Bw Hydraulik Gmbh

Hartmann & Lammle Gmbh Co., Kg

Ortlinghaus-werke Gmbh

Werner Kuttruf

Eckehart Schulze

Herbert Seeger

In a hydraulic circuit for controlling a clutch/brake system having a clutch that is disposed separately from the brake in a main drive of a mechanical press, wherein the brake is spring-loaded in a direction opposite to an engagement direction of the clutch, a piston/cylinder unit is provided that moves the clutch and the brake into a coupling position or a braking position, respectively. A pressure line connects a press safety valve to the piston/cylinder unit for generating torque at the clutch. A bidirectionally passable hydraulic connection connects a metering piston unit to the piston/cylinder unit in parallel to the press safety valve.

Hydraulic circuit

A device for limiting a working stroke of a hydraulic cylinder has a working cylinder and a working piston comprising a hollow piston rod connected to its top portion. A pressure reservoir is connected to a first working chamber for constantly supplying a pressure medium thereto, and a pressure source is connected via an inlet line to a second working chamber for supplying a pressure medium thereto. A shut-off valve comprises a push piston and a return spring for holding the push piston in its closed position. A drag link is slidably connected inside the push piston and extends through the working piston into the interior of the hollow piston rod. One end of the drag link has a first abutment that comes into contact with the working piston before the working piston reaches its end position. The other end of the drag link comprises an annular abutment which, when the first abutment is in contact, moves the push piston in the opening direction until a position of equilibrium is reached in which the working piston is hydraulically held in its end position. The shut-off valve is alternately actuatable by two actuating pistons.

Device for limiting a working stroke of a hydraulic cylinder

An electrohydraulic control arrangement for controlling a hydraulic cylinder having a double-acting working piston. At least one control valve having a control slide unit that is spring-loaded at one end and can be shifted by a servomotor against the spring force is provided. A valve housing having at least one section is provided with at least one control valve for alliance with each of the pressure chambers of the hydraulic cylinder, with the control slide units of the control valves being spaced from one another and being coaxially disposed in a mirror symmetrical manner relative to one another. A common control element of the servomotor is disposed between the inner ends of the control slide units for moving the same in the same direction. Each control slide unit has a pressure chamber containing an auxiliary piston, with at least one switching valve connecting these pressure chambers with pressure medium for moving the control slide units inot an inactive position that avoids the effect of the control element. This inactive position, or 'not-stop-function', can be directly controlled from any switching position of the control slide units. In the inactive position, the servomotor can be moved into its neutral position and adjusted without thereby causing movements of the piston of the hydraulic cylinder.

Electrohydraulic control arrangement for controlling a hydraulic drive

A hydraulic control mechanism to control operating elements, such as a hydraulic motor, or hydraulic cylinder, employing presetting of a set point, for example via a stepping motor, and mechanical feedback of an actual value. Functional elements are provided in the form of rotary pistons that fit inside one another, rotating relative to one another, and serving for the sensitive regulation of the direction and quantity of a pressure medium stream that is supplied from a pressure medium source to the operting element and flows back therefrom to the tank. One rotary piston is positively connected with the presetting of the set point, and the other rotary piston is positively connected with the operating element for the mechanical actual value feedback. In this way, in contrast to known control mechanisms where a slide or seat valve is actuated by a longitudinal movement, the rotational movement of the set point and actual value are directly compared with one another. This results in a considerably greater precision both statically (positioning precision, concentricity) as well as dynamically (sequence trueness, path deviation). The control mechanism is a better overload safety device, has a simpler construction, and is more economical.

Hydraulic motor control system with rotating servo-valve

An electrohydraulic control system for a hydraulic working cylinder, for example of a press, the piston of which has a main working surface and a smaller working surface on the rod side. A low-pressure circuit is provided for the feed or retraction movement of the piston, and a high-pressure circuit is provided for the loading movement at increased feed force and reduced speed. The connection or disconnection of these two circuits, when required, is produced with two 3/2 way valves that are coupled together. To control these control valves, there is provided an electrical reference motor that drives a cam disk which brings about the deflection of the coupled control slide valves of the control valves against a spring. A mechanical feedback is provided via the power piston, so that altogether a closed hydromechanical position control circuit is formed. If there is a difference between theoretical and actual values, this difference produces such a variation of the position of the control valves that via the control system of the low-pressure and high-pressure circuits connected therewith, the system endeavors to correct this difference automatically.

Electrohydraulic control system

Feeding device for the cycled feeding of rod or tape-like material into a press, cutter or the like, which includes a metering wheel which rolls off directly or indirectly on the material being fed, serving as a true value indicator. The metering wheel is coupled with a true value input metering spindle which acts upon a hydraulic control valve device. The exactly maintained feeding path is made possible by the mechanical coupling of the true value feeding with the true value input on the control hydraulic valve device.

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Wuppertal, Germany

Werner Kuttruf