DE860752C - Control device for hydraulic drives - Google Patents

Description

Control device for hydraulic drives For hydraulic drives, especially with hydraulic presses, the reversal is for changing The direction of rotation or stroke is often brought about by a T-Tm control slide, which the oil source, which is also often an adjustable oil pump, depending on the desired one Direction of movement to one or the other side of the rotating secondary part (Oil motor), which in presses and also in some: other drives often through a reciprocating piston working in a cylinder must be replaced can switch. In order to now deal with the great effort required by a Safety valve in its highest pressure development limited the pump at standstill or slow movement of the abutment would cause it to restrict used man: especially with surrounding valves, which are not like the so-called flow system in its central position the oil flow delivered by the pump with moderate counter pressure let flow through, but completely or almost completely through the delivery of the pump Interrupt the blocking of corresponding duct openings, one by changing the effective piston stroke adjustable pump, which is roughly similar to the one in the hydraulic Gear construction is also built in other customary controllable pump or oil motor parts and is supplemented by a suitable pressure regulator, which corresponds to # -dem Pressure increase the. Piston stroke of the adjustable oil pump except for small ones, for the maintenance the necessary operating pressure. still required minimum amounts reduced. at this well-known: establishment. is now due to the regularity of the .Pumpfeed considerably in energy compared to the corresponding with non-controllable pump and Safety valve working device saved. However, the disadvantage remains that at standstill and: slow movement of the secondary part or the press cylinder in the hydraulic press the pump must always develop the full maximum pressure, as he often only exceptionally or for a short time with greater resistance to movement on the secondary part, in presses often only at the lower end of the stroke. This gives an undesirably high level of stress, which can often be regarded as almost permanent the pump, which the choice of a relatively low utilization of the adjustable Pump forces, as most of these pumps are temporarily or infrequently overloaded a multiple of the pressure that is permissible continuously or over long periods of time without To be able to endure harm. Incidentally, the effort required is already the Such pumps, depending on their design, also for achieving the highest pressure require small funding, often not entirely insignificant.

The well-known, with reversing spool and adjustable pump with pressure control their promotion (whereby often also a strong dependency on the operating pressure is carried out by the flow rate) working system can therefore by no means the Energy efficiency and: also: not the high load capacity either known hydraulic drive system that works without a reversing spool in the main circuit Achieve, in which the for reversible, so not just adjustable funding set up Primary pump directly via two pipes or channels with the secondary part, or else with the press cylinder depends and the reversal accordingly, under Taking advantage of the reversal of the flow direction of the pump is going on.

This well-known, a cheap energy economy and a high utilization the hydraulic transmission resulting system, which mostly as a closed circuit is referred to, but has the disadvantage that for the actuation of the reversing necessary stroke adjustment of the primary pump usually a special auxiliary motor is necessary because this stroke adjustment usually requires greater forces and standstill or a change of direction usually has to take place very quickly. Furthermore, it just results in presses, which are often used for the various phases of movement of the press cylinder Use different sized piston areas, the difficulty here is that again special valves, usually also requiring their own control, and others Measures are necessary to cope with the changing oil content of this drive system to give the necessary compensation option with an appropriate oil container.

The present invention now shows a way in which one can while maintaining in many cases because of its easy handling. 'preferable Reversing slide and one that can only be regulated, not also for changing conveying direction Pump to be controlled or, in short, while maintaining the open, with reversing valve working cycle, the same and in some cases even higher economic efficiency and .the same usability of the hydraulic parts as in the aforementioned closed Cycle can achieve. According to the invention this is achieved in that with the Reversing slide a device is connected, which when approaching the reversing slide in its central position instead of the known pressure control of the pump, one of these Control slide setting: setting dependent influence on the stroke or pressure setting the pump causes in the sense that in the vicinity of the slide center position in which the slide is known to throttle the fluid channels to a greater or lesser extent or even completely shut off, only small values of the pump pressure or smaller Values of the pressure developed by the pump can and in any case occur which is actually quite unnecessary in the context of this invention for practically all drives and the development of the maximum pressure in the slide center position is omitted.

