Sounds like all answers are in agreement, but the easiest way to explain where the equations come from is to Sum Forces and Moments about a point. The following is copied from software output: Point A is crank, point B is pin joint, point C is piston. ∑M = 0 => −17.160 Ã— RB3[Y] − 5.436 Ã— RB3[X] = −M1 ∑F[X] = 0 => RA3[X] + RB3[X] + R38Fp3[X] = 0 ∑F[Y] = 0 => RA3[Y] + RB3[Y] + R38Fp3[Y] = 0 ∑F[X] = 0 => −RA3[X] = 0 ∑F[Y] = 0 => −RA3[Y] = 0 ∑F[X] = 0 => −RB3[X] − RB5[X] = 0 ∑F[Y] = 0 => −RB3[Y] − RB5[Y] = 0 Resuts RA3[X] = 0.000 N RA3[Y] = 0.000 N RB3[X] = 3939.999 N RB3[Y] = 267.077 N RB5[X] = −3939.999 N RB5[Y] = −267.077 N And of course, Shear and Bending Length CB =3949.04N compression Length BA = 1444.44N shear & 26000Nmm (Note the slight variation in answer is because I havent much time and have some rounding errors on inputs. But the answer shows that the preceding post values are certainly correct) Hope you found that interesting.