| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pressure control valve for hydraulic shovel which does not require skilled ability for an operator and which can easily switch work requiring high digging force with an outer signal at the time of executing horizontal levelling work by the hydraulic shovel. SOLUTION: In this pressure control valve of pilot-operated type, a pilot pressure chamber 18 is formed between a main poppet 15 and a pilot poppet 17 and a spring chamber 14 where a pressure adjusting spring 22 is arranged is provided at the rear part of the pilot poppet 17. The spring chamber 24 is communicated with a low pressure part 13 through a drain path. When the pressure of a high pressure part 12 is raised to be not less than set pressure, the pilot poppet 17 is opened and the pilot pressure chamber 18 is communicated with the low pressure part 13. At the same time, the main poppet 15 is opened and the high pressure part 12 and the low pressure part 13 are communicated with each other. A check valve 27 is arranged in the drain path of the spring room 24 and the check valve 27 is connected/interrupted by an outer signal 38 through a piston 34. Thus, the opening/closing of the main poppet 15 can be switched.</p> |
