Special Features:

Seawolf class submarine ssn 23 port payload door operating hydraulic cylinder assembly

Properties:

A cap, usually of metal, designed to retain lubricant and excludes foreign matter from bearings. It is normally used as an end closure on items designed to rotate on a shaft,such as a wheel hub, or fit into a housing at the end of a rotating shaft, or the like. Do not use if a more specific name applies. For items mounted by bolt holes, see cover, access.