Compared to a known device in which the reversing slide actuating mechanism, such as a hand lever at its stroke end, mechanically on one acts on a controllable pump attached pressure regulator and thus to Induced development of higher pressures, there is the advantage that instead of this mechanical control of the pressure regulator, which requires a lot of force is used to change the pump setting, so that one as well easy operation like an ordinary one working with constant = high pressure Reversing slide is achieved. Furthermore, the adjustment according to the invention of the pressure regulator in view of the relatively small required for this Forces easy like this: set up, d, ate them already near the slide center position occurs during the direct mechanical load on a pressure regulator requires greater effort due to the setting tool itself and is therefore practical only at one or both ends of the stroke by one acting on the pressure regulator. Stop can be realized ..

Fig. I: shows an embodiment of the invention. i is the adjustable pump, which draws a suitable liquid, mostly oil, from the oil container 2 and into the pressure line q. promotes. The reversing slide 5 controls the secondary part (oil motor) of a hydraulic drive or, as shown in FIG. Depending on the application, this can have different, large piston surfaces ines open circuit with slide reversal for forward and backward movement, without this having to take any special precautions; would require. For the controllable pump i, too, any of the known controllable pump types, such as are customary in hydraulic gear construction, can be used. In Fig. I, for example, the known controllable pump is shown in which the in: suitable manner. driven drive shaft 3 about an invariably fixed axis in space or, in short, fixedly rotated and a pivotably rotating cylinder block, which is held in the pivot frame 8, determines the size of the liquid delivery with its pivot angle. As usual, the delivery of this pump is determined by a pressure regulator 9. Deviating from the known embodiment, however, according to the invention this pressure regulator 9 is influenced by the position of the reversing spool 5, in such a way that unnecessarily high operating pressures are created on the pump i or in the pressure line 4 in continuous operation and in particular also in the environment the drawn center position of the reversing slide 5 is avoided. For this purpose, for example, the pressure regulator is designed twice as 911 and 9b. The for example single acting against a common spring ii acting pressure piston ioa and job of both pressure regulators act in a known manner on the Sbellzeug of the controllable pump i, in this case on the swivel frame 8 or an associated extension 12, which is also the holder of the Spring ii serves. The first pressure regulator 9a is a conventional pressure regulator which is directly connected to the pressure pipe 4 and which is dimensioned for the briefly permissible maximum pressure of the pump. According to the invention, it can now be set up in such a way that when the maximum pressure is reached and at a standstill or when the plunger 7 is only moving slowly, it tips over into an operating state with a lower pressure. For this purpose z. B. the lower part of the plunger. ioa provided with length and transverse bores 13 and 14, which after setting the pump to a small Hiibe allow the high pressure to enter under the enlarged head of the pressure piston ioa and thus reduce the operating pressure accordingly. A throttle opening 15 ensures that after reversing the press or in the case of a rotating drive after complete or approximate reaching standstill and reversal of movement, the original overload capacity can be achieved again according to the smaller lower piston area of the pressure piston: the one in the specified manner as a double-stage Pressure regulator 911 already implements the basic idea in a certain way: the invention, according to which, depending on the position of the reversing slide 5, the delivery of the pump i should be reduced, but its pressure development should also be limited as soon as the reversing, control switch 5 is in F .ig. i drawn center position is approaching. Especially when in this central position this slide valve closes the oil ducts completely "or somewhat"furiously; each time when it approaches: its central position creates a pressure peak which is immediately reduced by the double-step design of the pressure regulator: However, the invention can also be implemented in this way; that there is no longer any short-term pressure spike; if one approaches the Umstenerschi, about 5 of its middle position, without having to build about such a slide with larger, open flow cross-sections in the middle position or, in short, as a flow slide, which due to its large liquid requirement also with moderate Operating pressures would cause greater losses and would also be difficult to reconcile with the pressure gradation, which is dependent on the delivery rate, as shown by the pressure regulator 911 in FIG.

