Abstract: The invention concerns a hydraulic machine with a set of teeth, having a toothed ring with an inner toothing and a gear wheel with an outer toothing, the gear wheel rotating and orbiting in the toothed ring, the inner toothing and the outer toothing touching each other in contact areas, thus separating pressure chambers, and with a valve arrangement controlling a connection between a connection arrangement having a high pressure connection and a low pressure connection, and the pressure chambers. It is endeavoured to achieve a stable operation, particularly with low speeds. For this purpose, each contact area is provided with an opening, which, at the time when a pressure chamber reaches an extreme value of its volume, produces a short-circuiting with the neighbouring pressure chamber.

Abstract: The invention concerns a hydraulic machine (1) with an externally toothed gear wheel (2) and an internally toothed ring (3), which is made of a sintered material or of a ceramic material. It is endeavored to provide good operation behaviour at low costs. For this purpose, the toothed ring (3) is provided with a sealing element (7) in the area of its outer circumference.

Abstract: A hydraulic machine with an orbiting displacement element connected unrotatably with an output shaft via an intermediary shaft, the intermediary shaft having at least at one end an external toothing, which engages an internal toothing, which permits a swivel motion of the intermediary shaft. The external toothing has teeth with concavely shaped tooth sides having a smaller curvature at the axial ends than in the area of the axial center.