Progressive shear assemblies

Abstract

A progressive shear assembly includes a hub configured for coupling to the output, the hub including a hub drive sleeve and at least one torque transfer lug on the hub drive sleeve. A drive adaptor may be configured for coupling to the drive. The drive adaptor may include an adaptor shaft disposed in the hub drive sleeve of the hub. The adaptor shaft may have an aft shaft end and a fore shaft end and tapering from the aft shaft end to the fore shaft end. At least one adaptor lug may be provided on the adaptor shaft. The at least one adaptor lug may have a substantially non-uniform width from the aft shaft end to the fore shaft end of the adaptor shaft. A tensile spring may be formed by selected ones of a plurality of substantially incompressible shear members and a plurality of substantially compressible compression members disposed adjacent to the adaptor shaft between the at least one adaptor lug and the at least one torque transfer lug. The at least one adaptor lug on the adaptor shaft of the drive adaptor may pre-load the selected ones of a plurality of substantially incompressible shear members and a plurality of substantially compressible compression members in conical compression. Shear assembly sleeves deployable between a propeller adaptor shaft of a drive adaptor and a propeller hub drive sleeve of a propeller hub are also disclosed.