EP2011605A2 - Hydraulically activated hand tool - Google Patents

Abstract

The tool (1) has drive elements for driving a working head (2) provided in a body unit. A switching movement allows a powered movement of the working parts of the working head to be triggered. The working head is swivelably connected to the body unit in a rotary connection region. The rotary connection region includes an axis of rotation, where swivelling of the body unit relative to the working head about the axis of rotation allows a switchingover movement to be carried out with respect to the powered movement of the working part.

Description

The invention relates to a preferably hydraulically actuated hand tool with a working head and a contrast remaining trunk device, wherein in the trunk device for driving the working head drive elements are provided, for example, a hydraulic pump and a hydraulic reservoir, further by a switching movement, a force movement of one or more working parts of the working head triggered is and the working head with the torso devices in a rotary connection area is rotatably connected.

Hand tools of the type in question are known, in addition to conventional, two-hand, further example, electro-hydraulically operating hand tools in lighter version for one-handed operation. Such hand tools are used, for example, in the sanitary area for pressing pipe joints or in the electrical area for pressing cable lugs on electric wire ends. With the lighter one-handed hand tools, hydraulic forces of, for example, 3 tons are achieved. In this context, for example, on the DE 10216213 A1 directed. The content of this patent application is hereby incorporated in full into the disclosure of the present invention, also for the purpose of including features of this patent application in claims of the present invention.

In the known hand tool, the working head is connected to the trunk device via a thread. But this only to make an exchange of a working head, if necessary, or to carry out maintenance. The working part is a pivotable pressing jaw, which can be moved by hydraulic movement of a working head associated piston against an example fixed jaw.

In addition to such hydraulically operated hand tools and electric motor-operated hand tools of this type are known. This is about on the DE 202006001301 U1 and the DE 2709946 C2 directed. Here, the working parts consist of power-operated pressing jaws.

In the known hand tools, a feed movement, that is a force actuation of the working part by hydraulic pressure or, for example, a spindle adjustment by means of an electric motor causes. For this purpose, a first switching operation with a switch button is required. Another movement of the working part, in particular a return movement after work, so for example after completion of a compression, often takes place automatically, namely on the triggering of a return valve out at a hydraulic device, or must by another lever or switch operation, the latter at about one electrical device, to be triggered.

In particular, in difficult conditions of use of such a hand tool, such as on construction sites or in the mining sector, is looking for an operation that requires a clear and clear handling.

Based on the above-described prior art, the invention has the object, a hand tool of the type specified in such a way and further, that safe working is ensured by means of a clear and clear handling.

A possible solution to the problem is given by the subject of claim 1, wherein it is pointed out that by a pivoting of the trunk device relative to the working head about a given in the rotary connection area of the working head to the fuselage rotation axis switching with respect to the force movement of the working part is feasible. Such an embodiment is particularly suitable if, due to the Operating conditions of the hand tool is given a rotational blocking of the working head. On the other hand, you can also come to a two-handed operation by holding the working head or the trunk device and twisting the other part of the device. Here, the operation is given priority in the sense of switching, that is, a direction of movement of the working part can be influenced or reversed. Regardless of this, it can be provided that the workability of the handset as such, so in the case of a hydraulic device, the work of the pump can be started by a separate button. With regard to the rotary connection area, the already existing in the known devices threaded connection can be used. As explained in more detail below, precautions can be taken that it does not involuntarily come to a complete unscrewing of the working head. On the other hand, a separate rotary connection region can also be provided independently of the threaded connection, in which case there is no axial distance change between the working head and the trunk device in the course of a rotation.

Further features of the invention are explained below, also in the description of the figures, often in their preferred assignment to the subject matter of claim 1 or to features of further claims. But they can also be in an assignment to only individual features of claim 1 or the respective further claim or each independently of importance.

Thus, a preferred embodiment is also given by the fact that a pivoting position between the working head and the trunk device can be fixed. For example, in order to be able to effortlessly maintain the same pivoting position over several work processes. Or also, in order to maintain a secure pivoting between the working head and the trunk device in the course of then taking place power operation of the working part.

In further detail, it is also provided that the hull device has a first piston, which pivots in the course of the switching movement about its longitudinal axis extending in the direction of movement. This is usually achieved by a direct rotational coupling between the hull device and the first piston. Thus, the pivot position of the first piston can be used to the desired switching. This then also in that influenced by the possible longitudinal movement of the piston, the circuit with, for example, only secured, is.

It is also preferable that the aforementioned first piston can be coupled with the working head. It is an immediate coupling between the first piston and the working head achievable. The coupling can thus be limited to the already longitudinally movable part, the first piston and the associated region of the working head. Particularly preferred in this context is that a pivoting position between the first piston and the working head by direct contact between the first piston and the working head can be fixed. The first piston can be moved against the working head and the case given plant on the working head also serves to fix the pivoting position.

