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Homework Help: Statics - hydraulic crane

  1. Oct 14, 2014 #1
    1. The problem statement, all variables and given/known data
    Hibbler.ch6.p108.jpg The hydraulic crane is used to lift the 1450-lb load. Determine the force in the hydraulic cylinder AB and the force in links AC and AD when the load is held in the position shown.

    2. Relevant equations

    3. The attempt at a solution
    I don't even know....
  2. jcsd
  3. Oct 14, 2014 #2


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    Work back from the load and draw separate free body diagrams for the individual pieces comprising the crane mechanism. By applying the equations of statics to each piece, you should be able to establish te forces in links AC and AD and in the hyd. cyl. AB.
  4. Oct 14, 2014 #3
    So at joints C and D do I let there be a Cx, Cy and Dx, Dy respectively or do I just keep it as Fwd and Fwc? Either way I can't seem to solve it.


    ΣFy=0=Fwc Sin19.74 - 1450

    Fwc= 4203 lb
    WD = 4041 lb

    Then at joint C

    ∑Fx=0=CDsin30 - CAsin30 - 4041

    CD = 4878
    CA = -3204

    Ah my angle was incorrect, substituted 19.74 with 6.18. Still incorrect.
    Last edited: Oct 14, 2014
  5. Oct 14, 2014 #4
    Take moments about D.
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