the propeller and controlled also by an electromagnetic device actuated independently of the propeller speed. The root 3 of each propeller blade screws into a sleeve 5 carrying balancing weights 6 and a threaded roller engaged by a worm rotated through gearing by an hydraulic motor 20. The motor comprises fixed abutments 34, Fig. 4, secured to a housing 27, and vanes 33 moved angularly by pressure fluid. This fluid, introduced through a pipe 45 in the propeller hub shaft, and an inlet passage 47 enters a chamber 46 housing a spool-shaped slide valve 49 adapted to control oppositely and simultaneously the inlet passage 47 and a discharge pipe 47a, this latter leading to a discharge pipe 44 located within the inlet pipe 45. Shafts 50 carry centrifugal arms 51 linked to the valve to adjust its position according to the rotational speed of the propeller, but manual adjustment can be effected by actuating a solenoid connected through collector rings 54 to an external switch. The mechanism may also be entirely manually controlled if the valve 49, Fig. 8, is provided with an armature 56 movable by two solenoids 57, 58 controlled each by an external switch. The motor 20 may have a rotatable housing to which the movable vanes are secured, the fixed abutments being to a stationary inner hub. To actuate the motor, the-engine oil-pump delivers to a chamber, kept at a predetermined high pressure, from which the motor is supplied and also a second chamber kept at a lower predetermined pressure this second chamber supplying the engine.