Balance weight anchor set up: a review of current practice vs established theory

Auto tensioned contact systems typically employ a simple weight system with mechanical amplification (eg: pulley wheels) to apply a constant tension to the overhead conductors for the prescribed temperature range. The weight system should be designed to accommodate the expansion and contraction of the system resulting from temperature fluctuation. Balance weight setting ‘theory’ is typically a simple calculation governed by the geometry of the system, the conductor temperature at the time of setting and the material property of the conductor. Creep in the conductors also affects the geometry. Techniques to mitigate the effect are reviewed and appraised. The study researched current practice and identifies where installation methods are not delivering the intent of the theory. Setting methods are examined. Typically, ambient temperature is used by installers and maintainers as a convenient substitute for actual conductor temperature. The error this introduces is assessed, and a potential ‘rule of thumb’ is sought to allow this practice to continue. Compatibility of weight system design with other elements of system design (eg: anchor height) is reviewed and appraised. Seasonal adjustment of the weight system at particular locations is, anecdotally, known to be employed where anchor heights are thought to infringe the required travel of the weights. This practice is reviewed and discussed. This paper reconnects long established theory with present day practice. It offers improvements to current practice that ultimately reduce the risk of dewirement occurring in extreme temperatures.

Media Info

  • Pagination: 10p. ; PDF
  • Monograph Title: Maintaining the momentum: CORE 2016: conference on railway excellence, 16-18 May 2016, Melbourne, Victoria, Australia

Subject/Index Terms

Filing Info

  • Accession Number: 01636842
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: May 30 2017 3:28PM