Abstract: Hydraulic system with a hydraulic machine, in particular an axial piston or radial piston unit, with rotating and moving machine components which are arranged in a housing. The housing is connected to a high-pressure and a low-pressure line of a working circuit, which is supplied with pressure fluid by means of a charge pump. The leakage fluid which occurs in the housing collects in a leakage fluid reservoir which is arranged below the rotating and moving hydraulic machine components in the working position of the hydraulic machine and is connected fluidically to the housing. The leakage fluid is pumped out of the leakage fluid reservoir into the low-pressure line of the working circuit by the charge pump.

Abstract: The invention relates to a hydrostatic transmission having two bent axis- or swashplate-type axial piston units which are operated alternately as a pump and as a motor, with the two axial piston units being adjustable together with a pivotable dual yoke or by means of a pivotable dual swashplate. In order to minimize the dead volumes of the two axial piston units, the rotational axes of the two axial piston power units are offset with respect to the pivot axis of the dual yoke or of the swashplate by a magnitude such that, at all pivot angles, the power unit pistons, at dead center, are located in the direct vicinity of the bore end of the cylinder block.

Abstract: A radial piston pump having external loading. The radial piston pump has an inner eccentric which is attached to a rotatable driveshaft, a cylinder block which has positionally fixed cylinder bores aligned radially with respect to the driveshaft, and displacement pistons which are mounted in a longitudinally movable manner in the cylinder bores. The displacement pistons have a piston head with a short casing height, and are mounted with their piston base on the eccentric, in such a way that the piston head, during its longitudinal movement, pivots in a predetermined angle range (??) about the longitudinal central axis of the associated cylinder bore.

Abstract: Hydraulic system with a hydraulic machine, in particular an axial piston or radial piston unit, with rotating and moving machine components which are arranged in a housing. The housing is connected to a high-pressure and a low-pressure line of a working circuit, which is supplied with pressure fluid by means of a charge pump. The leakage fluid which occurs in the housing collects in a leakage fluid reservoir which is arranged below the rotating and moving hydraulic machine components in the working position of the hydraulic machine and is connected fluidically to the housing. The leakage fluid is pumped out of the leakage fluid reservoir into the low-pressure line of the working circuit by the charge pump.

Abstract: A power split transmission concept for two or three or four modes is provided with two variable hydrostatic units, an engine mechanically connected to the row 1 sun of a planetary gear set with at least two planetary rows, the second row of the planetary rows being connected to a row 2 sun, whereby both hydrostatic units stay connected with the same planetary element through all modes, one hydrostatic unit being connected to the sun of row 2 and the other hydrostatic unit being connected to a ring gear of planetary row 2.

Abstract: The invention relates to a radial piston pump having external loading. Said radial piston pump has an inner eccentric which is attached to a rotatable driveshaft, a cylinder block which has positionally fixed cylinder bores aligned radially with respect to the driveshaft, and displacement pistons which are mounted in a longitudinally movable manner in the cylinder bores, with the displacement pistons having a piston head with a short casing height, and being mounted with their piston base on the eccentric, in such a way that the piston head, during its longitudinal movement, pivots in a predetermined angle range &r about the longitudinal central axis of the associated cylinder bore.

Abstract: The invention relates to a hydrostatic transmission having two bent axis- or swashplate-type axial piston units which are operated alternately as a pump and as a motor, with the two axial piston units being adjustable together with a pivotable dual yoke or by means of a pivotable dual swashplate. In order to minimize the dead volumes of the two axial piston units, the rotational axes of the two axial piston power units are offset with respect to the pivot axis of the dual yoke or of the swashplate by a magnitude such that, at all pivot angles, the power unit pistons, at dead centre, are located in the direct vicinity of the bore end of the cylinder block.

Abstract: A hydromechanical transmission that has first and second planetaries each having first, second and third elements. The first element of the first planetary is connected to a first hydrostatic unit while the second element of the first planetary is connected to a second hydrostatic unit with the third element of the first planetary connected to an input. A primary clutch is connected between first and third elements of the second planetary while at least one secondary clutch is connected to the second planetary. When the primary and secondary clutches are selectively engaged at least two operating modes having continuous ratios are provided.

Abstract: The invention relates to a hydrostatic mechanical traction gearbox having a continuously variable hydrostatic drive in which the hydrostatic drive has a hydrostatic pump driven by an internal combustion engine and a hydraulic motor driven by the pump, the pump and the hydraulic motor are positively coupled in an adjustable fashion by means of a single common pivoting part in such a way that the pump can be pivoted between a minimum angle and a maximum angle while at the same time the motor pivots synchronously from a maximum pivot angle to a minimum angle. The pump is configured for a single delivery direction of the volume flow. A mechanical range change gearbox is connected downstream, said gearbox having a plurality of gear shifting stages which can be shifted by means of a clutch.

Abstract: The invention relates to a hydraulic module for hydrostatic mechanical gearboxes having two swashplates or oblique axis drive units which are integrated in the hydraulic module. The swashplate drive units are mounted in a common housing with parallel drive shafts and each have a rotating cylinder block with expellers which can move therein and which are supported in a sliding fashion on a double swashplate whose pivot angle is adjustable by means of a servo system. The double swashplate is designed to carry out positively coupled common adjustment of the volume flow of the two drive units and is equipped with bearing faces for the expellers of the respective drive units, said bearing faces having different angles of inclination relative to the respective drive shaft. The oblique axis drive units each have a cylinder block with expellers which can move therein and which are each pivotably mounted on the coaxial shafts.