The determination of the desired pivoting position is further preferably due to the hydraulic load of the first piston on the piston head facing away from the working head. The surface of the first piston opposite this piston surface is consequently pressed under pressure against the working head, after which a further pivoting is possible only after the pressure on the piston has been reduced. In this case, a sufficiently high frictional force of the superimposed portions, for example. End faces, the cooperating portions of the piston and working head reached. In addition to the purely non-positive definition can also complementary or alternatively a positive interlocking Set the desired pivot position of piston and working head sections. Alternatively, the fixing can also be achieved, for example, by the action of a spring force on the piston in the direction of the working head, moreover also by mechanical means, for example by a restraint of forceful release or the like. In the case of a spring action in the direction of the setting position, for example, a helical spring or the like can continue to act on the piston surface facing away from the working head. Such a spring force can be designed to be triggered, which triggering takes place after reaching the desired pivoting position between the first piston and working head.

It is further preferred that the first piston is pivotally limited relative to the working head, so on with respect to the piston longitudinal axis by an angle of preferably less than 360 °, for example in an angular range of 1 ° to 90 °, more preferably in a range of 10th ° to 300 °. In one embodiment of the subject invention, an angular adjustability of the first piston relative to the working head of about 15 ° to 25 °, so on, for example, about 20 ° predetermined. Preferred is an angular position that can be easily reached for the user from the wrist. Within this angle-limited pivotability of the first piston at least two different action functions of the working head are preferably adjustable. These two functional positions more preferably correspond to the pivot end positions of the first piston relative to the working head. In addition, intermediate positions of the first piston are possible, which may also be fixed, via which intermediate positions further functions can be triggered, whereby a further function, for example, can constitute a locking position of the working head in its working position.

In a further preferred embodiment, the first piston with a second piston received in a second cylinder is pivotably coupled. The second cylinder is preferably formed in the working head. The working head itself can form the cylinder. Due to the different pivot positions of the first piston different effects on the sliding in the second cylinder second piston can be achieved, so on, for example, a circuit of the second piston in the flow or return direction of the same. In addition, as an alternative or combinative to the running direction of the second piston, the force acting on the second piston and, moreover, the displacement speed of the second piston can also be specifically controlled via the pivoting position of the first piston relative to the working head.

The longitudinal axes of the two pistons, ie the first piston arranged in the hand tool and the second piston provided in the working head, can be arranged rectified one after the other in one embodiment of the subject invention, further also forming a common, both pistons centrally in the longitudinal direction or in Direction of movement passing through axis. In a preferred embodiment, the longitudinal axes of the two pistons run differently, that is to say enclose an angle of less than 180 ° with respect to one another, whereby these axes can certainly also be offset relative to one another in a plane directed transversely to the longitudinal axis extension. The aforementioned inclusion angle relates correspondingly to a projection of the piston longitudinal axes into a projection plane considered perpendicular to the longitudinal axis transverse plane. The included by the piston longitudinal axis angle may have a size of, for example 15 ° to 170 °, further example, from 45 ° to 135 °, more preferably, the first and the second cylinder T-shaped to each other. In this case, the included angle is not necessarily right-angled. This may well have a value other than 90 °, such as a value of 60 ° to 120 °, further for example a value of 75 ° to 105 °. In a further preferred embodiment of the subject invention, the compression between the first piston and the working head for fixing the pivoting position of the first piston is achieved by the same also the second piston moving hydraulic means. Accordingly, the second piston as well as the first piston is acted upon by the stored in the hand tool hydraulic fluid, further building a built-up by a provided in the hand tool hydraulic pressure. Accordingly, it requires for the operation of the second piston provided in the working head no separate means (hydraulic fluid). The operation of the working head is dependent on an assignment to the hydraulically actuated hand tool. For hydraulic actuation of the second piston in the working head of the first piston is formed by the hydraulic fluid permeable. Thus, the first piston flow paths, so on in particular inlet and outlet flow paths for the hydraulic fluid, which in a preferred embodiment, the channel-like manner, the first piston substantially aligned along the piston longitudinal axis. These flow paths are preferably used only for the flow of the working head or its piston acting hydraulic fluid.

To enable the pivotability of the first piston relative to the working head and the determination of the desired pivot position of the first piston within the first leading cylinder in the piston longitudinal direction is displaceable, this more preferably over a distance of a few millimeters, in particular over a distance of 0.1 mm 5mm, preferably 1mm to 3mm. Since the first piston serves primarily only as an actuating element to be fixed, its axial displaceability can be limited to a minimum dimension which makes it possible to set and release again. After overcoming this displacement path, the associated piston surface of the first piston frictionally engages a cylinder end surface formed by the working head. For this purpose, the first piston in a preferred embodiment with different formed large effective areas, wherein on the upstream side, a larger effective area is provided as on the downstream side of the first piston. The lower effective area on the downstream side is given in a further preferred embodiment by an area associated with the substantially pressure-free hydraulic return surface portion, which hydraulic return is achieved by a first piston passing through the flow path. This results in an effective area of the piston surface which can be brought into the operative position in relation to the cylinder bottom for the piston area to be pressurized. A sliding displacement of the first piston for fixing the same in the desired pivot position is also possible if on the downstream piston surface hydraulic fluid from a previous outflow from the second cylinder or from the working head is present, which hydraulic medium also in a blocking position of the downstream flow paths second cylinder or to the second piston can escape over the provided in the first piston hydraulic return substantially free of pressure. The displaceability of the thus designed differential piston in the Festsetzstellung is always given. At a preferred oil pressure of about 40 N / mm ^2, the first piston acts as a result of the proposed area ratios with a multiple of the value against the cylinder bottom, so for example with the 3- to 6-fold, further example. With 2 times the Value, that is about 80 N / mm ² . The metallically co-operating surfaces of the piston and cylinder base thus form an oil-tight transition.

