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

Arthur Symmes; Robert Anderson; Dennis Egan

doi:10.1117/12.784935

10 July 2008 Improving the service life of the 100-meter Green Bank Telescope azimuth track

Arthur Symmes, Robert Anderson, Dennis Egan

Proceedings Volume 7012, Ground-based and Airborne Telescopes II; 701238 (2008) https://doi.org/10.1117/12.784935
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

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.

Citation Download Citation

Arthur Symmes, Robert Anderson, and Dennis Egan "Improving the service life of the 100-meter Green Bank Telescope azimuth track", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 701238 (10 July 2008); https://doi.org/10.1117/12.784935

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