Archive for June 4th, 2017

Navy Capstans and the Development of Specialized Friction Coefficients

Sunday, June 4th, 2017

    We’ve been talking about pulleys for awhile now, and last week we introduced the term friction coefficient, numerical values derived during testing which quantify the amount of friction present when different materials interact.   Friction coefficients for common materials are routinely presented in engineering texts like Marks’ Standard Handbook for Mechanical Engineers.    But there are circumstances when more specificity is required, such as when the U.S. Navy, more specifically the Navy Material Command, tested the interaction between various synthetic ropes and ship capstans and developed their own specialized friction coefficients in the process.

Navy Capstans and the Development of Specialized Friction Coefficients

Navy Capstans and the Development of Specialized Friction Coefficients

   

    Capstans are similar to pulleys but have one key difference, they’re made so rope can be wound around them multiple times.   When the Navy set out to determine which synthetic rope worked best with their capstans, they did testing and developed highly specialized friction coefficients in the process.  This research was at one time Top Secret but has now been declassified.   To read more about it, follow this link to the actual handbook:

https://archive.org/stream/DTIC_ADA036718#page/n0/mode/2up

Copyright 2017 – Philip J. O’Keefe, PE

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