Hydraulic machine pressure valve main valve failure cause analysis 1, the main valve orifice plugged (the assembly of the main spool is not cleaned, oil too dirty) Solution: Clean the orifice so that flow; filter or replace oil. 2, the main valve stuck in the open position (such as low precision parts, poor assembly quality, oil too dirty) Workaround: open repair and re-assembly, valve cover fastening screws tightening force should be uniform, or replace the oil filter . 3, the main valve return spring is broken or bent, so that the main valve can not be reset Solution: Replace the spring. [Company Name] Tengzhou Lung Machine Co., Ltd. [sales manager] Mr. Sun [Sales Hotline 0632-5878718] [Business Phone] 15165871095 [Main product] small hydraulic machine four-post hydraulic machine hydraulic machine for small gantry hydraulic machine, hydraulic machine, single-column hydraulic machine universal hydraulic four-post three beam hydraulic machine press four-post three beam hydraulic machine hydraulic machine [company website] http://www.youyaji1.com http://www.yeyaji1.com/ http://www.yyj-yx.com/ http : //www.hengnuoda.com/ http://www.yaliji1.com/ [Address] Tengzhou Zone Industrial Park in Southern District