Leakage oil return apparatus for a hydraulic motor

Abstract

The invention relates to a leakage oil return apparatus for a hydraulic motor. The apparatus is used for returning the oil leaked from the working pressure space of a motor (1) into a motor casing (12) from the casing (12) back to a return line (2) of the motor. Consequently, the return pump (5) driven by a shaft (3) of the hydraulic motor (1) has its suction side (7) connected with said casing (12) and its delivery side (6) conencted by way of non-return valves (4) with pressure and return lines (2) of the motor (1) in such a way that flow communication is established always with the line having a lower pressure. It is preferred that the return pump (5) have its delivery side (6) connected by way of a pressure proportional valve (8) with said casing (12). The pressure proportional valve (8) is adapted to receive its control from the pressure ratio between a casing pressure and a pressure in the delivery side (6) of the return pump (5) in such a way that, as the casing pressure goes down below a given pressure limit or approaches the pressure of 0 bar, the pressure proportional valve (8) switches the return pump's (5) volume flow to free circulation i.e. back to the casing (12).

Dependencies are inferred from the claim text.