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Overhead crane and pulleys

  1. Aug 7, 2011 #1
    The problem bellow is a real problem and I would like to get some ideas in order to overcome it.

    As you can see in the attached doc, we have two winches ( drum 1 and 2 ) on the same shaft of motor M1, two moving pulleys ( 3 and 4 ) and a fixed pulley (5).
    The load is 130 Tons, and we can measure that with a load cell at pulley 5 ( 32,5 Tons) after the lifting of the load.
    But during the time as the load is rising we measure only 30 tons! Note that we have a cable of steel with 30mm diam. and the rising speed is about 1m/min.

    When we lower the load, the load cell measures 36,2 Tons. and as soon it stops we get again 32m5 Tons.

    When the load gets the floor than we read 0 Tons (of course!)

    Can someone explain this? This is a real case and my problem is to adjust the safety relay to 110% of nominal load, which is impossible with this beahviour of the system!!
    Last edited: Aug 7, 2011
  2. jcsd
  3. Aug 7, 2011 #2


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    Doc not attached to OP
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