| 摘要 |
A load control system is disclosed for preventing the uncontrolled lowering of a load should a line failure occur in a hydraulic system. The system is designed to be used with a hydraulic cylinder having a movable piston therein which divides the cylinder into a head end and a rod end. Attached to the piston and extending out of the hydraulic cylinder is a piston rod which has a load secured to its free end. The load control system includes a source of pressurized fluid, the flow of which is selectively controlled to the hydraulic cylinder by a control valve. Positioned between the control valve and the head and rod ends of the hydraulic cylinder, respectively, are first and second valves each of which is normally biased towards a closed position by a common pressure. The first and second valves are urged toward an open position by fluid pressure taken between the control valve and the first valve and are movable by this fluid pressure in a proportional manner with the second valve being opened first. The second valve is also physically mounted directly to the hydraulic cylinder such that if a line breakage occurs, the load will still be unable to drop.
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