Abstract: A hydraulic gear machine which is particularly suited for use as a reversible hydraulic gear motor includes a pair of gear elements having externally meshing outer peripheral gear portions and stub shafts which are supported in an internal chamber of a housing on respective sleeve-shaped bearings. Two such bearings are arranged at each axial side of the gear elements, one for the stub shaft of each of the gear elements which extends to this axial side. The housing includes a circumferential wall and two end walls. Sealing elements having the configuration of the numeral three are arranged at the interfaces between the bearings and the end walls. The sealing elements are oppositely oriented with respect to a common plane including the axes of rotation of the gear elements at the respective axial sides.

Abstract: An arrangement for centering an end wall of a housing of a hydraulic gear machine, such as a pump or a motor, with respect to the open end of an internal chamber provided in a housing body forming the circumferential wall of the housing includes a plurality of pins which are received in a press-fitting manner in bores of the end wall and protrude beyond an end face of the end wall which faces and closes the open end of the chamber in the mounting position. The pins may have contact surfaces which are turned to the same diameter as the corresponding inner surface of the housing body which bounds the open end of the chamber, or they may exactly fit into the open end, or overlap slightly with the inner surface in which event some material displacement or deformation takes place during the assembly of the end wall with the housing body.

Abstract: A gear machine, such as a gear pump or gear motor, has a housing in a chamber of which there are journalled two gears which mesh with one another. One of the gears is mounted on a drive shaft the end of which is extended outwardly from the housing. The housing is closed at one side thereof with a cover having a stepped bore for receiving the end portion of the drive shaft. The cover is formed with a circumferential projection concentric with the drive shaft and adapted for centering the cover relative to an external element to be coupled with the gear machine. The stepped bore provided in the cover forms a chamber in which a centering ring with a certain radial play is positioned, which centering ring surrounds the drive shaft. A sealing ring is also positioned in the chamber formed in the stepped bore, which sealing ring sealingly closes the housing. The centering ring provides for reliable aligning of the gear machine to the external element adapted to be coupled with the machine.

Abstract: A positive displacing machine has a housing having an interior chamber provided with an open end, a cover closing the open end of the chamber, movable working members located in the chamber and in operation producing high pressure in the same, sealing means including an annular groove formed in one of the elements around the open end of the chamber and a sealing member received in the groove, and a further annular groove formed in one of the elements radially outwardly of the first-mentioned groove and communicating with a space which is under pressure lower than the pressure in the interior chamber of the housing. The housing may have two open ends closed by two covers, and the above grooves may be provided in both end portions thereof. The grooves may be formed both in the housing, and in the covers. The further grooves may be open at a circumferential surface of the housing.

Abstract: An external gear type hydraulic pump or motor wherein the trunnions of gears in the chamber of the housing are surrounded by annular bearing members. The peripheral surface of each bearing member defines with the adjacent internal surface of the housing an arcuate gap whose width increases in a direction toward the respective end face of the corresponding gear. To this end, portions of or the entire peripheral surfaces of bearing members and/or portions of or the entire internal surfaces of the housing have a conical or spherical shape. The gaps are located in the low-pressure zone and reduce the likelihood of wear upon those end faces of bearing members which are adjacent to the end faces of the gears because the bearing members can tilt in response to increasing load without localized rubbing against the gears. Additional gaps can be provided between the end faces of the gears and the adjacent end faces of the bearing members to further reduce the likelihood of uneven wear upon the bearing members.

Abstract: A hydraulic gear machine which may be utilized as a pump or motor has a housing forming a cavity in which a pair of gears having meshing teeth is mounted for rotation. Sealing elements are interposed between the axial ends of the gears and the bearings mounting the gears for rotation; these sealing elements have first surfaces which face the gears and second surfaces facing the bearings and being formed with recesses which form fluid-pressure spaces. At least one seal member is provided adjacent the respective second surfaces and serves to delimit the respective recess. Each seal member has one sealing face which engages an inner circumferential wall of the housing and another sealing face which engages an outer surface of one of the associated sealing element and bearing, which outer surface extends circumferentially of the axis of rotation of the gears.