In addition to the hydraulic return, a hydraulic flow for pressurizing the arranged in the working head second piston is also provided in the first piston at the same time. For this hydraulic flow an inflow opening is provided on the inflow side of the first piston for the entry of the same time also the first piston in the Festsetzstellung displaceable hydraulic fluid in the first piston. The inflow opening has a prestressed valve, which only when a predetermined by the bias voltage is exceeded Threshold the inlet opening for the passage of the hydraulic fluid releases. This threshold value is only reached after the first piston has shifted to the fixed setting position to the working head. Thus, a pressing of the first piston against the working head at the beginning of the pressure build-up on the inflow side of the first piston by form pressure generation by means of the valve designed as a pressure relief valve can be achieved. As a result, the first piston is moved to the beginning of the promotion with a force below the valve threshold, overcoming a seal friction within the first cylinder in the Festsetzstellung. In addition to the frictional pivotal determination between the first piston and the working head, a seal is thus achieved in the contact region of the downstream piston surface and the facing cylinder end surface. After exceeding the valve threshold value in the inflow opening and correspondingly after reaching the sealing position in the region of the interface between the first piston and the working head, the valve switches the hydraulic flow within the first piston free, for Hydraulikmittelbeaufschlagung arranged in the working head second piston. When the hydraulic pressure acting on the inflow side of the first piston is reduced, the valve arranged in the inflow opening first closes. In the course of further pressure reduction of the first piston acting as a differential piston is due to the finally acting on the downstream side overpressure shifted back from its sealing Festsetzstellung. Any contaminations, such as shavings or the like, located in the sealing region between the downstream piston surface of the first piston and the counter-sealing surface in the region of the cylinder end wall can be correspondingly flushed out by means of the hydraulic fluid.

The guided in the working head within the there formed second cylinder second piston is designed as a double-acting piston or differential piston and at least for movement in one direction at the same time in opposite directions with different effective surface sizes acted upon by the hydraulic fluid. This loading of the second piston can be done in both directions of movement of the second piston. In this regard, such loading is preferred only in one direction of movement, more preferably in the case of a forward displacement of the second piston from a rearward basic position. In this case, the pressurization of the differently effective piston surfaces is carried out with the same pressure, resulting in a difference force for movement of the second piston as a result of the different surface sizes. Further, the second piston is preferably pressurized only on one side for the return displacement, while the rear side is depressurized. Such a one-sided pressurization is also possible as an alternative with respect to the piston advancement. If necessary, the alternative pressure conditions can also be controlled via the various pivot positions. The different piston surfaces result in a preferred embodiment by arranging a piston rod on one of the two piston surfaces, which end of the piston rod carries a preferably over the cylinder projecting functional head. The latter is moved in accordance with the second piston linearly in the direction of the axial extension of the second piston. In the course of forward displacement of the functional head is expressed with the piston rod via the second piston from the second cylinder, this preferably by applying double-sided action of the second piston. By in this case in the ejection before the second piston pending hydraulic pressure can be achieved in a working position, in which the functional head, for example. Hanging down, a comparison with a horizontal extension of the functional head same extension speed. Also, any forces acting on the functional head, in particular tensile forces cause no possibly uncontrolled leading the second piston. Its forward displacement in the ejection direction of the functional head is damped. In the return direction, that is to say concretely with respect to the functional head in the withdrawal direction, the loading of the second piston preferably takes place only on one side, more preferably from the piston rod side piston surface and thus from the smaller piston surface, while the opposite, larger piston surface remains unpressurized. The hydraulic means located in this cylinder section is forced into the hydraulic supply via the larger piston surface for the return flow through the first piston. In a preferred embodiment, the piston surfaces of the second piston are dimensioned such that supply and return take place at the same speeds. This is preferably achieved by a reduced by 50% piston area on the piston rod side opposite the opposite piston surface. Correspondingly, equally large forces act on the second piston both in the forward and in the return direction. Alternatively, however, the piston surfaces may be in relation to one another in such a way that the tensile force acting in the return direction is greater or smaller than the ejection force acting in the advance direction.

At the end remote from the functional head, in a further development of the subject invention, the second piston has a projecting spring element for cooperation with the associated cylinder bottom. This is preferably an elastomeric part, which acts like a buffer. Accordingly, there is no hard impact against the associated cylinder bottom to complete the return movement. Alternatively, the spring element may for example also be a latch spring. In addition, the protruding spring element leaves in a retracted non-compressed starting position a clearance between the cylinder base and the facing piston surface, for the inflow of the hydraulic fluid. Furthermore, by arranging the spring element in the non-pressurized position of the second piston one, albeit minimal relative displacement of the second piston in the second cylinder allows, so on in particular over a path of several Tenths of a millimeter, for example, over 0.5mm to 2mm. The axial projection of the spring element corresponds, for example, about 1 to 5%, preferably about 2% of the axial Kolbenverlagerungswegs in the cylinder. Depending on the application of the working head, by enabling the relative displacement of the second piston and via its piston rod of the functional head, the attachment or removal of the working head can be facilitated by an admission part to be acted upon or to be entrained via the functional head.

