Abstract: The invention relates to an electrohydraulic monitoring device for a dual effect hydraulic cylinder in which certain operating pressures must be maintained. A pressure reduction valve is provided for setting said pressures, this pressure reduction valve being used to set a defined pressure (41) by adjusting the pretension of the valve spring (41). The valve spring is situated in a spring chamber (137) which is bordered by a regulating sleeve (46) on one side, in an axially moveable manner. Said regulating sleeve is displaceable between two end positions within a limited axial stroke area. The alternative switching positions of a micro-switch (117) are linked to these end positions. Two sensor chambers, each of which is connected to one of the pressure chambers of the cylinder in such a way that they communicate, are provided and are delimited by sensor pistons (106, 107) in order to determine the operating pressure that is being coupled into the hydraulic cylinder at a particular time.

Abstract: A device for integrally joining a metal block (11′) that can consist of a number of plates, by hard-soldering or brazing. The hard-solder provides a connection covering a large surface and with a minimal thickness in solder gaps (17j; j=1, 2, . . . , n−1) located between adjacent segment plates (12i; i=1, 2, . . . , n). At least one capillary solder inflow path (14) is provided. Said solder inflow path starts at a solder depot containing a supply of hard solder or braze material (42), which melts as the stack (11) of plates is heated. The melted solder material flows directly to the individual, also capillary solder gaps (17j; j=1, 2, . . . , n−1) via said solder inflow path, the solder gaps being provided between surfaces of the segment plates (12i) that face towards each other.

Abstract: A valve system is provided for the hydraulic work system of a work vehicle, in particular of an industrial truck, with a elevating drive system for raising and lowering a load and a tilting drive system, each of which can be actuated by a control valve, in particular by an electrically actuated control valve, the opening width of which determines the speed of movement of the user. The elevating drive system is realized in the form of a single-action hydraulic cylinder and a check valve in the form of a seat valve that can be opened toward the hydraulic cylinder is located in a hydraulic line leading from the control valve to the hydraulic cylinder. The tilting drive system is realized in the form of a double-action hydraulic cylinder. The valve system has an improved function with low energy losses.

Abstract: A hydrostatic axial piston machine employs a swash plate construction in which the diagonal position of the swash plate can be controlled by at least one positioning piston pressurized with a control pressure. A control valve is in a line which leads to at least one positioning piston. A simple electrical-hydraulic control of the swash plate can be accomplished by the electrical actuation of the control valve. The control valve may be in the form of a rotary disk valve which can be actuated by a stepper motor.

Abstract: In a hydraulic valve (10), the housing (34) is composed of plate-shaped segments (36 to 46). Sections of longitudinal channels (96, 97) are formed by recesses having cross-section with a closed edge which overlap or are flush with corresponding channel sections of the adjacent channels. Radial channels, which are in communication with a supply connection (11, 12) or a consumer connection (13, 14) are formed by radial indentations (86 to 89) of central openings (75, 77, 79 and 81) of housing segments (38, 40, 42 and 44). Grooves (91, 92, 93 and 93) which widen the cross-section of the central housing channel (71) within which the valve piston (19) can slide in a pressure tight manner in the axial direction and/or rotation outwards are formed by recesses (75, 77, 79 and 81) of the housing segments (38, 40, 42 and 44) having a larger diameter and which positively overlap the central channel (71) in cross-section.

Abstract: A valve system is provided for the hydraulic work system of a work vehicle, in particular of an industrial truck, with a elevating drive system for raising and lowering a load and a tilting drive system, each of which can be actuated by a control valve, in particular by an electrically actuated control valve, the opening width of which determines the speed of movement of the user. The elevating drive system is realized in the form of a single-action hydraulic cylinder and a check valve in the form of a seat valve that can be opened toward the hydraulic cylinder is located in a hydraulic line leading from the control valve to the hydraulic cylinder. The tilting drive system is realized in the form of a double-action hydraulic cylinder. The valve system has an improved function with low energy losses. The check valve has a control surface that acts in the direction of the opening position and can be pressurized by the load pressure of the elevating drive system.

Abstract: A hydrostatic axial piston machine employs a swash plate construction in which the diagonal position of the swash plate can be controlled by at least one positioning piston pressurized with a control pressure. A control valve is in a line which leads to at least one positioning piston. A simple electrical-hydraulic control of the swash plate can be accomplished by the electrical actuation of the control valve. The control valve may be in the form of a rotary disk valve which can be actuated by a stepper motor.

