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。

　　Check valves or as a one-way valve. For the hydraulic system to prevent reverse flow of oil flow.

　　A straight-through one-way valves and rectangular Type two. Straight-through one-way valves installed in a connecting thread of the pipeline. Rectangular style is a one-way valve connecting thread, flange type connectivity and connecting three forms. Fluid control valves also known as one-way pressure valve closed valves or insurance, with the same one-way valves to prevent reverse flow of oil. However, the need for oil flow in hydraulic circuit reverse flows can use hydraulic control, opening a one-way valve, so that the flow of oil can flow in both directions. Fluid control one-way valve used cone disc, sealed a good performance. oil flow closed in demand, the availability of one-way valves as oil flow park sky Paul pressure. Fluid leakage control one-way valves control the manner of oil and oil-leaking Type II species. No reverse flow of oil exports in the oil flow available within inflow Type; Otherwise required outflow type, the control of oil in order to reduce pressure.