For feeding the second piston arranged in the working head, an outlet opening and an outlet opening are formed in the end face of the first piston, wherein the outlet opening is connected to the piston inlet-side inlet opening via a channel passing through the first piston. The end surface side drain opening serves the hydraulic return from the second cylinder. Outlet opening and drain opening are separated from each other in terms of flow. In one embodiment, the outlet and drain openings may each have a circular cross-section corresponding to the downstream flow paths in the first piston on the end surface side of the first piston. It is further possible in this regard that at least one of the openings, so far preferably the drain opening is enlarged in area over the downstream flow path in cross-section, which resulting cross-sectional area of the drain opening may also be formed deviating from a circular shape. Thus, further, the drain opening may have a radially projecting from the flow channel connected to the drain port opening portion.

The drain opening associated with and formed in the first piston discharge line opens in a further preferred embodiment in one, in both directions - with respect to the extension direction of the piston longitudinal axis - sealed intermediate region, which intermediate region a between the piston outer surface and the cylinder inner surface in the region between two axially spaced-apart sealing regions adjusting annular space is assigned. This intermediate region is hydraulically separated from the hydraulic inlet region assigned to the inflow side of the first piston and is connected in fluid communication with a hydraulic storage container.

In the work head associated second cylinder, in any case, two hydraulic paths are formed in a development of the subject invention, which form the end face, that is, the downstream end face of the first piston associated openings. Correspondingly, these hydraulic passages as well as the inlet and outlet lines formed in the first piston open into the press-fitted region sealed to the working head in the setting position of the first piston. One of the second cylinder associated hydraulic paths is designed to act on the effective total cross section of the second piston, while the second hydraulic path is used to act on an annular space. This annular space is assigned to the areal smaller piston surface of the second piston, resulting from a cylinder space portion passing through, connected to the piston piston rod. The two piston surfaces of the second piston formed as a differential piston can be selectively actuated via the two hydraulic paths. At the same time serves at least one of the hydraulic paths as a drainage path for the hydraulic fluid.

The two openings of the hydraulic paths are arranged in the pivoting region of the outlet opening of the first piston, are accordingly both with the inflow side of the first piston, in particular switchable after displacement of the pressure relief valve in the open position, for selectively or combined action on the two piston surfaces of the second piston. Anyway, one of the openings of the hydraulic paths is hereby in Pivoting range of the drain opening of the first piston arranged, can accordingly form the return path for the hydraulic fluid to the storage container in dependence on the pivoting position of the first piston. Depending on the pivotal position of the first piston relative to the working head and thus also relative to the openings of the hydraulic paths, the latter are different from the outlet opening and the outlet opening of the first piston assignable, so as to achieve different effects on the second piston, so more preferred Flow and return movement of the piston.

In a further preferred embodiment of the subject invention, both openings of the hydraulic paths with respect to the outlet opening of the first piston and the pivoting region are arranged so that they can be simultaneously flowed through by hydraulic means. This results in the operation of the two-sided pressurization of the second piston designed as a differential piston. This configuration is preferably achieved in one of the pivoting end positions of the first piston. In the opposite pivot end position of the first piston, more preferably, only one of the openings of the hydraulic path is connected to the outlet opening of the first piston, while the opening of the other hydraulic path is associated with the discharge opening of the first piston. In addition, if necessary, latchable pivotal intermediate positions are possible, for example, a center position, in which although one of the hydraulic path openings of the outlet opening of the first piston is assigned, the opening of the second hydraulic path, however, neither the outlet nor the drain opening of the first piston is assigned blocked. In this position results in operation of the hand tool, that is, when building a hydraulic pressure no displacement of the second piston both in one direction and in the other direction. Further, a position may be provided, in which the hydraulic means, the second piston for advancement only on one side, namely on the piston rod acted on opposite piston surface. Correspondingly, the opening of the associated hydraulic path is assigned to the outlet opening of the first piston, while the opening of the hydraulic path associated with the piston area opposite the piston area engaged is connected to the outlet opening of the first piston. This results in a conventional hydraulic circuit circulation operation, with which very high forces can be achieved.

The generally free rotatable in the second cylinder about its longitudinal axis second piston is circumferentially aligned during retraction from a forward displacement position by means of a formed on the second cylinder catching recess. Thus, for example, a wedge-shaped outwardly widening groove is provided on the front side of the second cylinder, which serves for the circumferentially aligned reception of a radial projection arranged, for example, in the region of the functional head. This ensures that, in particular, the functional head is always aligned in the initial position, that is, in the retracted piston position in a positionally correct starting position.

The above-described features are also in terms of a hydraulic swing lock as such with passage of hydraulic fluid of importance. In this respect it does not depend on whether downstream a working head or even a (differential) piston is provided or whether it is a total of a hydraulic hand tool.

