1. Body and the spool hole gap is too small, after the temperature rise, the spool valve bore into the expansion card. 2. spool geometry and geometric tolerance tolerance, empty spool and law do not coincide with the assembly axis, axial hydraulic stuck phenomenon 3. spool surface burrs. Or because the spool is bruised stuck. Three or more of the following methods may be employed treatment; burr on the plug, the available 100 mesh whetstone to clean up, the valve hole burrs or the gap is too small, you can use the corresponding milling bar plus a small amount of diamond polishing paste No. w40 Grinding removed. The oil pollution, failed to filter out particulate impurities stuck spool. 5. Long-term oil temperature is too high, so that the oil deterioration produce gelatinous material, glued to the surface of the valve body and stuck. 6. The oil viscosity is too high, the valve difficult to move even the cardholder does not move 7. Install precision too bad, uneven fastening screws, do not follow the order, or pipe flange joints become warped edge line 8 of the valve body. Chinese hydraulic valve spring reset too hard, too much need impetus, spring deck or spring break, so that the valve can not reset. [Company Name] Tengzhou Lung Machine Co., Ltd. [sales manager] Mr. Sun [Sales Hotline 0632-5878718] [Business Phone] 15165871095 [Main product] single-column hydraulic press, gantry hydraulic machine, single-arm hydraulic machine, hydraulic machine, four-post three beam hydraulic machine, three beam hydraulic machine, hydraulic machine, [company website] http://www.yeyaji2.com/http://www.yeyaji3.com/ http://www.xc-yyj.com/ http: // www.shukongxichuang5.com/http://www.yxyeyaji.com/ http://www.hndyeyaji.com/ [Address] Tengzhou Zone Industrial Park in Southern District