SV/SL Modular Check Valve: Load Holding and Lowering
In lifting circuits, a standard check valve creates a common problem. It holds the load in place when the directional valve is centered. But when the operator wants to lower the load, the same check valve blocks the return path. The load stays up, and there is no controlled way to bring it down.
The problem: holding without trapping
The circuit needs to do two things. It must hold a load securely when the valve is in neutral, and it must allow controlled descent when commanded. A standard check valve handles the first task but not the second. An external bleed valve or a separate circuit may be needed, which adds cost and complexity.
The solution: pilot-operated control
The SV/SL Modular Hydraulic Check Valve adds a pilot port to the check valve. When pilot pressure is applied, an internal piston pushes the poppet off its seat. This opens the reverse flow path, allowing oil to return from the cylinder to the tank. The operator can extend, hold, and retract the cylinder using the same directional valve.
View SV/SL Modular Hydraulic Check Valve Specifications
Key specifications:
Maximum working pressure: 315 bar (31.5 MPa)
Specifications: 10, 20, 30
Flow ratings: 120 L/min (Spec 10), 350 L/min (Spec 20), 300 L/min (Spec 30)
Design number: 40
Mounting: modular, subplate mounting
Why Spec 30 is rated lower than Spec 20
Spec 20 handles up to 350 L/min. Spec 30 handles up to 300 L/min. This is not a misprint. Flow capacity depends on internal passage size and spring characteristics, not just external dimensions. Each specification is built for a particular manifold pattern and flow range. When selecting, match the flow rating to the system pump output.
Where it fits
The valve is used in circuits that need load holding with controlled lowering. Typical applications include lifting equipment, industrial presses, and mobile machinery where an actuator must stay in position without drifting. Because it is modular, it stacks with directional valves and pressure valves in a manifold assembly, reducing external piping and leak points.
About the manufacturer
Shijiazhuang Laiye Import & Export Trading Co., Ltd. is part of Hebei Onederful Hydraulic Technology Co., Ltd., founded in 1988. OEM customization is available with drawings and specifications.
