A gear wheel (10) for a hydraulic apparatus is rotatable about an axis of rotation (H-H) and comprises a plurality of teeth (11) having a sectional profile (P) and being adapted to mesh with respective teeth of another gear wheel during a rotational motion about the axis of rotation (H-H), wherein at least one tooth (11) is shaped so as to have at least one cutting edge (12) configured to remove material, in particular chips, from a body which is contacted by the cutting edge during the rotation of the gear wheel (10), wherein the cutting edge (12) is defined by at least one groove (14) which is lowered by amount from 0.2% to 5% of the height (H′) of the tooth (11), said the groove (14) decreasing away from the cutting edge (12) along the profile (P).