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Homework Help: MECHANICS: Forklift Problem (Frames and Machines)

  1. Nov 2, 2011 #1
    1. The problem statement, all variables and given/known data
    Assume that the pin joints at A,E, and F, are attached to the rest of the truck body, which is not shown. If a 8-kN weight is concentrated on the fork as shown, find the forces that the pins on member CDE experience. All joints can be modeled as pins.

    3. The attempt at a solution
    My question is only about the FBDs that I have so far. I see that both members AB and DF are two-force members, meaning the forces in them have the same magnitude, same line of action, and opposite direction. So member AB should have two forces, one pointing up and one pointing down. I just don't see how FBC comes into the picture, since it has both X- and Y-components... Any hints would be greatly appreciated.
  2. jcsd
  3. Nov 3, 2011 #2


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    Science Advisor
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    Gold Member

    Nice observation!
    yes, you are quite correct; A_x = B_x = 0.
    Now why do you say that? Member BC__ is not a 2 force member. Newton 3 will give you the direction of FBC. Trust your instincts.
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