Variable capacity gear pump with pressure balance for transverse forces

A gear pump having a casing and a first rotating, toothed pump gear and an opposing second pump gear, said first pump gear being supported axially displaceable in the pump casing and engaging an axially displaceable sliding part on at least the one face wall of said first pump gear, said second pump gear being axially stationary in said casing, said sliding part being adapted to overlap the engagement zone occupied by the first pump gear opposite the second pump gear, the part of the surface of said sliding part facing said second pump gear having a contour matching the path of the teeth of said second pump gear, wherein the improvement comprises:

• a pocket-like recess in the pump casing disposed between the first and second gears of the pump on the side diametrically opposite the pressure side of the pump across the axially displaceable first pump gear, said recess hydraulically communicating with the pressure side and disposed in a location in the pump casing which is disposed within the zone of engagement of the pump gears even when said first pump gear is axially displaced.