| 摘要 |
<p>The valve is used as a safety arrangement where e.g. cranes are operated hydraulically. The valve consists of a housing (1) in which a valve cylinder (9) is mounted. The valve cylinder is locked in position in the housing by means of a ball (13) which fits in an indent in the housing. The ball prevents the valve cylinder being moved by a spring. The ball is locked in position by a piston (20) which is kept inside the hollow valve cylinder by the pressure of hydraulic fluid. The piston acts against the force of a spring. When the pressure of the fluid in the valve chamber drops, the piston is pushed out of the valve by the spring. The ball is then free to drop out of the indentation, and the valve cylinder is pushed into the closed position by the spring.</p> |
