A vertical single cylinder is shown in Figure. The lower piston is connected to the centre crank. The stroke is 80mm for the lower piston. The upper piston operates the two outer cranks which are at 1800 to the centre crank. The reciprocating parts for the lower piston weigh 10 kg. The reciprocating parts for the upper piston weigh 20 kg.
Find the stroke of the upper piston when the primary force is balanced.