Rod $AB$ was fixed on a wall at point A and is connected to a structure $BCD$ at $B$ using a smooth pin, with angle ABO$=120.$ The structure BCD is supported by a journal bearing at C and a thrust bearing at D $.$ Rod $AB$ is loaded with force $F_1=40N$ pointing from $E$ to $C.$ The structure $BCD$ is loaded with $F_2=60N$ in y$-$z plane with elevation angle $=30,$ and a couple $M_O=60N*m$ along the z direction. $AB=2m,BO=CD=0\mathrm{.}8m.E$ is the midpoint of AB and O is the midpoint of $CD.AB$ and BCD are lightweighted.

$(1)$ Draw the free$-$body diagram for the whole system including both the rodAB and structure BCD ;

$(2)$ Draw the free$-$body diagram for the structure AB $.$

$(3)$ Determine a force$-$couple system at point E that is equivalent to the actions $($i$.$e$.,F_1,F_2$ and $M_0).$