Hydromatik Gmbh

Brueninghaus Hydromatik Gmbh

Hydromatic Ltd.

Ludwig Wagenseil

Manfred Lotter

Reinhold Schniederjan

Wolfgang Reistle

Hermann Hoffmeister

Horst Deininger

Walter Merkle

Ewald Wachs

Method of producing an undercut, concave, self-contained bearing surface

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. To enable a load that has been decelerated to a standstill both to be maintained at a standstill and also to be shunted without mechanical braking, even when actuation of the displacement-direction control valve by the control signal is interrupted, the invention provides for switching over the working pressure signal applied to the displacement-direction control valve in the absence of the control signal.

Control and regulating device for a hydrostatic transmission

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. To reduce the outlay in the valve and lines a valve unit is provided in each branch of which the valve body is formed as a closure body of the non-return valve, urged in the closing direction by a spring, as a control piston of the braking control valve and as the housing for the closure element of the pressure limiting valve, wherein the valve body is urged controllably towards the closure position depending on the pressure in the respective other branch, and thus acts as a control piston in cooperation with a valve seat to effect controlled throttling of the flow of pressure medium from the control chamber to the tank.

Braking valve arrangement for a hydrostatic drive

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.

Axial piston machine of the swashplate type with radial motion of tilt

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.

Piston for piston machines

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.

Control device for a hydrostatic drive for at least two actuators

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.

Axial piston machines whose pistons are formed as stepped pistons

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).

Axial piston machine with a device for flushing the circuit

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.

Axial piston machine of the skew axis type with two independent working

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 piston bore (11) and the cylinder (9) being supported radially, directly or indirectly, on a support (18) which is fixed relative to the housing (2) and which is spaced axially from the control surface. It is the purpose of the invention, to so arrange the axial piston machine that a balanced axial and radial guidance of the cylinder (9) is possible with maximum use of the piston performance. For achieving this it is arranged that the piston bores (11) open, without narrowing of cross section, at said face (23); that said face (23) is spherically concave and the control surface (13) is correspondingly spherically convex; that the axial portion (F.sub.SK) of a control surface force (F.sub.S), which acts upon the cylinder (9) in the direction of the inclined or driving disc, or counterbalances a loading force (F.sub.ER) which acts upon the cylinder in the opposite direction; and that the size of the radius (R) of the control surface (13) is such that the intersecting point (s) of the control surface force (F.sub.S) perpendicular to the control surface (13) and of the loading force (F.sub.ER) lies in a plane (A) which extends transversely to the axis of rotation (3) and which is arranged in the region of the support (18) of the cylinder (9).

Axial piston machine, more particularly axial piston pump of the

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.

Swashplate axial piston pump

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. This is achieved in that annular grooves in each case associated with a control edge of the respective step faces are provided in the housing, and in that leading away from the annular grooves there are discharge lines which are connected to a common line for the averaged pressure which is connected in turn to the working face.

Pressure averager

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.

Axial piston machine with a tiltable, revolving cylinder drum

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.

Axial piston machine of the type having a tiltable cylinder block

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.

Growing community of inventors

Vohringen, Germany

Ludwig Wagenseil