A device for controlling the pitch of a propeller that is driven by an engine, wherein the propeller is of the type permitting cycle adjustment of the propeller blades, the device comprising:
- a connecting push rod connected to the propeller such that the shifting of the push rod in a first direction changes the pitch of the propeller in a respective first direction of pitch, and shifting of the push rod in the first opposite direction changes the pitch of the propeller in the opposite direction of pitch thereof;
- a servomotor including an axially shiftable first piston connected with the push rod for moving the push rod in the first direction and the first opposite direction as the first piston shifts in a second direction and second opposite direction, respectively;
- the servomotor including first piston shifting means operable for shifting the first piston in its second direction and including second piston shifting means operable for shifting the first piston in its second opposite direction;
- a control valve including a control pin and connected with the first and second piston shifting means such that movement of the control pin in a third direction operates the first piston shifting means and movement of the control pin in the third opposite direction operates the second piston shifting means;
- an adjustment device connected with the control pin for selectively moving the control pin in the third direction and the third opposite direction thereof;
- the adjustment device comprising:
- means for sensing the load on the engine driving the propeller to rotate and for delivering a signal dependent upon the load on that engine;
- a reversing valve connected for receiving the signal from the load sensing and signal delivering means;
- the reversing valve also being connected with the adjustment device;
- the reversing valve having a first condition thereof at which the reversing valve is connected to the adjustment device for causing the adjustment device to move the control pin in the third direction and also for transmitting the load dependent signal to the adjustment device for enabling operation of the adjustment device proportional to the load dependent signal;
- the reversing valve having a second condition thereof at which the reversing valve is connected to the adjustment device for causing the adjustment device to move the control pin in the third opposite direction and also for transmitting the load dependent signal to the adjustment device for enabling operation of the adjustment device proportional to the load dependent signal;
- a wedge pathway member connected with the servomotor first piston for moving therewith;
- the wedge pathway member defining a pathway that is oblique to the pathway traveled by the wedge pathway member as it moves along with the servomotor piston;
- the reversing valve including an operator thereof which rides along the wedge pathway of the wedge pathway member as the wedge pathway member moves with the servomotor piston with respect to the operator riding thereon;
- as the operator rides in a fourth direction along the wedge pathway, the operator shifts the reversing valve to the first condition thereof, as the operator rides in the opposite fourth direction along the wedge pathway, the operator shifts the reversing valve to the second condition thereof.