GB541600A - Improvements in ship's propellers - Google Patents

Abstract

541,600. Screw propellers. CHANT, J., and HOAR, T. P. July 30, 1940, No. 12317. [Class 114] With the object of preventing corrosion of the blades of a ship's propeller due to galvanic action, the blades are mechanically linked to the propeller shaft by means of bodies of rubber or like electrically insulating material, which are so disposed that the torque is transmitted from the propeller shaft to the blades by subjecting the rubber &c. bodies to compressive forces only, i.e. without imposing upon them any tensile or shearing forces. As shown the propeller blade with hub P is mounted upon but electrically insulated from a metallic liner B which is keyed to the shaft S by a key K so as to rotate therewith. The insulation comprises a rubber sleeve I<SP>1</SP> and rubber annuli I<SP>2</SP>, I<SP>3</SP> spacing the hub P from the liner B, flange F thereon, and nut N<SP>1</SP> on the liner. For the transmission of the torque pins D extend from the flange F into recesses on the hub P lined with insulation I<SP>4</SP>, which is thereby subjected to compressive forces only. A lock-nut N<SP>1</SP> and safety pin L secure the whole. Alternatively, projecting pins may. be provided on the hub P to engage lined recesses in the flange F, or co-operating keys and recesses may be provided on the liner B and hub P. Or, in a further modification the blade of the propeller may be separated from the hub P by interposed rubber elements, but connected thereto by bolts passing through rubberlined holes. If desired, the electrically insulating elements may be constituted as fabrics impregnated with rubber or with thermosetting or self-setting resins and adapted to adhere to the surfaces to be electrically insulated.