Rotary blade propeller with protection against overload

Claim 1

A CYCLOIDAL PROPULSION PROPELLER HAVING A BODY, A PLURALITY OF BLADES PIVOTALLY MOUNTED ON SUBSTANTIALLY PARALLEL AXES ON SAID BODY IN CIRCUMFERENTIALLY SPACED RELATION THEREON, A CONTROL MEMBER SUBSTANTIALLY CENTRALLY LOCATED IN SAID BODY OPERATIVELY CONNECTED WITH SAID BLADES AND MOVABLE RELATIVE TO THE BODY FOR ADJUSTING THE PITCH OF THE BLADES WHEREBY THE PROPELLER WILL DEVELOP PROPULSIVE EFFORT, CONTROL MEANS CONNECTED WITH SAID CONTROL MEMBER FOR ADJUSTING THE POSITION THEREOF IN SAID BODY RELATIVE TO A CENTRAL NEUTRAL POSITION, SAID CONTROL MEANS COMPRISING TWO ANGULARLY RELATED SERVOMOTORS CONNECTED TO SAID CONTROL MEMBER, EACH SAID SERVOMOTOR COMPRISING, A HYDRAULIC SYSTEM INCLUDING CONTROL VALVE MEANS HAVING FEEDBACK LINKAGE MEANS CONNECTED TO SAID CONTROL MEMBER REVERSIBLY CONTROLLING THE SUPPLY OF FLUID TO THE RESPECTIVE SAID SERVOMOTOR, AND RELIEF VALVE MEANS CONNECTED IN SAID HYDRAULIC SYSTEM OPERABLE FOR EXHAUSTING FLUID FROM THE PERTAINING SAID SERVOMOTOR WHEREBY DEFLECTION OF SAID CONTROL MEMBER IS PERMITTED UPON IMPACT TO A BLADE UPON DEVELOPMENT OF A PRESSURE THEREIN EXCEEDING THE PRESSURE ENCOUNTERED IN NORMAL OPERATION OF THE PROPELLER.