In Fig. I this effect is now achieved by the second pressure regulator 9b, which with a correspondingly large. Piston Job is equipped and already at. a suitably selected low pressure in its pressure control system 16 reduces the pump delivery. So that this only comes into effect in the vicinity of the central position of this Ums.teuerschiebers 5, he is on the; Auxiliary slide 17 connected to the main pressure line. The help-. The slide is connected to the reversing slide 5 via the rods drawn, in particular the triangular lever 18, so that the connection between the pressure control line i # 6 of the pressure regulator 9b and the main extiruak line 4 is only established when this reversing slide 5 is in the middle. This is achieved as follows in the embodiment of FIG. At both stops can. but it only rest in the drawn central position of the Umsüeoerschiebers 5. If this is moved upwards, the lower end of the triangular lever 18 leaves the stop tob and, conversely, when the reversing slide 5 moves downward, the upper end of the same leaves the stop 2oa: In both cases, the pivot point 21 moves to the right and thus also moves the auxiliary slide 17 to right, whereby the pressure regulator 9b disconnected from the pressure line 4 and onto the drain line 22 and thus. is switched to the completely or approximately pressureless oil tank 2. In this way, the pressure regulator 9b, with its pressure setting that is low from the start, is rendered ineffective, and the pump i @ can now develop high pressure in accordance with the device of the pressure regulator 9a already described.

In many cases it is useful to activate the auxiliary slide, 17, which serve: low pressure regulator 9b switches off; not just from that. Um-: süeuerschieber, but also from other company sizes, e.g. B. from the stroke setting or To make the delivery rate of the pump r dependent. In Fig. J the return lever serves this purpose 23, the lower end of which, for example, by means of the angle lever 24 with the swivel frame $ the Pump i or the extension attached to the swivel frame 1a is in connection.

In this device, as shown in Fig. I for the low pressure regulator gb is shown, this does not act as a pure pressure regulator, but as a. position = dependent pressure regulator, with the rigidity of the to be determined appropriately Spring i: i helps determine the behavior of this pressure regulator.

But it is also possible to use the low pressure regulator gb as a pure positioner, more precisely to work as a pure servo motor. let which one depends on the Deviation of this Umrsteuerschiebersi 5 from its central position only certain advertising the largest stroke of the pump i and thus the pump delivery permitted and otherwise but the operation of this high pressure regulator ga in no way hindered.

To achieve this, it would only be necessary in Fig. I, the pressure supply opening a5 on the auxiliary slide 17 instead of the main pressure line q. with a stranger, enough productive or sufficient: high pressure oil well, such as a special one To connect gear pump, as it is often used for such controls.

Practically the same thing is achieved by calving the Low pressure regulator makes gb so great that even the lowest; Values of the operating pressure its strength is still sufficient to operate the pump i. to produce sufficiently small delivery quantities. Such a stroke size or delivery rate are used by the pump i as a function of the Deviation of the reversing slide 5 from its central position restricting device is particularly satisfactory in its effect when the reversing slide 5 executes in a suitably dosed measure as a flow valve, for example in the case of an ordinary, with sufficient overlap executed Umstewerschieber in the control edges KnownAusfräsuugen attaches, through which, in addition to elimination, the disturbing insensitivity a reversing slide valve 5 with a larger overlap also in the Mittelhage of the scraper a metered flow rate is used by the pump 'delivered liquid what can be achieved together with the declared, appropriately chosen limitation the stroke setting of the pump to a specific pressure limitation for this comes out.

