The present invention relates to a mechanism for changing the pitch of a propeller of a turbine engine, the mechanism comprising an electrohydraulic actuator that comprises: an electric machine comprising a rotatable actuator shaft; a pumping assembly comprising two hydraulic axial piston pumps, each comprising: o a barrel housed in a cavity filled with hydraulic fluid; o a set of cylinders formed in the barrel, each cylinder housing a translatable piston and comprising an inlet port and a delivery port; o and an inclined plate, the plate of a first pump comprising a crescent-shaped inlet port for circulating the hydraulic fluid when the plate is rotated in a first direction, and the plate of a second pump comprising a crescent-shaped inlet port for circulating the hydraulic fluid when the plate is rotated in a second direction.

Provided is a design method for a self-compensation structure of a cam-lobe hydraulic motor plate distribution system, which comprises that follow steps: firstly, establishing a force balance equation, a pressure distribution equation and a flow balance equation for each balance chamber, setting a boundary condition, and setting an expected nominal clearance; selecting a fit clearance for simultaneous solutions, and obtaining a set of solutions of areas; taking a maximum value in this set of solutions as the median, and setting a set of area values in the optimization design; further solving changing curves of the nominal clearance and the total leakage of the distribution system with the rotation angle of the cylinder block, and calculating the average value of various curves after the operation is smooth, and designing the self-compensation structure based on selection of the optimal combination of the fit clearance and area.

Provided is a design method for a self-compensation structure of a cam-lobe hydraulic motor plate distribution system, which comprises that follow steps: firstly, establishing a force balance equation, a pressure distribution equation and a flow balance equation for each balance chamber, setting a boundary condition, and setting an expected nominal clearance; selecting a fit clearance for simultaneous solutions, and obtaining a set of solutions of areas; taking a maximum value in this set of solutions as the median, and setting a set of area values in the optimization design; further solving changing curves of the nominal clearance and the total leakage of the distribution system with the rotation angle of the cylinder block, and calculating the average value of various curves after the operation is smooth, and designing the self-compensation structure based on selection of the optimal combination of the fit clearance and area.

The present disclosure relates to a control plate (18) configured to equip a hydraulic machine (e.g. an axial piston machine or a pressure exchanger) for a hydraulic fluid, wherein the control plate (18) includes a body (21) having an arrangement of passage openings (22, 23) for the passage of the hydraulic fluid and a contact face, wherein a whole thickness of the body (21) is formed of a main material, wherein the main material is a first polymer material. The objective of the present disclosure is to provide a control plate (18) having a good lifetime. This objective is solved by a control plate (18), wherein the body (21) includes at least one distinct section which is made of a second polymer material (31), wherein the second polymer material (31) is different from the main material.

The present disclosure relates to a control plate (18) configured to equip a hydraulic machine (e.g. an axial piston machine or a pressure exchanger) for a hydraulic fluid, wherein the control plate (18) includes a body (21) having an arrangement of passage openings (22, 23) for the passage of the hydraulic fluid and a contact face, wherein a whole thickness of the body (21) is formed of a main material, wherein the main material is a first polymer material. The objective of the present disclosure is to provide a control plate (18) having a good lifetime. This objective is solved by a control plate (18), wherein the body (21) includes at least one distinct section which is made of a second polymer material (31), wherein the second polymer material (31) is different from the main material.

A control plate (18) of a hydraulic machine is described, the control plate (18) includes a body (21), an arrangement of openings (22, 23), and a contact face (24). In order to operate a hydraulic machine with a low noise level the body (21) is made of a plastic material. The control plate may be used as port plate or as valve plate.