Variable discharge and energy recovery is produced by an adjustable spool in fluid communication with the outlet chamber for adjustably providing pressurized fluid from the outlet chamber to selected portions of the demeshing area of the intermeshing teeth to vary the discharge flow of the pump and the amount of energy recovery. This results in maintaining a positive pressure in selected portions of the demeshing area as well as equalizing the pressure in the selected areas to the pressure in the outlet chamber. The adjustable spool also controls the connection between the inlet chamber and the demeshing area to vary the energy recovery.