Fig. 1

in Ansicht ein erfindungsgemäßes Handwerkzeug mit einem Arbeitskopf;

Fig. 2

eine partiell geschnittene Vergrößerung des Kopfbereiches des Handwerkzeugs mit zugeordnetem Arbeitskopf;

Fig. 3

den Schnitt gemäß der Linie III - III in Fig. 1;

Fig. 4

den Querschnitt gemäß der Linie IV - IV in Fig. 3;

Fig. 5

den Schnitt gemäß der Linie V - V in Fig. 1;

Fig. 6

den Querschnitt gemäß der Linie VI - VI in Fig. 1;

Fig. 7

die Herausvergrößerung des mit VII in Fig. 6 bezeichneten Bereichs;

Fig. 8

den Schnitt gemäß der Linie VIII - VIII in Fig. 4;

Fig. 9

in einer perspektivischen Einzeldarstellung einen ersten Kolben des Handwerkzeugs mit Blick auf eine Abströmseite;

Fig. 10

eine Seitenansicht hierzu;

Fig. 11

den Längsschnitt gemäß der Linie XI - XI durch den ersten Kolben;

Fig. 12

den Arbeitskopf in einer perspektivischen Einzeldarstellung;

Fig. 13

den Kopfbereich des Handwerkzeuges mit zugeordnetem Arbeitskopf in geschnittener Darstellung, in Ansetzposition des Arbeitskopfes zugeordnet einem über den Arbeitskopf auszutreibenden Meißel aus einem Meißelhalter;

Fig. 14

den vergrößerten Schnitt gemäß der Linie XIV - XIV in Fig. 13;

Fig. 15

eine perspektivische partiell geschnittene Darstellung des Arbeitskopfes, die Grundstellung gemäß Fig. 13 betreffend;

Fig. 16

eine der Fig. 13 entsprechende Darstellung, jedoch die vorverlagerte Ausrückstellung betreffend;

Fig. 17

eine der Fig. 12 entsprechende Darstellung, jedoch die Arbeitsstellung gemäß Fig. 16 betreffend;

Fig. 18

eine der Fig. 15 entsprechende Darstellung, betreffend die Arbeitsstellung gemäß den Figuren 16 und 17;

Fig. 19

den Arbeitskopf in der Arbeitsposition gemäß Fig. 16 in perspektivischer Unteransicht;

Fig. 20

eine weitere der Fig. 13 entsprechende Darstellung, jedoch eine Zwischenstellung im Zuge der Rückverlagerung eines in dem Arbeitskopf beweglichen Kolbens;

Fig. 21

den vergrößerten Schnitt gemäß der Linie XXI - XXI in Fig. 20 und

Fig. 22

eine Querschnittsdarstellung gemäß Fig. 21, jedoch eine Zwischenstellung betreffend.

The invention is explained in more detail below with reference to the attached drawing, which represents only one exemplary embodiment. It shows:

Fig. 1

in view of an inventive hand tool with a working head;

Fig. 2

a partially cut enlargement of the head portion of the hand tool with associated working head;

Fig. 3

the section according to the line III - III in Fig. 1 ;

Fig. 4

the cross section according to the line IV - IV in Fig. 3 ;

Fig. 5

the section along the line V - V in Fig. 1 ;

Fig. 6

the cross section according to the line VI - VI in Fig. 1 ;

Fig. 7

the enlargement of the with VII in Fig. 6 designated area;

Fig. 8

the section according to the line VIII - VIII in Fig. 4 ;

Fig. 9

in a perspective detailed view of a first piston of the hand tool facing a downstream side;

Fig. 10

a side view of this;

Fig. 11

the longitudinal section along the line XI - XI through the first piston;

Fig. 12

the working head in a perspective detail view;

Fig. 13

the head region of the hand tool with associated working head in a sectional representation, in Ansetzposition of the working head assigned to be driven over the working head chisel from a chisel holder;

Fig. 14

the enlarged section according to the line XIV - XIV in Fig. 13 ;

Fig. 15

a perspective partially sectioned view of the working head, the basic position according to Fig. 13 concerning;

Fig. 16

one of the Fig. 13 Corresponding presentation, however, concerning the forward-shifted release;

Fig. 17

one of the Fig. 12 corresponding representation, but the employment position according to Fig. 16 concerning;

Fig. 18

one of the Fig. 15 corresponding representation, concerning the employment status in accordance with Figures 16 and 17 ;

Fig. 19

the working head in the working position according to Fig. 16 in perspective bottom view;

Fig. 20

another one Fig. 13 corresponding representation, but an intermediate position in the course of the return displacement of a movable piston in the working head;

Fig. 21

the enlarged section according to the line XXI - XXI in Fig. 20 and

Fig. 22

a cross-sectional view according to Fig. 21 , but with an intermediate position.

Shown and described is first with reference to FIG. 1 a suitable for single-handed operation electro-hydraulic (trunk) hand tool 1 for actuating an arranged working head 2. The latter is used for expelling or drawing a chisel 3 from or into a chisel holder. 4 As can be seen from the illustrations, the hand tool 1 is designed substantially elongate rod-shaped, which supports the one-handed operation of the tool. This rod-shaped configuration is achieved in that the individual assemblies are positioned in the housing 5 in axial succession arrangement and further aligned substantially in alignment with a longitudinal axis y of a linearly displaceable in the hand tool 1 first piston 6. In the area of the electric motor, not shown, the housing 5 forms a grip area 7, the housing diameter being selected to be ergonomically adapted in this grip area 7.

