The firing order of a cylinder vertical four stroke in line engine is 1-4-2-6-3-5. The piston stroke is 80 mm and the length of each connecting rod is 180 mm, the pitch distances between the cylinder centre lines are 80 mm, 80 mm, 120 mm, 80 mm, and 80 mm respectively, the reciprocating masses per cylinder is 1.1 kg and the engine speed is 2400 rpm. Determine the out of balance primary and secondary forces and couples on the engine taking a plane midway between the cylinder 3 and 4 as a reference plane.