Example of support reaction:

A fixed crane of 1000Kg mass is to lift 2400Kg crates. It is held in place by pin at point A and a rocker at point B. the C.G. is located at G. Determine components of reaction at point  A and B after drawing free body diagram.

Sol.: Since the two reaction (Vertical and Horizontal) at pin support that is, RAH and RAV. And at rocker there will be only one Horizontal reaction that is,R_BH  .

First draw FBD of the Jib crane as shown in the given figure. The whole system is in equilibrium. Take moment about the point A

∑M_A = - R_BV  × 1.5 + 1000 × 2 + 2400 × 6 = 0

R_BH = 10933.3Kg                                      .......ANS

∑H = 0

R_AH  + R_BH = 0

That is,                  R_AH = - R_BH

R_AH = -10933.3Kg                                   .......ANS

∑V = 0

R_AV  - 1000 - 2400 = 0

R_AV = 3400Kg                                            .......ANS