Abstract: The invention relates to a method of producing concave, self-contained bearing surfaces, which are at least part of spherical indentations which extend beyond the sphere equator, by means of machining involving the removal of material of pre-formed indentations in workpieces by means of a tool having a tool cutting edge orbiting around a tool axis of rotation with an orbit diameter which is equal to the length of a chord extending up to a deepest point of the bearing surface, whereby the cutting movement is made up of the orbital movement of the tool cutting edge and a rotational relative movement between workpiece and tool around a vertical axis through the sphere center, and the feed movement is a movement of the tool relative to the workpiece along the tool axis of rotation which is obliquely set at the same angle of inclination relative to the vertical axis as is the chord set to the sphere equator.

Abstract: The invention relates to a control and regulating device for a hydrostatic transmission which comprises a reversible hydraulic pump that can be driven by a driving motor, at least one hydraulic motor that is connected via two working lines to the hydraulic pump, and an adjusting device that can be acted on by an adjusting pressure for adjusting the volume and direction of displacement of the hydraulic pump, together with a displacement-direction control valve for controlling and regulating the action of the adjusting pressure on the adjusting device, can be actuated as desired both by a control signal that is proportional to the speed of rotation of the driving motor and predetermines the direction of displacement of the hydraulic pump and by a working pressure signal that is proportional to the working pressure in the working line then carrying the high pressure.

Abstract: The invention relates to a braking valve arrangement for a hydrostatic drive operated in open circuit, in particular for vehicle drives, wherein a hydraulic pressure medium is supplied to the hydraulic motor from the hydraulic pump via a reversing directional control valve as desired through one of two branches each containing a pressure limiting valve and a braking control valve, and the pressure medium is discharged to the tank through the respective other of the two branches. The braking control valve controls the flow of hydraulic medium through the respective branch depending on the pressure in the respective other branch and has parallel with it a non-return valve opening into the hydraulic motor.

Abstract: The invention relates to an axial piston machine of the swashplate type in which the drive shaft passes through the swash plate, the swash plate can be tilted about an effective tilt axis so that its working surface supporting the pistons has a radial component of motion relative to the drive shaft as it is tilted in the direction of which the effective tilt axis is displaced parallel as the swashplate is tilted. In order to adjust the swashplate to a larger tilt angle, according to the invention the effective tilt axis is adjusted radially in a direction opposite to the direction of the radial component of motion (R) of the swashplate working surface.

Abstract: In a piston for piston machines comprising a hollow body, open at least at its free end, having an axial cavity in which there is a filler piece at least partly filling the latter and consisting of a material of lower specific gravity than the material of the piston, said filler piece being secured in the cavity and being held axially in the cavity by a locking element arranged at the free end of the hollow body and a spring arranged between the locking element and the filler piece, the filler piece is inserted axially and the axial securing and locking is effected solely by the spring, which is pretensioned by the locking element to such an extent that it acts against the filler piece with a spring force greater than the maximum inertial forces of the filler piece acting against the spring to be expected when in operation.

Abstract: A control device for a hydrostatic drive for at least two actuators having a variable displacement pump whose adjusting device can be acted on as a function of the displacement and/or of the delivery pressure, wherein a control valve is associated with each actuator in its hydraulic supply line and the delivery flow for each actuator is determined by means of a pressure compensator as a function of the valve preset at the control valve, is simplified while ensuring accurate control. This is achieved by having the adjusting device always set the pump at a displacement which is slightly less than the sum of the actual instantaneous volume flows required by the actuators.

Abstract: An axial piston machine whose pistons are formed as stepped pistons and which bound a first cylinder space and a second cylinder space, wherein the pistons are driven on the driving side via an axially displaceable driving surface on which they slide in a sliding bearing with a pressure pocket which is connected to the first cylinder space by a passage, is arranged so that the loading of the sliding bearings is reduced depending on the operating condition of the axial piston machine. This is achieved by connecting the second cylinder space to a second pressure pocket on one of the two sliding surfaces by a second passage separate from the first passage.

Abstract: With the object of improving the flushing arrangement in an axial piston machine for use in a closed-circuit hydrostatic drive, having a control member (18) that controls the working cycle of the axial piston machine (1) and having a circuit flushing arrangement (31) that includes a flushing valve (33) that is arranged in the control member (18), can be acted on by high pressure and connects the low pressure line (37 or 38) with a return line (44), the valve body of the flushing valve (33) comprises a cylindrical sleeve valve (34) displaceably mounted in a guide bore (35) directly between the high pressure duct (38) and the low pressure duct (37) in the control member (18), the guide bore being connected with the free space (23) of the housing (2) of the axial piston machine in the region of the sleeve valve (34) by a connecting duct (44).