Abstract: The invention concerns an electrohydraulic control valve arrangement (10) for controlling the movement of a hydraulic motor. The control valve arrangement (10) comprises a main control valve (11), which can be actuated by the alternating application and relieving of pressure in two control chambers, and an electohydraulic servo-control valve (14) which operates with electronically controllable piston setpoint input and mechanical actual position data feedback in order to pilot the main control valve accordingly in a manner guided by the setpoint value. The servo-control valve (14) comprises a sleeve-shaped housing element (99) which is disposed so as to be moveable in a pressure-tight manner in a connection block (114) rigidly connected to the housing of the main control valve (11).

Abstract: A hydraulic drive unit has a tracking regulator valve (19) for controlling a servo drive (18) of a main control valve (16), where the main control valve controls flow to a hydraulic motor (11). The tracking regulator valve is controlled by an actuating element (42), which is controlled by a comparison of a nominal position value, set by an electric motor (36), and an actual position valve, generated by a mechanical feedback (53) connected to the hydraulic motor. The main control valve includes a slide valve piston (87), which forms a housing for the tracking regulator valve, which has two piston slide valve elements (39, 41). The slide valve piston (87) of the main control valve (16) has an axial through-bore (122) through which passes the actuating element.

Abstract: The invention is a press for cold working of metal workpieces. The invention includes a double-acting linear hydraulic power drive cylinder, a continuous press frame for accepting reactive forces that develop during the operation of the press, and a control valve system operable by output signals, and being one of program-controlled or manually triggerable, from an electronic control unit, for controlling motion of a piston of the drive cylinder.

Abstract: A workpiece being processed on a machine tool is moved by control devices to the tool head or work station of the machine mechanically or automatically. A stop defines an area around the work station from which the holding devices must be kept to prevent damage. As soon as a holding device reaches the limit of the danger zone around the tool head, it is switched into a setting releasing the workpiece and moves into a position away from the work station. The machine has a switching element connected to each holding device to be so movable, and the switching element has a switching slide which is acted on by an applied force and is supported in a first position until it abuts the stop when one slide position connects the energy source to the drive of the holding device to move it away from the stop. In another slide position, the connection to the energy source is broken and the holding device returns to the workpiece holding position.

Abstract: A magnetic valve having spring-centered basic position, with a pulsed current of a relatively high frequency flowing through each of two exciter coils for setting alternate excited functional positions and for setting defined flow-cross sections in the respective functional positions. The pulsed direct currents undergo square-amplitude modulation so that current flows through the exciter coils alternately for time intervals T.sub.1 and T.sub.2. The frequency of the amplitude modulation having a period T is equal to a sum of the excitation time intervals T.sub.1 and T.sub.2 of the two exciter coils and is approximately 400 Hz. The magnetic valve has a central position rigidly mounted in a housing of the valve and a moveable valve element in a form of a soft iron sleeve which is also an armature of a double-stroke magnetic system. The functional position and deflection of the armature are chosen as a function of the ratio T.sub.1 /T.sub.

Abstract: A hydraulic drive in accordance with the invention includes an axial piston hydraulic motor provided for forming a power drive with a follow-up control valve provided for controlling the pressure medium supply with the follow-up control valve being electronically controlled by a desired position value presetting and mechanical actual position value acknowledgement. An electric motor is provided for the desired position value presetting which can be activated by output signals of a central CN or CNC control unit. The rotor of the axial-piston hydraulic motor is rotatably supported with a circular-cylindrical tubular section of an output shaft thereon on an outer casing surface of an axial extension which is a hollow tubular shape and forms a pivot pin for the rotor of a housing section accommodating the electric motor provided for the desired value positioning control.

Abstract: A process is disclosed for controlling the revolutions of the spinning roller (29) of a spinning lathe (10). The coordinate driving units (52,53), which are designed as valve controlled (49,51) hydrocylinders (42,47), are operated according to a playback process according to which the coordinate driving units (52,53) are operated according to a follow-up process in which position set values are electrically preregulated and mechanical real values are fed back. The slowing down path .DELTA.S (lag error) is continuously measured at least during the last revolution of the spinning roller (29), so that when a threshold value .DELTA.Smax is exceeded, the tracking speed V.sub.B is reduced and/or a transitioning to an intermediate routing curve occurs. A spinning lathe for carrying out the process is also disclosed.