There are, now, cases in which at all only for one direction of stroke or movement the secondary part requires actual high pressure; z. B. in a Preßzylirnder 6 as he in; Fig. I is shown, sometimes only, for the downward movement really high pressure needed. In this case the stop aob can obviously be omitted or, what comes to the same thing, the triangular lever 18 can by a one, -fold angle lever to be replaced; a stop 2oc on the auxiliary slide 17 can then perhaps be useful to move this too far to the left To prevent pushing. Da, ß here to avoid linkage breaks In some circumstances also spring force connections in; the linkage may be necessary - is Just like many other measures known in control engineering are a matter of course, which actually needs no special mention.

In order to achieve the effect according to the invention, it is also with drives, which only require one-sided high pressure development, only necessary, a j accordingly set only one-sided acting device similar to Fig. i so that the pressure-limiting Effect of the pressure regulator gb still in the vicinity of the central position of the reversing spool 5 is effective and only then by the corresponding displacement of this auxiliary slide 17 is eliminated when the controlling knowledge of the reversing spool 5 is for have opened the relevant direction of movement so wide that now the increasing Delivery rate of the pump i without excessive energy-consuming throttling of this jini control element 5 can go through.

The same applies if, as already explained above, the pressure regulator gb in Fig. i does not act as the actual pressure regulator, but entirely or partially as a servo motor, which adjusts the stroke of the pump i and its delivery rate in the vicinity of the Slider center position limited and about. so in connection with suitable flow properties or leaks in the slide the high pressure development of the pump i in the Slide center position or the disadvantages of the known ones explained in the introduction Eliminated slider buckling.

Of course, this effect according to the invention can also be purely mechanical Achieve ways by using the steep equipment of the reversing valve a suitable mechanical Device, such as a triangular lever according to FIG. I or a cam disk, see above connects that the stroke of the pump is limited in the central position of the slide. As a rule, however, such a mechanical stroke resetting would be too stiff fail, so that a servo motor of some known type is necessary, and in many cases the hydraulic servomotor is very often in his for this Training as a pressure regulator the most appropriate solution.

Otherwise, the details of the embodiment described are immaterial to the invention. For example, the ums, control slide 5 in Fig. I or the auxiliary slide 17 can be replaced in a known manner by valves, for example also by valves, which are controlled by a common camshaft in such a way that they replace the action of a slide. Furthermore, meow can, for example, give the low pressure regulator gb an outlet throttle opening similar to 15 at ga., And then the slide 17 can be simplified so that it only opens and shuts off the connection of the pressure oil, eitunig i6 to .4 in an analogous manner; it can then also be replaced by a simple valve.

Finally, the two pressure regulators ga and gb in Fig. I combine with each other in many ways. Even. when using a single Pressure regulator 9a, as it was described above: effects can be achieved, which at dien in Fig. 1 shown embodiment only through both pressure regulators can be achieved. For example, an auxiliary slide similar to 17 in FIG usable wine to the pressure regulator 9a parallel to the throttle opening 15 a another larger outlet to release opening; with that one could achieve that in case of displacement of the reversing spool 5 from its central position always the high pressure development again the pump is initiated. If the pressure control line 16 is also used to to pressurize the larger piston of the pressure regulator 9a, so is by a single pressure regulator in the main achieves the same as in Fig. i with two Pressure regulators.

2 shows a corresponding embodiment of the invention. The main axes of this control device, such as pump i; Reversing slide 5 "press cylinder and pistons 6 and 7, are the same as in Fig. i and labeled as there. However, there is only a single pressure regulator 9, which, however, at least is carried out in two stages. Thereby, a pressure control line 16, which also Exactly as in Fig. i of a mechanically connected to the control slide 5 Slider could be switched under the larger piston io of the pressure regulator guided. However, in Fig. 2, for example, the effect of the separate auxiliary slide 17 with the triangular lever 18 in Fig. I by a attached to dien Umsteuerscbleber Auxiliary control device replaced. As can be seen in Fig. 2, this is set up so that that in its central position at 26 a connection between the pressure line 4, the Pump i and the Drucks.beuerleitung 16 is made, while vice versa only when shifting the reversing slide 5 from its central position upwards or below at 27 the Drucksroeuerle.itung is connected to the discharge line z2.

