Assembled yoke of the 140-foot (43-meter) telescope on the ground in Green Bank, West Virginia during its construction in the 1960s. The yoke supports the telescope’s tilt axis and keeps the giant telescope balanced as it arcs across the sky. Pacific Crane and Rigging Company completing the final assembly of the yoke components (made by Sun Shipbuilding) to the hub section (built and machined by Westinghouse). The hub section consists of a 3.5% nickel steel casting welded to 6 inch, A 201 plate for a finished machined weight of 190 tons. When completed the entire yoke is a single weldment. Its completed weight is 1,125,000 pounds of steel to which are added 1,300,000 pounds of counterweight concrete and portable ballast rocks in the tubular, bottom sections.