The complaint arrives the same way in every plant: the cylinder was fast on the bench, and now — under real load — it crawls, drifts or creeps on the way down. The instinct is to blame the pump or the seals, but the honest diagnosis starts elsewhere: gravity is now a power source working against your metering, and the circuit was never asked to handle it. Load control — counterbalance valves, pilot-operated check valves and pressure-compensated flow — is the discipline that fixes it.
What the load does to a simple circuit
On a vertical or over-center load, the falling mass pushes oil out of the rod side faster than the metering valve intends — the cylinder outruns its supply, pressure collapses, and the valve's control authority evaporates. The motion becomes a series of lurches: stick as the valve re-establishes control, slip as the load takes over. It looks like stickiness; it is actually the circuit losing an argument with gravity.
The counterbalance: the load's own throttle
A counterbalance valve installed at the cylinder port holds the load back until pilot pressure signals it to open — the load cannot outrun the valve because the valve opens exactly as fast as the pump's downstream pressure allows. It also catches the load on hose failure, which is why suspended-load safety and smooth metering come in the same cartridge. Setting matters: the relief setting rides above the load-induced pressure with margin, and a wrong setting recreates the lurch it was bought to cure.
Pressure compensation: the speed that ignores load
Where the speed must be constant as load varies — feeding, pressing, lifting at a rate — pressure-compensated flow control holds the metered flow against pressure changes, so the cylinder's speed stops being a function of what it is carrying. Combined with a counterbalance for the over-center case, the circuit finally behaves like the drawing promised.
The hardware lives in the plant's hydraulic cylinder and valve ecosystem — the fix is usually one cartridge and a corrected setting, not a new pump.
Could it be the seals after all?
Yes — but the symptom profile differs: seal leakage shows as drift with the pump stopped and creep toward full extension, while missing load control shows as lurching and speed collapse under motion. Diagnose by the motion's character before ordering cylinders.
Why does my counterbalance valve make noise?
Chattering means the setting sits too close to the load pressure or the pilot ratio mismatches the circuit — the valve is hunting between open and closed. Reset with the manufacturer's margin or re-spec the pilot ratio; noise is the valve asking for a correct setting.