The same effect as in FIG. However, the dependency on the swivel angle setting of the pump i provided there is missing. If this is not dispensable or cannot be replaced by suitable determination of the stiffness of the spring m in conjunction with its appropriately executed creeping opening of the auxiliary controls 26 and 27, a return lever 23, as in FIG if one subdivides the reversing slide 5 shown in FIG. 2, approximately at 28; or you can, especially in view of the lower oil requirement of the auxiliary control 206, and 2; 7, the usual means in fuel pump construction for shifting the controlling edges at 26 and 27, that is, inclined or helical edges on the slide at 2, 6 and 217 and in the valve body control orifices of limited size. in the circumferential direction of a rotatable reversing valve 5, which then with its angle of rotation position results in the desired dependency of the -DruckreglereinstelIüng when this or a rotatable slide sleeve part is brought into connection with a suitable return linkage with the pump pivot angle.

If you also bring transverse and longitudinal bores 13 and 14 in the pressure regulator disc of Fig. 2; similar to the corresponding Biohrungenbeiga of Fig. i, so lets the corresponding overload protection can be achieved in a manner similar to that in FIG. included can also be attached to the Aus.laßdrasselöffnung 15, if you have this still considers necessary; the interaction of such, so to speak, multiple times effective controls can be coordinated in the desired way, why only the productivity of the individual liquid streams, for example through suitable ones Choice of cross-sections of control organs or pipelines; by installing throttling points or to determine other known means appropriately.

In this sense, the invention, whatever pressure or limitation, can be for the controllable pump for the central position of the Umsteuersdhiebers 5 required, too with a single-stage pressure regulator '. If) z. B. in Fig. 2 the high-pressure line 4 through the high-pressure throttle point 29 undribbled around the large piston of the pressure regulator 9 is guided, it can be adjusted by appropriate setting This Drossels.teelle also achieve the desired high pressure setting of the pump i, if the small high-pressure piston on the pressure regulator is completely missing or only, approximately in small dimensions, the Über_lastungsverschnaltumg with transverse and longitudinal bores 13 and 14 has to be accomplished. So as not to be simplified with this. Execution of having to accept excessive high-pressure oil losses, one becomes; Indeed or choose the Aus.laßdrosselstel.le i5 accordingly. the outlet, control 27 still throttle accordingly; especially in this case it also makes sense to have a to omit these two institutions entirely.

The pressure and output shown in Fig.2: B control 26 and 27 loads Of course, arrange themselves in such a way that they only have a one-sided effect, as is the case for a press that requires high pressure only in one stroke direction is appropriate. In this case, the same applies analogously to the description of the design and setting the unilaterally acting: auxiliary control 17 of Fig. i was said.

Influencing the promotion or pressure development according to the invention a controllable ::. Primary pump from the middle position of a reversing element l: äß.t himself in; in some cases. advantageously combined with burners, which z. B. in the case of hoist drives, the load crashes in the low pressure development connected central position of the reversing. Prevent slide. If the reversing valve is as mentioned earlier, z. E.g .: as: flow valve, d. H. leaking in his If the middle layer is made, such a brenisie can be particularly useful. It can be operated mechanically or hydraulically: -vomr däfii `Ü-3rieüerarhüeher ..derived . will. For example, the brake 30 is shown in FIG. 2 connected to the pressure control line 16 for the purpose of hydraulic actuation; a spring ig ensures that the brake is withdrawn when the reversing slide valve is open Leaves central position.

An example conveniently based on the operating conditions also has similar purposes adjustable stop 2o in Fig. 2 to serve, which a certain minimum amount the delivery of the pump forces or the occurrence of a reverse delivery direction the same prevented. If this stop with the spring 31 as a resilient stop executed, a certain minimum pressure development for small promotions m one of the intentional or unintentional leaks of the system or in particular of the reversing spool less.highly dependent manner achieve.

