Talking About Shaft
The polar shaft for the 140-foot (43-meter) telescope in Green Bank, West Virginia is one of two axes for our 200-foot tall telescope. This shaft is a machined, 3.5% nickel steel casting weighing 40 tons, welded to a tubular, rolled plate straight section weighing 90 tons, which in turn is welded to a 3.5% nickel conical transition casting machined to 85 tons. The maximum length is 55 feet and diameter is 12 feet. The world’s largest metal bearing (covered) was bolted to the end using 29 5-inch diameter high strength steel bolts to become the rotational bearing for the telescope. It took six hours to carefully lift and place this 555-ton shaft into its casing on the concrete pedestal.
Credit: NRAO/AUI/NSF
