What is a load holding valve?
A load holding valve keeps a hydraulic load securely in place and prevents it from moving in an uncontrolled way if system pressure is lost — for example due to a burst hose, a valve closing, or a pump stopping. Other names for the same function are overcenter valve, counterbalance valve and load holding valve. This valve type is central to any application where an overrunning load, a cylinder or a hydraulic motor must be held safely without the drive system being actively pressurized: cranes, presses, lifts, drilling equipment and rotating drives.
How a counterbalance valve works
A counterbalance valve combines two functions in a single cartridge. A check valve allows free flow from the directional valve (port 2) to the load (port 1) when the load is being driven. In the opposite direction — when the load tries to run away on its own — flow from port 1 to port 2 is held back by a direct-acting relief valve. That relief function is pilot-assisted: pilot pressure at port 3 (normally taken from the opposite side of the cylinder or motor) lowers the effective setting by a ratio determined by the pilot area. As long as the directional valve is in neutral, the relief function holds the load still; as soon as the directional valve opens for lowering or rotation, pilot pressure follows along and the valve opens smoothly in step with the load.
A few practical reference points: set the counterbalance valve to at least 1.3 times the maximum load-induced pressure, expect the fully clockwise (minimum) setting to be below 14 bar (200 psi), and note that reseating occurs at a minimum of 85% of the set pressure in the standard configuration. Back pressure at port 2 raises the effective setting further — by a factor of (1 + pilot ratio) times the back pressure — which is worth accounting for in circuits with series-connected functions.
Counterbalance valve or pilot-operated check valve?
Sun Hydraulics also makes a simpler alternative: the pilot-operated check valve (POCV), without a relief function or an adjustment screw. It opens outright once pilot pressure exceeds a threshold, without metering or throttling the load on the way. The choice between the two is rarely a close call:
- Counterbalance valve is the default choice in most cases — overrunning loads, crane lifts, presses and hydraulic motors, where the load can vary or instability must be actively prevented.
- Pilot-operated check valve suits simple vertical loads with no risk of instability, or cases where the lowest possible pressure drop is critical and the load is always predictable.
A practical benefit: in most frame sizes, 3-port counterbalance, load holding and pilot-operated check valve cartridges are physically interchangeable — same flow path, same cavity — which makes it easy to upgrade an existing design without new manifold machining.
Advanced series for varying load and flow
Standard counterbalance valves work well with a fairly constant load, but become inefficient — or even unstable — when the load or flow varies significantly, for example in hydraulic motors or rotating drives. Sun Hydraulics has three specialty series for that type of application:
- LoadReactive — the setting automatically tracks the load pressure, giving a dramatically lower pressure drop at light load. Suits hydraulic motors, rotating loads and a wide flow/load range.
- LoadMatch — combines load reaction with smooth modulation. Suits crane lifts and presses where both stability and energy efficiency matter.
- LoadAdaptive — adapts dynamically to both load and flow, for applications with an extremely wide operating range.
A rule-of-thumb signal to listen for: if the application has a wide flow range (for example 50–500 lpm), a varying load pressure, or feels jerky and inefficient with a standard valve, it’s time to look at one of the three.
What to consider when selecting
- Setting margin — plan for at least 1.3 times the maximum load-induced pressure already at the design stage.
- Draining — the standard version does not have a sealed pilot section and leaks up to roughly 45 ml/min at 70 bar between port 2 and 3 — account for that in master-slave circuits and during leakage testing.
- Environment and materials — corrosion-resistant versions are available with suffix /AP (stainless) or /LH (zinc-nickel plated) for outdoor and marine applications; EPDM seals are required with phosphate ester fluids.
- Varying load/flow — go straight to LoadReactive, LoadMatch or LoadAdaptive instead of trying to compensate with a standard valve.
Not sure which counterbalance valve suits your application? All our load holding valves are described with full technical data on their respective product pages — see for example the CBCA family. And feel free to get in touch, or ask Pascal right here on the site.