Abstract: The invention relates to an axial piston machine having an bent axis segment which is adjustable by means of an actuating piston, and a variable unit for the electrically proportional adjustment of the displacement. The variable unit has a control piston for controlling the oil pressure which displaces the actuating piston, an electrically controllable proportional solenoid which acts on the control piston, a feedback spring on the control piston for retracting the instantaneous Bent axis valve segment and a adjustment mechanism for setting the start current. To set the start current, the adjustment mechanism has a setting spring which acts on the armature of the proportional solenoid with an adjustable force.

Abstract: A control device apparatus for a proportionally adjustable hydraulic pump of a closed hydraulic circuit, including an axial piston pump adjustable from a zero position in two pivoting directions, with an electro hydraulic valve configuration for the activation of a piston of the hydraulic pump from both sides and with a feedback device, connected to the piston and whereby the angular pivoting position of the piston can be fed back to the valve configuration as a control signal, the valve configuration having a valve for each pivoting direction of the piston, and the feedback device comprising two mechanical feeler elements, each connected to one of the valves and in sliding engagement with the piston in such a way that the feeler elements are actuated when it leaves the zero position.

Abstract: A control device apparatus for a proportionally adjustable hydraulic pump of a closed hydraulic circuit, including an axial piston pump adjustable from a zero position in two pivoting directions, with an electro hydraulic valve configuration for the activation of a piston of the hydraulic pump from both sides and with a feedback device, connected to the piston and whereby the angular pivoting position of the piston can be fed back to the valve configuration as a control signal, the valve configuration having a valve for each pivoting direction of the piston, and the feedback device comprising two mechanical feeler elements, each connected to one of the valves and in sliding engagement with the piston in such a way that the feeler elements are actuated when it leaves the zero position.

Abstract: The output speed of a hydrostatic unit in a transmission is determined using a pair of variable reluctance sensors, one on a gear driven by the hydrostatic unit output and the other on the carrier of the planetary system. One of the two sensors will always be measuring a relatively high speed from which the hydro output is directly determined or indirectly determined using the current engine speed. Thus the frequency of the speed sensor used to determine the hydrostatic unit output speed is not decreased at slow hydrostatic unit output speeds.

Abstract: A loop flushing arrangement for controlling a closed circuit hydraulic propulsion drive. The variable displacement pump 12 is driven by a combustion engine 11. A flush valve 21 is used to clean and cool the hydraulic fluid in the closed hydraulic circuit. The flush valve is electrically operated and, as a result, permits novel and varied control options. The flush valve is controlled automatically, for example by a digital computer 1 as a function of the vehicle speed, the rotational speed of the combustion engine 11, or the temperature of the hydraulic fluid in the variable displacement pump 12. This results in the flushing procedure only being triggered and carried out if the operating state of the vehicle requires and permits it, i.e. when traveling at high speeds, for example.

Abstract: A description is given of an adjustable hydrostatic axial piston machine whose angle can be varied by means of a servo-piston (9) to which actuating pressure can be applied and which is connected to an electrohydraulic control valve. The control valve has a control piston (15) and a control sleeve (22) which can be moved axially relative to one another. The control piston (15) can be axially adjusted with a stepper motor (10), and the control sleeve (22) is coupled mechanically or hydraulically to an adjusting mechanism (9, 7) for the angle for the purpose of feeding back the angle.

Abstract: A variable displacement bent axis hydraulic unit includes a control mechanism having a control housing with a displacement feedback sleeve and spool connected by a spring. A computer controls a proportional solenoid fluid valve that is in operative fluid engagement with the end of the spool opposite its spring connection with the displacement feedback sleeve. The displacement feedback sleeve is urged by the spring into engagement with a cam member on the yoke of the bent axis unit.

Abstract: A special ball joint for servo piston actuation in a bent axis unit includes an elongated actuator rod having a substantially spherical external surface on a first end and a servo piston on a second end. Also included is a single-piece yoke adapted to carry a cylinder block and rotate about an axis of rotation. A socket having a substantially spherical surface is interposed between the yoke and the spherical surface on the rod such that the actuator rod rotates the yoke with forces residing in at least two planes when hydraulic pressure is applied to the servo piston. Two servo pistons and two such ball joints can be applied to the yoke to obtain rotation of the yoke which is up to greater than plus or minus 45° from a neutral position. The external surface on the first end of the actuator rod and the socket must be mating so as to provide freedom of movement. The socket can be incorporated into the yoke itself. The foregoing servo pistons are received in servo bores of a one-piece control housing.

Abstract: A vehicle having a hydrostatic drive and a hydraulic control apparatus, in which the hydrostatic drive has a variable displacement hydraulic pump and a hydraulic motor in a closed circuit, an internal combustion engine for driving the hydraulic pump and a variable displacement pump, producing a volumetric output flow, of an open circuit, and a retarder valve arranged in the open circuit and intended for the hydraulic absorption of braking energy. The retarder valve has a valve and a pressure-limiting valve, connected thereto, for throttling the volumetric output flow of the variable displacement pump. The variable displacement hydraulic pump, the variable displacement pump and the retarder valve are controlled by a digital electronic unit for the respective driving and working functions.

Abstract: A control device for variable hydraulic machines, and specifically for variable axial piston machines equipped with a servo system that is connected to a swash plate so that the discharge/displacement volume is infinitely variable. The hydraulic machine is equipped with a sensor that detects the piston displacement and is connected with an electronical control unit that controls the swash angle position of the swash plate and is pressure controlling the servo system by an electrohydraulic converter. A method for the infinite controlling of the volume flow of hydraulic machines, by which the servo system is connected to the swash plate of the hydraulic machine, and by which a conduction of a signal from a sensor to the control unit, a pressure controlling of the servo system by an electrohydraulic converter as well as the controlling of the swash angle position of the swash plate by the electronical control unit is realized.