Overcentre Valves

Safe and Controlled Motion in Hydraulic Systems

Overcentre valves, sometimes referred to as load-holding, motion control valves, are a specialised type of hydraulic valve designed to provide load holding, safety, and smooth control of actuators. They can be described as pilot-assisted relief valves with an integral free-flow check, ensuring controlled movement in one direction while preventing runaway loads in the other.

At Hydraulics Online, we supply overcentre valves from a wide range of global manufacturers – including Argo Hytos, Atlantic Fluid Tech, Eaton Vickers, and many others – with expert advice to help you select the right valve for your application.

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Overcentre valves are typically mounted directly onto the actuator – whether a linear cylinder or a rotary hydraulic motor – to provide the most effective control. If direct mounting isn’t possible, they should be connected to the actuator using rigid piping to maintain stability and safety.

Their key functions include:

Preventing uncontrolled actuator movement – especially in load-lowering applications
Providing load holding capability – keeping cylinders or motors locked in position
Ensuring smooth motion control – avoiding jerky or unstable operation
Protecting against pressure spikes – acting as a relief valve under overload conditions

Safety assurance – prevents runaway loads and uncontrolled actuator descent
Smooth operation – ensures controlled lowering and precise actuator movement
Load holding capability – locks actuators securely in position when required
Energy efficiency – reduces wasted energy by controlling flow effectively
Versatile mounting options – direct actuator installation or rigid piping connections

Overcentre valves are widely used in:

Mobile machinery (construction, agriculture, forestry)
Cranes, lifts, and access platforms
Industrial automation and material handling systems
Marine and offshore hydraulic equipment
Energy and utility installations

They are particularly valuable in systems where safety and controlled motion are critical.

How do overcentre valves differ from standard relief valves? Overcentre valves combine relief functionality with motion control, preventing uncontrolled actuator movement while allowing free flow in the opposite direction.

Can overcentre valves be used with hydraulic motors? Yes – they are suitable for both linear actuators (cylinders) and rotary actuators (motors).

Do overcentre valves improve safety in lifting applications? Absolutely, they prevent loads from dropping uncontrollably, making them essential in lifting and lowering systems.