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    Discussion in 'The main mechanical design forum' started by Mastino, Mar 29, 2012.

    1. Mastino

      Mastino New Member

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      Hello everybody,
      Maybe someone can help me to solve this engineering problem. How you will see on the photos I need to add this little potentiometer to the big gear. It will give me the information about the position of big gear(the biggest with the hole inside). Off course it is better to instal this potentiometer inside the box, but it can be all so outside.
      So maybe someone has a great idea?:)
      Thank you very much!
      P.S. Sorry for the big size images!
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    3. vic.blackall

      vic.blackall Well-Known Member

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      What goes into the centre of the large gear? If there is a central shaft fixed to the large gear could you not connect the potentiometer via a small flexible coupling to one end of that shaft. Or drive the pot. from a pair of small timing pulleys, one on the output of the gear, the other mounted on a separate spindle/bearing arrangement which is then connected via a small flexible coupling to the potentiometer.
       
    4. adamru

      adamru Member

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      I am not sure the potentiometer is your best bet, but since you asked here is my analysis:
      Since you cannot place the potentiometer in the hollow center of the large gear you must have a 1:1 transmission to it. The easiest wat would be a timimg belt or chain between it and the potentiometer. However, since the diameter of the large gear and shaft is big a 1:1 transmission rquires a large wheel on the shaft of the potentiometer (and extra bearings to support it). Obviously this can be done only piggyback outside outside the box as was already suggested. However, if you insist on putting it inside the box ther might be a way by meshing with one of the smaller gear inside and making your own parallel geartrain of exactly the same total ratio to the potentiometer. This parallel geartrain may be relatively small usinf fine gears as it bears no load, and thus, with some luck, you may be able to place it inside.
      I must add one reservation though: I am not sure that the potentiometer is your best way systemwise. you did not give much information about the rest of the system, but there are several other ways which may be bette or cheaper if you get rid of the absolute posion analog potentiometer and go digital and incremental.
       
    5. Mastino

      Mastino New Member

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      Thank you very much for your reply! I have chosen this:
      Red is potentiometer.
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    6. vic.blackall

      vic.blackall Well-Known Member

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      Don't forget the flexible coupling.
       
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