Valve Gain
This is the change in flow produced by a unit change in signal; it is the slope of the flow-signal curve. A high gain valve responds to a small lever movement with a large speed change and feels harsh; low gain produces smooth control but with a limited top speed.
Gain is expressed as liters per minute per percent of signal. Of two valves with the same nominal flow, one can feel far more aggressive in the field because its deadband is narrow and its curve is steep. That is why nominal flow alone is not enough information when selecting a valve.
- If gain is high, fine placement becomes difficult; the operator transmits even a small shake of the lever to the load.
- If gain is low, motion is easy to control but idle travel takes longer and cycle time increases.
- On the controller side, limiting maximum current or making the curve parabolic is the most practical way to lower effective gain.
In closed loop position control, gain takes on a separate meaning: if controller gain is raised too far, the system starts to oscillate around the target. This is one of the most common causes of the behavior described in the field as "the lever is shaking," and the fix is to reduce gain or lengthen the ramp time.
Where this term is used: The Importance of Hydraulic Control: Why Should It Be Commanded by an Electronic Signal?