單向閥又稱止回閥或逆止閥。用于液壓系統中防止油流反向流動。單向閥有直通式和直角式兩種。直通式單向閥用螺紋連接安裝在管路上。直角式單向閥有螺紋連接、板式連接和法蘭連接三種形式。液控單向閥也稱閉鎖閥或保壓閥，它與單向閥相同，用以防止油液反向流動。但在液壓回路中需要油流反向流動時又可利用控制油壓，打開單向閥，使油流在兩個方向都可流動。液控單向閥采用錐形閥芯，因此密封性能好。在要求封閉油路時，可用此閥作為油路的單向鎖緊而起保壓作用。液控單向閥控制油的泄漏方式有內泄式和外泄式二種。在油流反向出口無背壓的油路中可用內泄式；否則需用外泄式，以降低控制油壓力。

Checkvalvesorasaone-wayvalve.Forthehydraulicsystemtopreventreverseflowofoilflow.

Astraight-throughone-wayvalvesandrectangularTypetwo.Straight-throughone-wayvalvesinstalledinaconnectingthreadofthepipeline.Rectangularstyleisaone-wayvalveconnectingthread,flangetypeconnectivityandconnectingthreeforms.Fluidcontrolvalvesalsoknownasone-waypressurevalveclosedvalvesorinsurance,withthesameone-wayvalvestopreventreverseflowofoil.However,theneedforoilflowinhydrauliccircuitreverseflowscanusehydrauliccontrol,openingaone-wayvalve,sothattheflowofoilcanflowinbothdirections.Fluidcontrolone-wayvalveusedconedisc,sealedagoodperformance.oilflowclosedindemand,theavailabilityofone-wayvalvesasoilflowparkskyPaulpressure.Fluidleakagecontrolone-wayvalvescontrolthemannerofoilandoil-leakingTypeIIspecies.NoreverseflowofoilexportsintheoilflowavailablewithininflowType;Otherwiserequiredoutflowtype,thecontrolofoilinordertoreducepressure.