Patent ID: 8820067

Claim:
A variable displacement hydraulic machine comprising a rotating cylinder including a first series of axial pistons connected to a first plate axially located on a first side of the cylinder in a transverse plane for which the slope can be controlled or adjusted, to form a first controllable displacement for said machine; the cylinder also including a second series of axial pistons connected to a second plate for which the slope is controllable or adjustable and which is located, with respect to the first plate axially on a second side of the cylinder, to form a second controllable cylinder of this machine; the two series of pistons of each displacement each forming a crown centered on the axis of the cylinder and having a different radius such that one of the series of axial pistons defines an inner crown and the other of the series of axial pistons defines an external crown; the two displacements of this machine each including a same number of pistons; the pistons of the inner crown being angularly offset with respect to the pistons of the external crown, and the two series of pistons being received in respective series of bores, the respective series of bores being offset one with respect to the other in their axial direction by partially overlapping each other; wherein the machine includes for each displacement a hydraulic circuit that includes a low pressure chamber and a high pressure chamber, separated by two angular sections situated at two diametrically opposite locations in contact with an external cylindrical wall of the cylinder; the angular sections forming a dynamic seal between the low pressure and high pressure chambers, with each bore of the pistons including a communication conduit radially arranged toward the outside of the cylinder to communicate with the chambers.