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Proceedings Paper

Improving the service life of the 100-meter Green Bank Telescope azimuth track
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Paper Abstract

The NRAO Green Bank Telescope (GBT), located in Green Bank, West Virginia, is supported by 16 steel wheels which rest upon a composite steel and concrete Azimuth Track, 210 feet (64 meters) in diameter. From the start of observing in February 2001, the Azimuth Track design presented an operational problem for NRAO. By the spring of 2001, slippage of the top plate on the base plate was causing hold-down bolt failures. In July 2002, wear between the top and base plates (fretting) had become evident around the entire track circumference. NRAO engineers took immediate action to reduce both the track slippage and wear problems. But in January 2003, cracks were discovered in two adjacent top plates; by 2006 the top plates were cracking at a rate of almost one a month - an alarming rate given the design service life of 20 years. This paper will summarize the engineering analysis efforts that were subsequently conducted to assess the root cause of the GBT track degradation problem. We will also discuss a trial modification section that was installed in June 2004. Finally, we will discuss the design solution that was developed to remedy the track performance problem.

Paper Details

Date Published: 10 July 2008
PDF: 12 pages
Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 701238 (10 July 2008); doi: 10.1117/12.784935
Show Author Affiliations
Arthur Symmes, National Radio Astronomy Observatory (United States)
Robert Anderson, National Radio Astronomy Observatory (United States)
Dennis Egan, National Radio Astronomy Observatory (United States)

Published in SPIE Proceedings Vol. 7012:
Ground-based and Airborne Telescopes II
Larry M. Stepp; Roberto Gilmozzi, Editor(s)

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