The present invention is directed to propeller shaft liners of the type disclosed in Rowland et al U.S. Pat. No. 2,751,765. Liners of this type are customarily manufactured by convolutely winding an outer layer or ply of corrugated paper upon a wound paper tube with the outer or envelope diameter of the corrugated outer layer slightly exceeding the internal diameter of the hollow propeller shaft into which the liner is to be inserted. When the tube is inserted into the shaft, the corrugations of the outer layer are compressed against the inner wall of the shaft and are thus capable of absorbing and damping propeller shaft vibrations.
The wrapping or winding of the final layer of corrugated paper on the exterior of the liner tube requires specialized equipment for handling the corrugated strips during the winding operation, and the relatively fragile corrugations exposed on the exterior of the tube require some care in handling operations prior to and during the insertion of the liner into the shaft. Optimum vibration damping characteristics will be achieved when the liner is in firm, uniform centered engagement with the tube over the entire external surface of the liner.
The present invention is especially directed toward the construction of a propeller shaft liner which does not employ an outer layer of corrugated material, but instead employs a smooth paper tube having a relatively small number of relatively deep axially or helically extending indentations in its outer surface, the indentations being of such a depth as to form corresponding ribs in the interior surface of the liner.