A four cylinder engine has the two outer cranks at 120° to each other and their reciprocating masses are each 400kg. The distance between the planes of rotation of adjacent cranks are 400mm, 700mm, 700mm, and 500mm. Find the reciprocating mass and the relative angular position for each of the inner cranks if the engine is to be in complete primary balance. Also find the maximum unbalanced secondary force, if the length of each crank is 350mm, the length of each connecting rod is 1.7m and the engine speed is 500rpm.