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 with a toothed set comprising a toothed ring with an inner toothing, whose circumferential surface extends in parallel with its axis, and a gear wheel (3) with an outer toothing, whose circumferential surface (24) extends in parallel with its axis, at least one tooth flank having an edge as an axial end of a section, which is located between the circumferential surface and a surface directed radially inwards. It is endeavored to reduce the wear. For this purpose it is ensured that in the radial direction an edge (22, 23) ends so as to be offset inwards in relation to the circumferential surface (24).

Abstract: The invention concerns a method and a hydromachine with a commutation device and with expanding and contracting pressure chambers passed by fluid and formed by displacement arrangements. With the method and the hydromachine, it is endeavoured to control a displacement in the hydromachine to keep pressure fluctuations small. For this purpose, the hydromachine has a group of devices, comprising a commutation device and at least two displacement devices, at least two of the devices being adjusted in relation to each other.

Abstract: A hydraulic motor of the disc valve type has a disc valve with a plurality of commutation slots that can sequentially register with ports in a port plate as the disc valve is rotated with respect to the port plate. The commutation slots have a geometrical configuration that is complimentary in shape to a portion of the geometric configuration of the ports in the port plate to reduce the resistance to fluid flow through the ports and the slots when the complimentary shapes move into or from superimposed registering positions.

Abstract: A gerotor motor has a housing located adjacent a port plate. The housing has two fluid chambers on opposite sides of a disc valve. The disc valve is in sealing surface engagement with the port plate to prevent fluid from moving between the fluid chambers. The valve assembly has forward and rearward sides and has substantially equal volumes of material removed therefrom so as to balance the port plate against any torsional forces imposed on the valve assembly which might otherwise deflect the valve assembly to interfere with its sealing relationship with the port plate.