Pressure Compensated Flow Control
A mechanism that keeps the pressure differential across the valve orifice constant so that the same command gives the same flow rate even when the load changes. In an uncompensated throttle the flow varies with the square root of the pressure differential; in a compensated section the lever angle corresponds directly to speed.
The flow passing through a throttling orifice depends on the cross section of the orifice and on the pressure differential across it. When the load lightens the differential grows and the motion speeds up at the same lever angle; when it gets heavier it slows down. The pressure compensator is a small spool placed before or after the throttling orifice, and it continuously adjusts itself so as to hold that differential typically at around 7-15 bar.
- From the operator's side: whether the bucket is full or empty, the same lever angle gives the same speed.
- From the multi-motion side: when two axes are operated at once the lighter one does not grab all the oil, and both motions proceed together.
- The compensator is the basic building block of load sensing circuits; the pump also adjusts its flow with the same signal.
That is why switching to wireless proportional remote control on a compensated machine gives a much more consistent feel; on an uncompensated open center machine the operator has to keep correcting the lever angle as the load changes. Knowing which type the vehicle is before installing a kit is important for managing expectations.
Where this term is used: The Importance of Hydraulic Control: Why Should It Be Commanded by an Electronic Signal?