Mannesmann Rexroth Corporation

G. L. Rexroth Gmbh

Mannesmann Rexroth Ag

Heinz Schulte

Norbert Mucheyer

Wolfgang Kauss

Reiner Bartholomaus

Kurt Wittich

Herbert Lembke

Winfried Rub

Karl-Heinz Bernhardt

Hans-Dieter Kokus

Wolfgang Eberhard

Hydraulic device for controlling a hydraulic-fluid flow

A fluid operated positioning apparatus includes a multi-position valve operated in response to differential pressure in a fluid control circuit. The control circuit includes two adjustable throttles in series, the junction between the throttles being connected to a control device at one end of the valve. Particular relationships for the throttles are disclosed. Other embodiments include additional throttles for improved control with low pressures.

Apparatus for controlling an adjustable member

A device for controlling an adjustable arm 1 has an operating circuit 10 including a movable valve 3 with two control mechanisms 11, 12 bidirectionally actuated by pressure. A control circuit to activate the movable valve is connected to a pressure source 19, to the two control mechanism 11, 12, and to an adjustable throttle 22 attached to one of the two control mechanism 12. The control circuit also includes an adjustable throttle 24, series connected adjustable throttles 27, 28 attached to the other control mechanism 11 and a fifth adjustable throttle 57. The fifth throttle is used to create an additional actual value input. An adjustable control valve 53 employs the desired and actual value inputs supplied by the adjustable throttles in various ways by interconnecting the throttles with the control devices and a pressure ratio valve 45 so that the system responds to applied force, position or both.

Apparatus for controlling an adjustable arm

A pressure-relief valve has a housing forming a chamber extending along an axis and a valve seat centered on the axis and subdividing the chamber into an outer high-pressure compartment and an inner low-pressure compartment. The seat defines generally the only fluid-communication path between the compartments. A pump and a load can be connected to the high-pressure compartment and a sump to the low-pressure compartment. A valve body is formed with a central radially outwardly open main groove, an outer face exposed in the high-pressure compartment, an inner face exposed in the low-pressure compartment, a radially outwardly open control groove offset axially inward from the main groove toward the inner face, and a diametrally throughgoing control bore at the main and control grooves. The body is axially displaceable through the seat between a closed position substantially blocking the seat with the main groove and control bore axially offset therefrom and an open position axially offset toward the low-pressure compartment from the closed position and with the main groove and control bore at the seat for flow through the main groove and seat between the compartments, and through an intermediate position between the open and closed positions and with the control bore at the seat for flow through the control bore and control groove between the compartments. A spring urges the valve body axially outward toward the high-pressure compartment into the closed position.

Hydraulic pressure-relief valve

An apparatus for positioning an adjustable member as a function of a command signal and a control condition, especially for the positioning of a hoisting mechanism on a tractor or the like, comprises an operating circuit and a control circuit. The operating circuit has a bidirectional positionable valve with a valve side and first and second control devices for regulating flow of pressure medium from a supply tank to the adjustable member. The control circuit connects a control pressure medium source to the control devices at first and second junctions and includes adjustable throttles and a flow-regulating valve. A first adjustable throttle is connected between the supply tank and the first junction. The second adjustable throttle is connected between the control pressure medium source and the first junction and in series with the first adjustable throttle. Third and fourth throttles are connection in series with the third throttle being connected between the supply tank and the second junction, and with the fourth adjustable throttle being connected between the control pressure medium source and the second junction. The flow regulating device is connected between the control pressure medium source and the first junction in parallel with the second adjustable throttle such that the flow regulating valve can be located in a remote location from the remaining controls, permitting remote operation of the adjustable member.

Apparatus for positioning an adjusting member

A hydraulically unblockable non-return valve has a control piston (21), the control side of which can be connected with a control pressure medium source (35) and the other side of which can be connected with a supply container (33). In order to create a hydraulically unblockable non-return valve, in which the control side of the control piston does not need to be relieved of pressure, the other side of the control piston is perpetually connected with the supply container. Also provided is a throttle bore (27) which connects the two sides of the control piston with each other.

Hydraulically unblockable non-return valve

A pressure fluid operated limit switch, particularly for a device for controlling an adjusting element in dependence upon a control value and a reference value. The limit switch includes a housing formed with a recess in which a spring-biased valve member is positioned. The valve member normally abuts against a valve seat formed by a shoulder in the switch housing is at times moved away from that seat against the force of the spring in response to a condition of the adjusting element with which the limit switch is mechanically connected. In order to ensure rapid movement of the valve member away from its seat and thus preventing throttling of the pressure fluid when the switch is in its open position the valve member is provided with the actuating element rigidly connected thereto and carrying at its free end an axially slidable sleeve biased by a spring which is clamped between that sleeve and the valve member.

