A hydrostatic axial piston machine includes a cylinder drum having a substantially hollow cylindrical base body, and liners. The body includes cylinder bores located around a central axis. The liners have an outer diameter press-fitted into the bores such that an outer end face of each liner is positioned in a region of an opening of a respective bore, and such that an inner end face of each liner is positioned deep within the respective bore. An outer half of each liner, starting from the outer end face, includes an axially delimited circumferential recess in an outer casing surface of the liner. The machine is configured to operate with great forces acting between the liners and displacement pistons. The recess in each liner is shaped such that, in an axial section through the liner enclosing an axis of the liner, a depth of the recess increases more than once and decreases more than once.

A hydraulic machine comprising: an outer casing comprising a first front plate and a second front plate, a shaft rotatable about a main axis, a first rotor comprising a first rotor body rotatable with said shaft around said main axis, and a plurality of first pistons with respective spherical ring heads fixed to said first rotor body, a second rotor comprising a second rotor body and a plurality of second pistons with respective spherical ring heads, wherein the second rotor is rotatable about a secondary axis, inclined with respect to said main axis, a plurality of sleeves that are separate and independent from each other, each having a cylinder open at opposite ends and engaged on opposite sides by a first piston and by a second piston.

A cylinder block includes: a plurality of cylinder bores including respective openings formed on a piston insertion end surface of the cylinder block, pistons being inserted in the respective cylinder bores and being configured to reciprocate and slide in the respective cylinder bores when the cylinder block rotates; and a cooling portion, wherein the cooling portion includes a plurality of cooling holes each formed between the adjacent cylinder bores and extending from the piston insertion end surface in an axial direction of the cylinder block.

A hydraulic transaxle includes a transaxle casing including an upper transaxle housing and a lower casing, hydrostatic transmission (HST), and an axle. The HST has a hydraulic pump and a hydraulic motor that are fluidly connected to each other. The hydraulic motor has a motor shaft that is drivingly connected to the axle through a reduction gear train that is disposed between the hydraulic pump and the axle. Reduction gear train has a gear shaft supported by the upper transaxle housing via a ball bearing. At least a part of the upper transaxle housing is formed by a gear top cover made of metal and covering the reduction gear train. Ball bearing is supported by the upper transaxle housing and the gear top cover.

A hydraulic machine is described comprising a first part (1, 4) and a second part (7, 8), wherein the first part (1, 4) and the second part (7. 8) are movable relatively to each other in abutting relation, the first part (1, 4) comprises a pressure chamber (2) having a pressure chamber opening (6) in a contact face (5) contacting a sealing face (9) of the second part (7, 8), the second part (7, 8) comprises a low pressure area (10) connected to a low pressure opening (11) in the sealing face (9) and a high pressure area (12) connected to a high pressure opening (13) in the sealing face (9), wherein during a movement of the first part (1, 4) with respect to the second part (7, 8) in a moving direction (14) the pressure chamber opening (6) comes alternatingly in overlap with the low pressure opening (11) and the high pressure opening (13). Such a machine should be flexible in operation with low risk of damages caused by cavitation. To this end a throttling channel (15) in the second part (7. 8) connects the low pressure area (10) with an area in the sealing face (9) in moving direction in front of the low pressure opening (11).

A pump barrel (70) for use in a hydrostatic pump assembly includes a barrel body (88) defining a plurality of piston bores (84) that receive a plurality of pistons moveable within the bores, and a porting face (74) that defines a plurality of ports (72) in fluid communication with the piston bores and providing fluid flow paths into and out from the barrel body. Each port (72) has a leading edge surface and a trailing edge surface relative to a direction of rotation of the pump barrel, said leading and trailing edge surfaces being oriented in a first direction (along line 6-6) at non-right angles relative to the porting face (74). Each port (72) has an inner edge surface (80) and an outer edge surface (82) relative to a radial direction of the pump barrel, said inner and outer edge surfaces (80,82) being oriented in a second direction (along line 9-9) comprising a tilt angle (90,92) relative to the porting face (74) that is different from the angles in the first direction. A hydrostatic pump assembly incorporating such a pump barrel (70) is also disclosed.

A drive apparatus includes an internal sump and a center section having a pump running surface for mounting a pump cylinder block and at least one motor running surface for mounting at least one motor cylinder block. A brake mechanism includes set of brake rod guides are formed in and extend from the center section adjacent the pump running surface and the one or more motor running surfaces for supporting one or more brake rods. The brake rods may engage the motor cylinder blocks at oblique angle thereto, to provide a braking force. The brake mechanism may include a brake shaft, and a brake arm attached thereto and operatively engaged to the brake rods.

A hydrostatic piston engine comprises a housing with a cylinder drum with cylinder bores mounted rotatably therein. Each of the cylinder bores receives a working piston in a longitudinally displaceable manner, via which a hydrostatic working chamber is delimited by the cylinder bore. The hydrostatic working chamber has an opening on an outer surface of the cylinder drum by which, when the cylinder drum rotates, outlets of a high-pressure chamber and of a low-pressure chamber of the piston engine and a reversing surface arranged between the two outlets in the rotational direction can be passed over in alternating fashion. At least one pressurizing medium channel is provided which, on one hand, opens out in the reversing surface and, on the other, into a pressurizing medium trough of the piston engine.

It includes a plurality of cylinders formed on the cylinder block; a piston slidably inserted into the cylinder; a case accommodating the cylinder block; and a valve plate formed by a core member and a resin layer coating the core member, the valve plate being interposed between the cylinder block and an end cover of the case. The valve plate has a first land portion formed by the resin layer, the first land portion being in sliding contact with the cylinder block; and an outer-side non-contact portion provided closer to an outer side in a radial direction than the first land portion, the outer-side non-contact portion being separated away from the cylinder block. At least a part of the outer-side non-contact portion is an exposed portion where the core member is exposed.

A piston pump/motor includes a cylinder block rotated with a shaft; a piston slidably inserted into a cylinder that is formed on the cylinder block; a shoe rotatably connected to a tip end portion of the piston, the shoe being in sliding contact with the tip end portion; and a swash plate with which the shoe is in sliding contact. The shoe has a piston slide portion in sliding contact with the piston and a swash-plate slide portion in sliding contact with the swash plate; a shoe body portion on which the piston slide portion and the swash-plate slide portion are mounted; and a first lock portion and a second lock portion provided across the shoe body portion, and the piston slide portion and the swash-plate slide portion, respectively, the first lock portion and the second lock portion regulating relative rotation between the shoe body portion, and the piston slide portion and the swash-plate slide portion.