Abstract: A hydraulic vane machine has a rotor, in which several vanes are arranged radially movable, and a stator having a stator bore, whose wall is made as a guiding contour on which the vanes bear. It is intended to prolong the life of such a machine, even when the machine is operated with a poorly lubricating hydraulic fluid, such as water. For this purpose at least one vane has a wearing surface on the end bearing on the guiding contour. Further, a channel arrangement is provided between high pressure and low pressure sides of the vane, which channel is blocked as long as the wearing surface has a predetermined thickness, and opened when the wearing surface is thinner than the predetermined thickness.

Abstract: A hydraulic axial piston machine (1) is disclosed, having a cylinder drum (3) with at least one cylinder (4), in which a piston (5) is arranged to move back and forth, which piston bears by way of a slider shoe (7) against a swash plate (8), wherein a pressure plate (9) is provided which holds the slider shoe (7) in contact with the swash plate (8) and is supported against the cylinder drum (3) by way of a ball-and-socket joint (10) comprising a ball-like body (12) and a counterpart (13). In such an arrangement, one would like to avoid weakening the pressure plate by the ball-and-socket joint. To that end, a part of the ball-and-socket joint (10) is provided with a supporting surface (17) which extends substantially parallel to the surface of the pressure plate (9) and by means of which this element (12) lies in face-to-face contact with the pressure plate (9).

Abstract: A control plate (1) of a hydraulic machine having a core (2) is disclosed, which at least on its upper side (O), lying in operation against a cylinder drum, is covered with a layer of friction-reducing plastics material (3). The plastics material (3) is joined to the core (2) by means of a connecting element (8) which, as a result of interlocking engagement with the plastics material (3) and/or the core (2), takes up tensile forces substantially at right angles to the upper side (O).

Abstract: A hydraulic axial piston machine is described, having axially movable pistons, which at one end bear by means of slider shoes against a slanting plate, and having a pressure plate (10) for holding the slider shoes in contact with the slanting plate. Under certain operating conditions the slider shoes have a tendency to tilt and lift away from the slanting plate at one side. To prevent this, the pressure plate (10) acts only on a part lying, in the radial direction of the slanting plate (7), outside a predetermined region (28).

Abstract: A hydraulic piston machine is disclosed, having a cylinder body, which has at least one cylinder, in which a piston is arranged to move back and forth and bears by way of a slide shoe against a control surface, and having a pressure plate which holds the slide shoe in engagement with the control surface. It is desirable to be able to operate such a machine also with a fluid that has no or only poor lubricating properties. To that end, the pressure plate and/or the control surface is provided with a layer of a friction-reducing plastics material at least in one of the regions with which in operation they rub against other parts.

Abstract: A piston/slide shoe arrangement of a hydraulic piston machine is disclosed having a slide shoe in connection with a piston (4), with a friction reducing plastics material there between, wherein the plastics material, forming channel, extend into a through opening in the slide shoe in a direction towards a sliding contact surface of the slide shoe. The sliding contact surface in operation lies against a swash plate. The slide shoe and the plastics material are provided outside the through-opening with at least one connecting element which takes up the shear forces between the slide shoe and the plastics material.

Abstract: A hydraulic axial piston machine is disclosed, having a cylinder drum which is mounted for rotation relative to a housing (1), with a bearing (3) having a slide face (4) being arranged between the circumference of the cylinder drum and the housing (1). It is desired that such a machine shall be capable of operating also with fluids that are not such good lubricants as hydraulic oil. For that purpose the slide face (4) is formed by a friction-reducing plastics material and has at least one recess (5, 6, 7) communicating with at least one end edge of the slide face (4).

Abstract: A hydraulic piston machine is proposed, with a cylinder body (1), which comprises at least one cylinder (2) with a piston (3) movable therein, and a control counter-plate (7) which engages the cylinder body (1) by way of a contact surface (6) and, on relative movement between the cylinder body and the control counter-plate parallel to the contact surface, connects the cylinder in dependence upon its position with inlet and outlet channels (11, 12) respectively, the control counter-plate (7) and/or the cylinder body (1) being provided, at least in the region of the contact surface (6, 9), with a friction-reducing layer (13). A machine of that kind should be inexpensive to manufacture yet should operate reliably even when the hydraulic fluid has no or only slight lubricating properties. For that purpose the friction-reducing layer (13) is in the form of an injection-moulded part.

Abstract: A hydraulic piston machine is disclosed, having a cylinder drum and a control plate, which control plate has at least one high-pressure "kidney" and at least one low-pressure "kidney" and also a contact surface against which the cylinder drum bears in operation, at least the contact surface being provided with a friction-reducing layer. It is desirable for such a machine to have better operational behavior and a longer service life. For that purpose, the contact surface in the region of the low-pressure kidney has a recessed region forming a gap between the cylinder drum and the control plate.

Abstract: A hydraulic axial piston machine is disclosed, with a cylinder drum (2), which has at least one cylinder (3), in which a piston (6) is mounted so as to be axially displaceable, and with a control counter-plate (11 ) which, on rotation of the cylinder drum (2) and the control counter-plate (11 ) relative to one another, connects the cylinder (3) in dependence upon its position with a fluid inlet (14) and a fluid outlet (15). With a machine of that kind, it is desirable to improve balancing out of the forces necessary for effecting a seal between the cylinder drum (3) and the control counter-plate (11). For that purpose, between the cylinder drum (2) and the control counter-plate (11 ) there is arranged a pressure plate (17) which engages the cylinder drum (2) via the intermediary of a spring element (21), the pressure plate (17) having a through-opening (20) associated with the cylinder (3), which through-opening is connected to the cylinder (3) in a fluid-tight manner.

Abstract: A hydraulic pumping device for use in a hydraulic machine having a piston and slider shoe unit made of a combination of plastic and metal material to operate with virtually lubricant free fluid.