In general, the invention can be deviated from those described in more detail here Embodiments vary in many ways with the use of known tools, without their basic idea, namely the energy-saving and maximum usability the influence of the hydraulic parts on the delivery rate or the pressure development a controllable pump depending on the setting of a reversing device to become unfaithful in its central position. If this facility is now also in can primarily be used for reversible drives, it is clear that that in some cases it is only for those that are to be stopped and not also to be reversed Drives can be advantageous, since they also have the known arrangements have the same defects, e.g. B. the drives with reversing spool and pressure-regulated Pump the mostly completely unnecessary development of high pressure when the vehicle is stationary. In this Case can instead of the reversing spool or the z. B. with a cam shaft actuated four reversing valves enter a much simpler control device. In many cases, a simple gate valve or shut-off valve is sufficient for the hydraulic fluid supply, as the shut-off of the fluid drain from the Working cylinder or the rotating servo motor is apparently only necessary when braking is required, including another valve, another slide or a correspondingly set up common slide would be necessary. But it is it is clear that in these cases, too, the application of the invention is advantageous; as well is the expedient way of their execution too. in these cases from the example selected, suitable for a reversal control devices according to Fig. i or 2, as this only applies to the corresponding blocking of the hub of the reversing slide 5 for a corresponding side to be determined outside of his Central position depends on leaving out what is no longer required mechanical or hydraulic precautions.

In some cases: with an adjustable stroke adjustment Pump the hydraulic drive only by opening an outlet valve on the pressure line the pump stopped. Especially if there is still a pressure regulator on the pump control kit acts, this has the disadvantage that continuously and unnecessarily large flow losses occur when the system is at a standstill. It must also be the starting point for a real shutdown can be made very large without achieving too high a back pressure. In such a In this case, the invention can be carried out very advantageously in the manner shown in FIG. 3 will. i is a controllable pump there, somewhat similar to the one described in FIGS Pumps' one with a pivotable frame 8 and: more solid, suitably driven Drive shaft 3. The swivel frame 8 is driven by the force of the spring i i against the pressure regulator piston of the pressure regulator g pressed, with which, for example, here mainly an overload protection the system is achieved without having to accept the disadvantages of a safety valve. An adjustable stop 2o, which limits the stroke of the pressure regulator piston, or any other manually or automatically of any size . adjustable stroke influence of the pressure regulator g can .this for the purposes of Serve control of the drive. The secondary part is here, for example, a similar one rotating like the pump, possibly also adjustable in any way Oil motor 32.

In order to shut down the drive, the relatively small one is used Control slide 33 is initially moved down from the position shown, that the adjusting cylinder 3.4, which was previously connected to the oil tank, pressure from the pressure line 4 receives. He then brings; opposite. the action of the spring i i through the drive Adjustment of the stroke of the pump to small values to a standstill, whereby one of the actuating cylinder 34 parallel, switched brake cylinder 35 with brake piston 36, which on the Brake disk 37 acts. brings the drive to a complete standstill when its load is not sufficient to this despite the effect of the tension of the spring i i resulting residual pressure. to hold on. So that this residual pressure is not too big must be, it can be very useful here, the tension of the spring i i proportionately to choose weak or this in the drawn horizontal structure by a simple weight effect, such as replacing the dead weight of the swing frame. A weak pen i i? can also be arranged in particular when another smaller adjusting cylinder 34a, which, for example, is permanently connected to the pressure line: g4 is, this supports.

The device shown in Fig. 3 has compared to the arrangement a simple exhaust valve has the advantage that a control slide of small dimensions is completely sufficient to take advantage of an often without this, for example, the Overload protection serving pressure regulator to bring about the shutdown of the plant. According to the invention, a special low-pressure regulator is then used for this shutdown of the system used _ or also according to the embodiment according to Fig. a multi-stage or adjustable by changing throttle points, etc. Pressure regulator, so that it is not necessary to shut down, the pump is constantly yours Develop maximum pressure to let anything other than those described in the introduction Disadvantages of the known control devices would also have the disadvantage here that the brake required to hold the secondary part would have to be very strong.

