Pulley & Winch Reaction Loads

[kaffy]

Good Morning,

I hope everybody is well. I’m currently working on a mast design (green structure) that incorporates two pulleys (black) and one winch (blue) & wire rope (red). Based on my rough analysis, the structural steel frame (green) is expected to experience the following reaction forces:

Ra, Rb, Rc, and Rd at the pulley bearing points
Re at the bolted interface between the winch and the steel structure

Questions:
- Does my FBD makes sense or am I missing something?
- Are there any tools / spreadsheets / programs to solve those problems ?

 

[3DDave]

A traditional free body diagram has each body separate with the applied forces and reactions that apply to that component alone.

What you have there is what one draws prior to creating the free body diagrams for each of the parts.

For example, on the pulley that is attached to the vertical post there is a pull on the edge that has to be reacted by a downward force on the pulley axle, but this creates a couple that needs to be reacted by a moment. This would be made obvious if the pulley was alone with only the rope load applied.

 

[Snickster]

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[Snickster]

I believe if you start with the premise that the tension in the rope is constant at all points at 5000 lbs then you can determine the components of all the reactions in your diagram. Then you can determine the resulting forces and moments on the mast.