Abstract: An axial piston machine of the skew axis type with at least two independent working streams is described. In this at least two groups of working pistons are arranged in cylinder bores, each on a circle, whereby each group of working pistons delivers an independent working stream or provides a working stream with medium. Such an axial piston machine is constructed as a machine in which the delivery volume is continuously adjustable, and in which the angle of inclination of the cylinder drum can be changed by means of an adjusting mechanism. The entrainment of the cylinder drum only takes place through one of the groups of working pistons.

Abstract: The invention is concerned with an axial piston machine, preferably an axial piston pump of the inclined disc or skew axis type, with a cylinder (9) which rotates about an axis of rotation and in which, on a pitch circle, several pistons (8) are movably guided in piston bores (11) extending substantially along the axis of rotation (3), by means of an inclined or driving disc, or the like, the piston bores (11) opening at the face of the cylinder (9) which is remote from the inclined or driving disc (5), the face resting against a control surface (13) in which there are arranged control openings (14), positioned on the pitch circle of the pistons (8) which, in set positions of rotation of the cylinder (9) are covered by the openings of the piston bores (11), loading cylinders (24) being distributed over the circumference and acting upon the cylinder (9) against the control surface (13), and of which loading cylinders the working spaces are connected, by means of connecting channels (27), each with a respective

Abstract: The invention relates to a swash plate axial piston pump having several pistons, the piston heads of which are held in contact with the swash plate by means of a retraction plate, and having a central pressure-regulating valve which is forced against a valve spring by the pressure in the pressure chamber. The object is to provide a way of fixing the retraction plate on the swash plate which is simple and cheap to construct and install.This is achieved by arranging and fixing the valve spring between the valve body and the retraction plate.

Abstract: The invention relates to a pressure averager for providing an averaged working pressure from the operating pressures of at least two sources of pressure medium, there being provided to average the operating pressures a differential piston of which the number of step faces which face the same direction and which are of equal size corresponds to the number of operating pressures to be averaged, of which the oppositely directed working face is equal to the sum of the step faces, and which is displaceably guided in a correspondingly stepped housing which is provided with supply lines for the operating pressures, and its object is to develop the pressure averager in such a way that an additional pressure relief valve is not required for its function within a hydraulic installation.

Abstract: An axial piston machine has a central bore connected via a connecting duct with the pressure carrying duct of a mirror member. The central bore together with the central pivot acts as a pressure cylinder which exerts a central bearing pressure on the cylinder drum and the mirror member and acts against lifting forces which threaten to lift the mirror member off its slideway. With this additional force it is possible to enlarge the orifices or slots on the rear side of the mirror member so that the area of tilt of the cylinder drum with the mirror member is enlarged. The additional central bearing force applied by the present invention is supported on the drive flange via the central pivot and urges the mirror member against the slideway so as to ensure at all times a secure engagement of the mirror member even when the pressure sides change, that is, a changing direction of tilt of the cylinder drum in a reversing pump.

Abstract: An axial piston machine of the swashplate type has a movable valve plate at the piston end of the cylinder block, and displacement of the valve plate by a stroke control mechanism changes the tilt of the block. The valve plate has a front face subjected to the hydraulic end thrust of the cylinder block and a back face shaped conformably to and engaged with a cylindrical slideway in the machine body. The valve plate is guided against displacement in the direction of the axis of tilt by side surfaces of the machine body. At least one of the front and back faces is spherically arched to cause the hydraulic end thrust to urge the valve plate in a direction to keep one of its sides in continuous contact with a cooperating side face in the machine body. This prevents jamming and wedging of the valve plate in the slideway when the tilt of the cylinder block is adjusted, regardless of the existing load.

Abstract: In a rotary machine a piston member articulated to a rotary drive member reciprocates in a piston-reciprocation chamber in a piston block mounted for rotation obliquely to the drive member. The piston member comprises a first length, whose cross-section decreases with increasing distance in opposite directions from a plane of maximum cross-section corresponding to the chamber cross-section, and an adjacent length, whose cross-section decreases with increasing distance from the first length, engaging in the chamber for torque transmission between the drive member and the block via the piston member.