1,074,616. Variable pitch propellers. UNITED AIRCRAFT CORPORATION. March 31, 1965, No. 13761/65. Heading B7V. A mechanism for changing the pitch of the blades. (14) of a variable pitch propeller comprises a fluid operated pitch changing motor (18), stop means (20) providing first and second stops (64, 66) for preventing the pitch going below first and second predetermined values, a fluid operated servomotor (80) for actuating the stop means, valve means for controlling the fluid to the fluid receiving chamber (78) of the servomotor (80) to move the latter and a wedge (70) connected thereto which wedge engages a recess in a pivoted cam (62) on which said stops (64, 66) are formed, the wedge 70 moving to a second recess in the cam (62) and allowing the cam to retract so that the piston (17) of the pitch changing motor (18) can pass over the first low-pitch stop (64) to the second lowerpitch stop,. and valve means further controlling the fluid to the servomotor (80) to cause the wedge 70 to be moved from said second recess so that the cam (62) retracts still further to allow the pitch changing motor piston to pass over the second stop (66). This last movement of the pitch-changing motor takes the blades into reverse pitch.
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