Pressure-fluid operated limit switch

The assembly is used with a support having a flat surface and formed with a bore extending generally parallel to but beneath the surface and with a passage extending from the bore to the surface, with a control element in the bore and pivotal therein about an axis generally parallel to the surface, and with a control rod projecting from the element through the passage beyond the surface. This rod is connected to the element and pivots therewith about the axis through an arc on pivoting of the element in the bore about the axis. The assembly comprises an elastomeric annular cuff having an inner periphery tightly engaging and secured against movement on the rod and an outer periphery engaging and slidable on the surface all around the passage and dimensioned to engage the surface all around the passage in any position of the rod. This cuff is prestressed generally parallel to the rod between its peripheries to press at the outer periphery against the surface. Thus as the rod pivots the periphery slides on the surface while remaining in sealing contact therewith. As a result a dust-tight seal is created which allows the rod to move very freely, either pivoting or rotating.

Seal assembly for pivotal rod

A control-circuit throttle valve assembly coupled to and regulating a hoisting unit correcting element or final control element of a tractor via a mechanical coupling including a throttle housing, a flow restrictor throttling body shiftably mounted in the throttle housing, the throttling body having a guiding edge portion, a control conduit with a circular cross-section communicating with the throttle housing, the control conduit including a pass-through area, and a run-off conduit communicating with the throttle housing, the guiding edge portion at least partially closing off communication between the control circuit and the throttle housing through the pass-through area upon shifting of the throttling body within the throttle housing such that the pass-through area is throttled as a linear function during operation of the hoisting unit.

Control-circuit throttle valve

A suction container for two hydraulic circuits, particularly for a steering circuit and a control circuit has a housing lower portion closed with a cover. A suction tube is inserted into the housing lower portion, which tube is connected to a first consumer line. The container also includes connections which are in communication with a second consumer line and with a fluid supply container. During operation the suction container is under predetermined pressure. A filter device is disposed in the cover before the connection to the second consumer line. A pressure-limiting valve and a reverse valve openable into the container housing are also mounted in the cover.

Pressure container for two hydraulic circuits

A multi-way valve for precisely controlling supplying pressure to a load device, comprising a housing and a control slide slidably mounted in the housing. The housing has annular, internal passages axially spaced along the length of the housing, with first and fifth passages located on opposite sides of second, third and fourth passages in fluid communication with a supply tank, the load device and a fluid pressure source, respectively. The control slide is slidably mounted in the passages and has parts axially spaced along the slide and axially separated by annular grooves, and an internal, longitudinal passages. First and second springs are coupled to opposite ends of the slide and bias the slide to a middle, rest position. First and second control chambers are located in the housing adjacent the slide opposite ends for applying varying pressures to the slide opposite ends. One of the annular grooves on the shaft controls connections of the load device with the supply tank and fluid pressure source and has restricting means for reducing the tendency of the slide to reciprocate.

Multi-way valve

A control circuit throttling valve provided as a controlled dimension receiver in a hydraulic circuit for the control of a final control element, particularly for the control of a lifting unit of a tractor. The valve performs a receiver function under control of a mechanical coupling coupled to a moving part of the final control element which changes the valve throttling section and is adjustable and includes a casing having a control connection and a discharge connection and a movable throttling body provided in the casing in relation to the control connection and the discharge connection such that upon linear or rotational movement of the body it is possible to independently derive an adjusting function and a receiving function.

Control circuit throttling valve

The invention provides a device for regulating the tractive force in the lower linkage system of a tractor lifting gear which serves, for example, to hold a plough. The lower linkages on which the tractive resistance, acting on the plough, is exerted transmit the tractive force to a bending bar, the bending of which is recorded as a measurement of the tractive force. In accordance with the invention the bending bar is rigidly coupled to a bearing frame which is rigidly mounted on the tractor and which absorbs the force acting on the lower linkages while the bending bar is subjected to bending strain. This means that the lower linkages do not exert a force directly on the bending bar, and the bending bar can therefore be supported free from play.

Device for regulating the tractive force in lower linkages of tractor

A hydraulic control arrangement with a feedback device for positioning an implement comprises a positioner including a fluid operated cylinder and piston unit, the piston of which is connected by a plurality of linkage elements to the implement. A first pump delivers through a pressure line fluid under pressure into the cylinder. A two-port three-position valve is interposed in the pressure line movable from a neutral position in which the fluid fed by the first pump is directed to a reservoir, to two operating positions to opposite sides of the neutral position, and in which one of the operating positions fluid fed by the first pump passes into the cylinder and in the other of the operating positions fluid from the cylinder can flow to the reservoir. A pair of pilot chambers are arranged at opposite ends of the valve for moving the latter from the neutral to either of the working positions. A second pump provides fluid under pressure for operating the valve. A first control line leads from the second pump to one of the pilot chambers and a fixed throttle cooperating with an operator adjustable throttle is located in the first control line. The arrangement includes also a feedback device comprising a second control line leading from the second pump to the other pilot chamber and a second fixed throttle cooperating with a second adjustable throttle is located in the second contial line. The flow-through cross-section of the second adjustable nozzle is adjusted by engagement with one of the linkage elements.

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Marktheidenfeld, Germany

Heinz Schulte