Abstract: The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor (1). A spherical section (8b) is integrally formed on the swash plate-side end surface of a tilt piston (8), and a groove (10) into which the spherical section (8b) is fitted in a slidable manner is formed in the support surface (7b) (second support surface (7b2)) of the swash plate (7). The groove (10) is a part of the second support surface (7b2) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots (11).

Abstract: The present invention addresses the problem of providing a swash-plate hydraulic motor or a swash-plate hydraulic pump having a structure in which the swash plate can be stably held without mounting a shoe to the swash plate-side end of a tilt control piston. An example of the embodiment of the present invention is a swash-plate hydraulic motor (1). A spherical section (8b) is integrally formed on the swash plate-side end surface of a tilt piston (8), and a groove (10) into which the spherical section (8b) is fitted in a slidable manner is formed in the support surface (7b) (second support surface (7b2)) of the swash plate (7). The groove (10) is a part of the second support surface (7b2) and has a shape having a predetermined width and having a longitudinal direction which is oriented perpendicularly to the direction which connects two pivots (11).

Abstract: A hydraulic motor 100 includes a switching valve 3 which is connected to a pilot passage 54 by which a pressure fluid is introduced into a back pressure chamber 21 of a relief valve 2 and takes a first changeover position 3a where the back pressure chamber 21 is connected to a tank 102 or a second changeover position 3b where the pilot passage 54 is connected to the back pressure chamber 21. By this switching valve 3, the pressure fluid supplied to a hydraulic motor mechanism 1 is introduced into the back pressure chamber 21 via the pilot passage 54 when the hydraulic motor mechanism 1 is in operation, whereas the back pressure chamber 21 is connected to the tank 102 as the pressure in the pilot passage 54 becomes not higher than a predetermined pressure when the hydraulic motor mechanism 1 is being braked.

Abstract: A hydraulic motor 100 includes a switching valve 3 which is connected to a pilot passage 54 by which a pressure fluid is introduced into a back pressure chamber 21 of a relief valve 2 and takes a first changeover position 3a where the back pressure chamber 21 is connected to a tank 102 or a second changeover position 3b where the pilot passage 54 is connected to the back pressure chamber 21. By this switching valve 3, the pressure fluid supplied to a hydraulic motor mechanism 1 is introduced into the back pressure chamber 21 via the pilot passage 54 when the hydraulic motor mechanism 1 is in operation, whereas the back pressure chamber 21 is connected to the tank 102 as the pressure in the pilot passage 54 becomes not higher than a predetermined pressure when the hydraulic motor mechanism 1 is being braked.

Abstract: If a first control valve 71 is arranged so as to change between a flow position A and a throttling position C by a fluid for switching purpose guided through a pilot channel 77, the flow area of a first intermediate channel can be changed in two steps. As a result, the injection-valve opening pressure and time of a first relief valve 48 change between two types of values, whereby the physical shock occurring when a crawler vehicle stops can be switched between two types of shock.