Provide (1) 40-ton and (1) 30-ton overhead electric traveling trolley to replace the existing trollies in the anechoic chambers at a Naval Air Warfare Center (NAWC) Aircraft Division, for the Navy Crane Center. The trolley units are used to hang heavy loads (some valued over $100M) statically for a long period of time after the loads are lifted to a required height. Naval Air Warfare Center personnel are required to work around and briefly under the suspended load to hook up equipment. The new trolley units were designed with single failure proof features and design factor that provide maximum safety against inadvertent load lowering. Single failure proof features include: -Hook design safety factor of 6:1 on yield -Dual load path wire rope reeving system -Disc brake acting directly on the wire rope drum -Broken shaft detection system to detect hoist drive train issues -Unbalanced load limit detection system at the equalizer bar -Drum pawl engagement system to hold the load Removal of obsolete trolleys and installation of the new trolleys was extremely difficult.