Contact in Wheel-Rail Systems for Large Radio Telescopes:A Review

Increasingly higher pointing accuracies are required of large telescopes.When wheel-track systems are deployed in the azimuth adjustment mechanism of large radio telescopes, it is vital that the influence of inaccuracies within such systems on pointing errors, as well as the effects of erosion on such inaccuracies, be studied and understood.This paper presents an analysis of the advantages and shortcomings of the wheel-rail type pedestal, as well as a general review of wheel-rail systems and related pointing calibration methods.Contemporary wheel-rail systems for large radio telescopes are prone to many problems, such as frictional wear, fatigue cracks, and irregularities.Methods by which such problems are mitigated and/or circumvented currently consist mainly of modifications to the structure, material, and production processes of the track.By comparing the characteristics of common wheel-rail systems and referencing results of previous studies on the orbit traffic and crane, the classical theory of wheel-rail contact and its limitations were introduced, and the main outstanding challenges for future research in this field were summarized.