Patent ID: 8512018

Claim:
A hydraulic device having an inlet side and an outlet side, the hydraulic device comprising: two meshing cogwheels, each cogwheel having external oblique teeth and being arranged between the inlet side and the outlet side; a bearing support provided on an end side of the two meshing cogwheels; an elongated control groove provided in the bearing support and connected only with the outlet side, the elongated control groove periodically producing a pressure equalizing connection during rotation of the cogwheels; wherein the elongated control groove is longitudinal in shape and has a long side; wherein the long side is substantially perpendicular to a line extending from an axis of rotation of a first cogwheel of the two meshing cogwheels to a center of a longitudinal axis of the elongated control groove; wherein the elongated control groove has a longitudinal length and a width, the length being greater than the width; and wherein the elongated control groove has a length smaller than a chordal thickness of a tooth of the first cogwheel such that the elongated control groove is covered by each tooth of the first cogwheel as the teeth are caused to pass over the elongated control groove when the first cogwheel is caused to rotate.