Detachable propeller blade

Claim 1

A propeller to be connected to the end zone of a drive shaft comprising: an annular, axially symmetrical casing to be axially arranged in spaced relation about the drive shaft end zone, said casing having a plurality of circumferentially equi-spaced holes therethrough, the center lines of said holes being coplanar in a transverse plane located in the mid-zone between the ends of said casing, each hole having an inwardly and an outwardly facing seat thereabout defined in the surface of the casing; a plurality of propeller blades, each having a proximal end with a stepped threaded shank, the shank of each blade extending through one of the holes of the casing, said stepped shanks being of a common length and each having a first threaded length of reduced diameter and a second threaded length of greater diameter, said second threaded length being intermediate the first threaded length and the adjacent end of the blade, said second threaded length being of an axial length greater than the radial thickness of the casing, one of the threaded lengths of said stepped shank being characterized by a right-hand thread and the other of said threaded lengths being characterized by a left-hand thread; an inner hub on the end zone of the shaft and within the casing, said hub having an inner and an outer axially facing end, and a plurality of radially extending spacer portions; means to connect the spacer portions to the casing; means to connect the hub to the shaft; and a plurality of spaced radial recesses in the surface of the hub, each characterized by a radial center line in said plane and one of said holes being between each spacer; each of said recesses defining a hole to receive the inner end of one of the blades and having a flat radially facing surface which opens toward the inner end of the hub; a first nut on the larger diameter portion of the shank oF each blade tightened to secure the blade to the casing and securing the blade in a predetermined pitch attitude with respect to the casing; and locking means for the blade comprising a second nut on the reduced diameter length of the shank and in tight engagement with the surface of the flat of the recess of the hub.