Abstract: A featherable propeller assembly for fitment to a drive shaft has a blade carrying assembly which is carried by a hub assembly. The blade carrying assembly is rotatable relative to the hub assembly within relative limits of rotation. Blades are pivotally mounted on the blade carrying assembly. The relative rotation of the hub assembly and blade carrying assembly provides for different positions of respective stop abutments, thus allowing the blades to assume each of the following conditions: (a) a forward drive condition under a forward drive rotation of the shaft; (b) a feathering condition when not under drive from the shaft where the blades are substantially free to move into an orientation which is aligned with the flow of water past the propeller; and (c) a reverse driving condition under a reverse drive rotation of the shaft.

Abstract: The invention consists in a centrifugal disintegrator, primarily for producing small particles of rock for use on roads, wherein a rotor with a vertical spindle is fed axially with stones which it flings into a housing. Stones, broken and unbroken, are arranged to be retained in the rotor and in the housing as wearing surfaces. Stray stones are deflected from damaging impact with the material of the machine of the machine by the placement of surfaces. Metal parts which cannot be so protected are fabricated of wear-resistant material and are replaceable.