2017 China New Design Double Action 12v/24vdc Hydraulic Power Pack - Monoblock Valves-GDV25 series – Guorui

GDV25 series mono-block valve is an open center,3 position 4 way valve. Flow from pump passes through inlet port and enters to inlet passage.The inlet passage connects two passage:one is through the load check into the parallel passage to supply flow to metering spool;Another is to neutral passage .When spool is in neutral position,spool metering with parallel passage is blocked.The oil from pump has to pass through neutral passage.When all spools are in neutral position ,parallel passage for each spool is blocked,and neutral passage is wide open.Therefore,oil from pump is directly passing through the neutral passage to return passage to tank.It produces small pressure drop from “P” to “T”.When one of the spools is moved to “1” or “2” position,the spool blocked the neutral passage.The flow from pump has to pass load check to parallel passage,then through valve opening between parallel passage and spool to work port “A” or “B”. For multi-spool mono-block valve, when one of its spools is in “1” or “2” position,its downstream of the neutral passage has no flow. The operator can operate more than one spools at a time, but the speed of the controlled device will be dependent on the magnitude of the load.