Abstract: A hydraulic control system for the drive control of a double-acting hydraulic cylinder with a larger driving surface and a smaller countersurface, in which the direction- and movement-controlling valve is provided in the form of a follow-up adjusting valve that operates with an electrically-controlled indication of the set value and with a mechanical announcement of the actual position. The pressure source provides two different supply pressures P.sub.N and P.sub.H. A pressure-controlled pressure-reversing valve is provided to switch to the higher supply pressure as and when this is called for by a growing load. A similarly pressure-controlled surface-reversing valve is also provided and, after the pressure-reversing valve has switched to the higher pressure, will itself switch the hydraulic cylinder from a differential operating mode to a mode in which pressure is applied only to the larger working surface of its piston.

Abstract: A hydraulic drive mechanism for a punching or an embossing tool, with a double-acting drive hydrocylinder with differently large piston areas, the rapid feed operation, the working feed operation, as well as the rapid retraction operation being controllable by the joint or alternative pressurization of these piston areas. For effecting switchover, an area switching valve is provided which switches over, once the driving pressure exceeds, for example, 90% of the maximum initial pressure of the pressure supply unit, from differential operation to unilateral pressurization of the larger drive area. The area switching valve comprises a check valve acted upon, in the opening direction, by the operating pressure in the smaller driving pressure chamber. A locking spring force of the check valve is equivalent to an opening pressure of about 90% of the supply pressure.

Abstract: Hydraulic drive mechanism for a machine element with rapid feed movement and under-load feed movement, comprising a double-acting hydrocylinder power drive and a pressure switching valve responding to the pressure at least in a larger operating chamber of the hydrocylinder when the pressure in the operating chamber exceeds a threshold value higher than 1/4 of the operating pressure of the pressure supply source, but lower than half the operating pressure thereof, switches to under-load feed operation and, when the pressure in the drive pressure or operating chamber falls below the threshold value, switches back to rapid feed operation. The pilot valve for the main control valve is equipped with two windings effective in opposite directions.

Abstract: A system for monitoring the position of a machine component, provided with an electrohydraulic drive system which, in order to control the forward and backward movements of this machine component, comprises a follow-up adjusting valve that operates with an electrically-controlled indication of the set value and with a mechanical announcement of the actual position. The monitoring system is provided with a mechanical conversion device which converts the deflections of the servocomponent of the follow-up adjusting valve into larger deflections, correlated therewith, of the mechanical operating element of a proximity switch which, seen in the deflection direction of its operating element, is arranged at a defined distance in relation to the position adopted by the operating element when the servocomponent of the follow-up adjusting valve is located in its characteristic basic setting for equivalence of the set and actual value.

Abstract: A hydraulic idling-regulating valve comprising at least two mechanically operated through-flow valves which can be controlled to move alternatively into a flow position and a closure position and which are both closed in a neutral central position. An electromechanical specified-value setting system positions the piston of a hydraulic drive cylinder, which system comprises a hollow shaft that can be rotated by a number of revolutions correlated with the specified value, and an actual-value feedback system is provided which comprises a feedback spindle which is in engagement with an internal thread of the hollow shaft and which performs a number of revolutions correlated with the piston movement. The valve-actuating element is subjected to the same displacements as the specified-value setting shaft.

Abstract: A hydraulic drive system for a machine element performing in one work cycle a sequence of motions comprising a rapid feed motion, a working stroke under load and an oppositely directed rapid-return motion. The drive element includes a hydraulic cylinder having three working surfaces A.sub.1, A.sub.2, A.sub.3. Motion control is effected by an electro-hydraulic follow-up control valve with a pre-setting device controlled by a stepping motor and a mechanical actual-value feed-back device. During rapid feed motion, the relatively small working surface A.sub.1 is subjected to the output pressure of the follow-up control valve only, while during the working stroke the pressure acts additionally on the working surface A.sub.3. The rapid-return movements of the piston of the cylinder are controlled by applying pressure to the working surface A.sub.2, or by relieving pressure from the two other working surfaces A.sub.1 and A.sub.3.