The electric motor is fed by a battery 8 which can be plugged in the axial direction of the electric motor. The battery 8 can be plugged into and latched into a corresponding housing receptacle. The device can also be formed directly with power plug operation, or be provided in addition to the accumulator 8 with a power plug.

By means of the electric motor, the first piston 6 is moved in a known manner in the hand tool 1 via an oil pressure increase, this along its longitudinal axis y.

In order to implement the oil pressure-loaded linear displacement of the first piston 6 from the rotational movement of the electric motor, a transmission is arranged between the electric motor and a pump. By means of the transmission, the implementation of the rotational movement is achieved by the electric motor in an oscillating pumping movement of a pump tappet 9. This reciprocating pumping movement takes place in the axial direction of the motor shaft and correspondingly further in the axial direction of the first piston 6.

With regard to the configuration and operation of the transmission and the pump is with regard to further details on the above-mentioned DE 10216213 A1 directed.

With the oscillating movement of the pump plunger 9, the first piston 6 is oil pressure-applied via a valve arrangement, not shown. The first piston 6 is in this case in a first cylinder 10 of a tool-side head 11 a. This head 11 is provided with an external thread for cooperation with a corresponding internal thread of the attachable working head 2.

Furthermore, a return valve 12 is provided in juxtaposition, that is offset parallel to the pump plunger 9, which at one end is conductively connected to the pressure chamber 13 in front of the first piston 6. This return valve 12 opens automatically when a predefined pressure in the pressure chamber 13 is exceeded and opens a path to the pump or the pump tappet 9 and the return valve 12 annularly surrounding the hydraulic storage container 14.

The opening of the check valve 12 causes a resetting of the first piston 6 in the unloaded basic position via a on the pressure chamber 13 opposite piston surface of the first piston 6 acting force.

A to the formation of the line connection of return valve 12 and pressure chamber 13 manufacturing technology necessary, as aligned transversely to the axis y bore 68 is closed to separate the pressure chamber 13 from the storage container 14 by a screw-69.

To operate the hand tool 1 and thus to switch on the electric motor, a pivotable actuating switch 15 is provided in the grip area 7. The substantially circular cylindrical designed working head 2 forms a second cylinder 16, in which a second piston 17 is guided linearly. The longitudinal axis x of the second piston 17 is aligned at right angles to the longitudinal axis y of the first piston 6, an extension of this longitudinal axis y cutting.

Mantelwandungsaußenseitig is formed on the second cylinder 16 a circular cross-section, aligned in the state of assignment to the hand tool 1 coaxial with the longitudinal axis y of the first piston 6 aligned flange 18. This is the inside of the wall for fixing the working head 2 on the hand tool 1 in the region of a radial extension of the interior with the, provided with the external thread of the first cylinder 10 meshing internal thread. The axially adjoining the internal thread, rooted in the cylinder wall flange portion forms on the inside wall a portion of the first cylinder 10, correspondingly forms an extension thereof.

The first piston 6 guided in the first cylinder 10 initially has an outer diameter reduced in relation to the inner diameter of the cylinder and is further designed substantially as a solid body, with a length considered in the axial direction which is approximately 0.9 to 0.98 times further about 0.97 times the considered in the same direction length of the first cylinder 10 including the cylinder 10 further forming this flange portion corresponds. This results in an exemplary piston length of about 70 mm, a possible displacement of the first piston 6 in the first cylinder 10 of about 2mm.

Distributed over the length of the first piston 6 is provided with radially expanded portions 19, 20, 21, whose outer diameter are adapted to the inner diameter embedded in these extended sections 19 to 21 of the first piston 6 carries in correspondingly positioned circumferential annular grooves 22 ring seals 23, which occur radially outwardly sealing against the cylinder wall.

The extended portion 19 is formed in the pressure chamber 13 facing the end portion of the first piston 6. At this opposite end of the second extended portion 20 is formed, for cooperation with the, the enlarged cylinder-forming flange portion of the working head 2. Between the end-side sections 19 and 20, the further extended portion 21 is positioned, with an axial distance to the pressure chamber side portion 19th , which corresponds approximately twice the distance to the frontal section 20. This results in between the sections 19 and 21 or 20 and 21, the first piston 6 comprising annular spaces 24 and 25, wherein the created between the pressure chamber side portion 19 and the central extended portion 21 annular space 24 via a transverse to the axis y radially to externally aligned bore 26 communicates with the storage container 14.

The first piston 6 is designed for the flow of hydraulic fluid. For this purpose, this first has a substantially parallel to the piston axis y extending inflow 27, which extends over the entire length of the piston 6 and thus opens both on the inflow side A and on the outflow side B of the first piston 6 and there corresponding to an inflow 28 and an outflow opening 29 ausformt, wherein further in the immediate region of the outflow opening 29 of the inflow passage 27 has a radial offset to the outside. The outflow opening 29 is formed in the pressure chamber 13 facing away from the end surface 30 as a circular opening.

