| 摘要 |
PURPOSE:To provide a compact servo-motor by balancing force of a balancing device provided in a movable blade side chamber of a cylinder with blade operating force to prevent high pressurization. CONSTITUTION:As a piston 9 moves vertically, an operating rod 6 moves vertically similarly so that a link mechanism composed of a spider 5 mounted on the operating rod 6 and an arm 3 connected to the spider 5 through a ball joint 4 moves a movable blade 1. Blade operating force and spring force are proportional to the opening of the blade, i.e. stroke of the operating rod. Thus, if the spring force is balanced with the blade operating force, blade angle can be varied only by adding hydraulic pressure to unbalance these forces so that a hydraulic cylinder 8 can be made substantially compact. |
