The blade for an axial-flow impeller may be fixed, or adjusted, about its radial axis relative to the impeller hub. It has a limited freedom of swivel motion about an axis at right angles to its radial axis. A damping element is arranged inside the blade and extends radially outward from the blade root, where it is held in a recess provided in a bolt. The blade is movable about the bolt, the movement being limited by the damping element and the contour of the recess. The bolt is fixed relative to the impeller hub.
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