The inflow opening 28 of the inflow channel 27 is formed in an axial extension 32 screwed into the inflow channel 27 from the end face 31 of the piston 6 facing the pressure chamber 13. This projects according to the arrangement of the inflow 27 in an eccentric assignment beyond the end face 31, wherein further the axial extension 32 rests positively in an associated axial slot 33 in the pressure chamber 13. As a result, a backup of the first piston 6 is given against rotation about its longitudinal axis y with further enabled linear displacement along the longitudinal axis y.

The inflow opening 28 is closed in the unloaded position by a prestressed valve 34. In the illustrated embodiment, this is a pressure controllable ball valve, with a ball 35 which is aligned within the axial extension 32 parallel to the longitudinal axis y against a rearwardly acting against the ball 35 compression spring 36 from its sealing seat position against the inflow opening 2 by pressurizing the inflow opening 28 is displaced.

Further, in the first piston 6 and a drain passage 37 (see FIG. 11 ) intended. This also extends parallel to the piston longitudinal axis y, starting from the pressure chamber 13 opposite end face 30 of the piston 6 about half the extension length of the piston 6 and goes here in a radially outwardly directed transverse bore 38. This opens into the between the extended sections 19 and 21 of the piston 6 in the axial direction limited and sealed annular space 24th

At the end, the discharge channel 37 forms a discharge opening 39 that is initially circular in plan, and that merges further in the area of the end face 30 into an extension section 40 extending radially outward. This is formed out of the end face 30 recess-like and extends to the end edge edge edge such that a relative to the longitudinal axis y, the inflow opening 28 opening in the end face 30 traverses the extension section 40 in the center thereof in its extension, this continues with an adjacent allocation of the extension section 40 and inflow opening 28, including an angle of approximately 30 °.

The plan, aligned transversely to the piston axis y end face 30 is optionally spaced with the order of the displacement of the piston 6 a plane even directed, also flat cylinder head surface 41 foot side of the working head flange 18 opposite. In this cylinder head surface 41 two associated with the formed in the working head 2 second cylinder 16 associated hydraulic paths 42, 43. Their openings 44 and 45 are arranged on an axis y relating to the circular line, which in a projection on the opposite end face 30 of the first piston 6 intersects the inflow opening 28 and the extension section 40. Next, the openings 44 and 45 are arranged offset by an angle of about 20 ° in the circular line direction to each other.

The second piston 17, which is displaceable linearly along the longitudinal axis x in the second cylinder 16, is designed as a differential cam. Thus, first of all, this piston 17 has a first piston surface 47, which faces a cylinder bottom 46 and corresponds in terms of area substantially equal to the cross-sectional area of the cylinder interior.

This piston surface 47 is opposite to the piston 17 centrally coaxially to the axis x over the opposite end of the cylinder 16 extending beyond piston rod 48 is formed, which is diametrically selected so that radially outwardly, the piston rod 48 on the opposite piston surface 47 Side of the piston 17 results in an annular piston surface 49 which corresponds in terms of area in the illustrated embodiment 0.5 times the opposite piston surface 47.

The outside of the jacket, the second piston 17 is provided with a piston ring seal 50, which cooperates sealingly with the inner wall of the second cylinder 16.

The effective cylinder space 16 has an extension length which corresponds approximately to 4 times the cylinder diameter.

The piston rod 48 passes through in the region of the cylinder bottom 46 facing away from the end of the cylinder 16 centrally a guide insert 51. The latter is the cylinder end side wall inside screwed to the cylinder wall. Facing the cylinder chamber carries the guide insert 51 radially outward a circumferential seal 52 for sealing the cylinder chamber to the outside.

Radially inside in the interaction area with the piston rod 48, the guide insert 51 carries two further gaskets arranged at a distance from one another in the axial direction, an axially inner seal facing the cylinder chamber being a ring seal 53 and an axially outer seal in the form of a stripping element 54 ,

The in the basic position, that is, in the area of the cylinder bottom 56 abstützendem second piston 17 axially beyond the cylinder 16 and beyond the guide insert 51 beyond free end of the piston rod 48 rotatably supports a functional head 55. This is used in the illustrated embodiment for gripping a free end of the chisel shaft 56 of the chisel 3 held in the chisel holder 4.

The functional head 55 is configured claw-like for mounting the free end of the chisel shaft 56, so as to engage in a shaft end-side annular groove of the chisel shaft 56.

The functional head 55 is in a basic tool position according to the FIGS. 13 to 15 taken in a functional head 55 at least partially comprehensive support portion 57. This is the same material, integrally formed from the cylinder wall pot-like shape.

Parallel to the flange 18, which is further associated with the cylinder bottom 46 of the second cylinder facing away from the cylinder end, in the support portion 57 in the linear movement space of the functional head 55 radially engaging cam 58 is attached. This is formed in the illustrated embodiment by a screw head of a fastened in a shell portion of the support portion 57 screw. The screw head or the cam 58 cooperates with a wedge-shaped opening axially aligned groove 59 of the functional head 55. This groove 59 is open radially outward. By means of this configuration, by co-operation of the cam 58 and the groove 59 in a return displacement of the functional head 55 in the basic position, a circumferential orientation of the functional head 55 and over this the entire otherwise non-rotatable piston assembly in the working head 2 achievable, so the functional head 55 from a always operate in the same basic position. Due to the widening groove 59 is a self-centering in cooperation with the cam 58 achievable.

