In Hartnell governor, the lengths of ball and sleeve arms of a bell crank lever are 120 mm and 100 mm respectively. The distance of the fulcrum of the bell crank lever from the governor axis is 150 mm. Each governor ball has a mass of 4 kg. The governor runs at a mean speed of 300 rpm with the ball arms vertical and sleeve arms horizontal. For an increase of speed of 4%, the sleeve moves 10 mm upwards. Neglecting friction, determine

(a) minimum equilibrium speed if the total sleeve movement is limited to 20 mm,

(b) spring stiffness,

(c) sensitiveness of governor, and

(d) spring stiffness if the governor is to be isochronous at 300 rpm.