In some cases, such a brake 30 in FIG. 3 is also desirable in order to hold the secondary part 32 firmly when the system is at a standstill, even when the system is shut down. In this case, you will not choose a spring return for this brake, but a spring or weight pressure for this brake and perhaps additionally or exclusively an actuating cylinder that lifts the brake when a certain minimum pressure occurs in the pressure line .4, if the The control slide 33, which is to be changed accordingly, is in the operating position. Instead of this, the lifting of the brake can also be left to other known mechanical, electrical or hydraulic devices, including a device of this type that is tachometrically connected to the drive of the primary pump Similar mechanical or hydraulic or also electrically operated locking devices are used. In the embodiment according to FIG. 2, for example, the blocking of the stroke of the plunger, in particular to avoid its slipping under its own weight during a long standstill, can be a mechanically, electrically or hydraulically actuated valve in the lower position depending on the reversing slide position Serve connecting line of the press @ cylinder, which can be carried out more easily than the Umstenerschieber 5 completely tight. With the control according to Fig. 3, in addition to the device shown, which is only used for stopping, a known type of reversing device could also be used, for example a non-relieving and therefore simpler and lower flow loss having a path-like reversing valve (3.8 in Fig. 3). Instead, you can; There, the reversal can also be carried out by an oil motor that can be adjusted from I to II to the opposite direction of rotation.

Control slide 33 and reversing member 38 can also have a common Received actuation in such a way that the reversing organ not relieved always only in The low-pressure state of the system is adjusted. This purpose can, for. B. the in Fig. q. The device shown in a schematic, perspective view is used. The hand lever 39 adjusts the camshaft 4o here; the cams are shaped so that the adjustment of the to the lever 38 'in Fig. q. to be attached urn control organ only with the low pressure setting this control slide 33, which is operated via the lever 33 ' is operated, is going on. Otherwise: the invention relates mainly on hydraulic drives with a pump that can be regulated by stroke adjustment. It's jet high possible in appropriate cases. with a secondary part that can be regulated by adjusting the stroke achieve similar effects; a. Drive with constant torque load z. B. in a hydraulic transmission an inversely proportional to the secondary stroke Operating pressure. It is therefore also possible to apply the invention to drives in which a pressure control by adjusting the secondary stroke alone or in combination is achieved with a primary stroke adjustment.

Otherwise, the pressure regulators are simplest in the exemplary embodiments Design shown, consisting of a liquid pressure to be regulated or a certain fraction of the same standing pressure cylinder, which against the Force of a stroke enlargement of the pump causing spring is balanced. Especially since for larger versions you will get out here. Sizing reasons still known or attach nearby pilot controls. Now there is the special design of the pressure regulator like most of the structural details chosen for the invention, for example If such variants are insignificant, it is not necessary. of execution here to be described in more detail.

Claims (1)

CLAIM OF THE PATENT: Control device for hydraulic drives with a primary pump that can be regulated by adjusting the stroke or an oil motor that can be regulated in the same way and a multi-stage, or adjustable, by adjusting the stroke; Pressure regulator, which either influences the operating pressure of the system continuously or within the scope of delivery or the ability of the primary or secondary line to absorb, or which only serves to protect the drive from overloading in a known manner; characterized in that when the drive is shut down or reversed, the pressure regulator is set to lower values of its pressure setting or, as a servomotor, it influences the stroke setting in the sense of a lower pressure effect, whereupon the hydraulic drive is shut down or reversed when the value of the pressure regulator is reduced by the pressure regulator influenced in this way Operating pressure is going on; be it due to the drive's own power requirement, an additional brake or a special one. Shut-off or reversing device provided in the hydraulic drive.