GB590457A - Improvements in or relating to pitch changing mechanisms for propellers - Google Patents

Abstract

590,457. Hydraulic motors. UNITED AIRCRAFT CORPORATION..Jan. 6, 1943, No. 281. Convention date, Jan. 15, 1941. [Classes 69 (ii) and 135] [Also in Group XXXIII] The blade-pitch of a propeller is changed in both directions by means of a rotatable fluid motor which can be reversed by two separate and independently operating fluid pressure controlled means. In the form shown, a hydraulic swash-plate motor 52 is supplied with liquid from an enginedriven pump 38, under the control of a valve 34 operated by a speed governor 36, the liquid passing through a valve 45. For feathering purposes, the motor 52 is supplied with liquid from a separate motor-driven pump 41, the pressure from which moves the plunger 46 of the valve 45 to cut off the pump 38. The motor 52 has a drive shaft 90 with diametricallyopposed extensions 100, 102 between which is disposed a cam on the pitch-changing gear by means of which the blades are locked in position except when the shaft 90 is rotated to change the pitch.. The pistons 168 and the wobbleplate 170 of the motor 52 have interengaging hook elements to ensure movement in both directions, and the wobble-plate chamber is filled with liquid. The Specification contains details of the pitch-changing gearing between the shaft 90 and gears 142 on the blades 12, stop means for limiting the pitch-varying range, lubricating passages in the hub, and the construction and operation of a central rotary plug valve 166 for the motor 52.