When the piston of servomotor 1 is moved downward by the action of fluid delivered to the cylinder, cable 2, running over round pulleys 7, 6 and 9 and attached to the servomotor housing at point a, turns lever 3 about fixed axis A. This lifts stem 4 which has pin d sliding in slot b of lever 3. The conical tip at the lower end of stem 4 opens the hole in valve seat 5, screwed into the body of the valve into which fluid is delivered. When the piston of servomotor 1 moves upward, the valve is closed by the action of weight 8 which can be adjusted to the required position along the axis of lever 3.
$3956$LHP,Va$