The second piston 17 receives centrally on the opposite side of the piston rod 48, a spring element 60. In the illustrated exemplary embodiment, this is an elastomer part, which is held in a central bore 61 opening into the piston surface 47 and projects beyond the associated piston surface 47 with an axial dimension of approximately 1 mm to 2 mm.

About the free spring element end face, the second piston 17 is supported in an unloaded basic position while leaving a free end portion of the spring element 60 surrounding annular space on the associated cylinder base 46 from.

The in the first piston 6 associated cylinder head surface 41 opening into the opening 45 hydraulic path 43 extends parallel to the piston axis y stitch-like straight to the mouth in which between the second piston 17 and the guide insert 51 and the piston rod 48 penetrated annular space 62, which is formed by the axially at both ends provided seal in the region of the second piston 17 and in the region of the guide insert 51 as a pressure chamber.

The second opening into the opening 44 hydraulic passage 42 passes through parallel to the axis of the second piston 17, the cylinder wall to expire end in the region of the cylinder bottom 46 via a radially inwardly facing transverse channel 63 in the pressure chamber 64 formed between the cylinder bottom 46 and the second piston 17 ,

The entire working head 2 and thus also guided in this piston 17 and the cylinder 26 are pivotally supported relative to the hand tool 1 and thus relative to the rotatably guided in the hand tool 1 first piston 6 about the piston axis y to the head 11, this in the illustrated embodiment over a limited pivot angle of about 17 ° to 18 °. Due to this pivotability, a relative pivotal displacement of the hydraulic-path-side openings 44 and 45 to the piston-side outflow opening 29 and the discharge opening 39 can also be achieved.

The angle-limited pivotal displacement is achieved by a flange 18 radially penetrating screw 65, which projects radially inwardly beyond the Flanschinnenwandung and there dips into a recessed recess 66 of the head wall. This Ausnehmungsfreisschnitt 66 has a width considered in the circumferential direction of the head 11, which allows in cooperation with the screw end the relative pivoting of the flange 18 to the head 11 by the prescribed angular amount.

• Durch stete Druckerhöhung in dem Druckraum 13 vor dem ersten Kolben 6 wird zunächst der erste Kolben 6 linear in dem ersten Zylinder 10 vorverlagert, dies um das Überlängemaß von etwa 2mm des Zylinders 10. Entsprechend wird die Stirnfläche 30 des ersten Kolbens 6 gegen die zugewandte Zylinderkopffläche 41 gepresst, womit einerseits die eingestellte Verschwenkstellung von Handwerkzeug 1 und Arbeitskopf 2 zueinander festgesetzt wird, andererseits weiter die Abdichtung zwischen erstem Kolben 6 und Zylinderkopffläche 41 erreicht wird. Die zunächst durchgeführte Vorverlagerung des ersten Kolbens 6 wird erreicht durch die Wirkung als Differentialkolben. Die dem Druckraum 13 zugewandte Kolben-Stirnfläche 31 weist ein größeres wirksames Flächenmaß auf als die dieser abgewandte Stirnfläche 30, welche insbesondere um den Flächenanteil der Ablauföffnung 39 und des Erweiterungsabschnittes 40 flächenmäßig reduziert ist. Etwaiges sich noch zwischen Stirnfläche 30 und Zylinderkopffläche 41 befindliches Hydraulikmittel wird über die Ablauföffnung 39 und den Ablaufkanal 37 in das Vorratsbehältnis 14 verdrängt.

The result is the following mode of action:

• By constant pressure increase in the pressure chamber 13 before the first piston 6, the first piston 6 is first linearly displaced in the first cylinder 10, this about the Überlängemaß of about 2mm of the cylinder 10. Accordingly, the end face 30 of the first piston 6 against the facing cylinder head surface Pressed 41, whereby on the one hand the set pivoting position of the hand tool 1 and working head 2 is fixed to each other, on the other hand, the seal between the first piston 6 and cylinder head surface 41 is achieved. The first forward displacement of the first piston 6 is achieved by the action as a differential piston. The pressure chamber 13 facing the piston end face 31 has a larger effective area measure than that facing away from the end face 30, which is reduced in area by the surface portion of the drain opening 39 and the extension portion 40 in particular. Any remaining between end face 30 and cylinder head surface 41 hydraulic fluid is displaced via the drain port 39 and the drain passage 37 into the storage container 14.

By a further increase in pressure on the piston surface assigned to the end face 31, a threshold value for opening the inlet opening-side valve 34 is exceeded. The same hydraulic means, which causes the advancement of the first piston 6, flows after opening the valve 34 via the inflow passage 37 through the first piston 6 in the direction of the end face 30 to there over Covering the outflow opening 29 brought openings 44 and / or 45 in the second cylinder 16 to arrive.

For forward displacement of the second piston 17 in the second cylinder 16, that is in the illustrated embodiment for expressing the bit 3 from the bit holder 4 and corresponding axial Auswärtsverlagerung the functional head 55 bearing piston rod 48, a pivot position between the tool 1 and working head 2 is set, in which both openings 44 and 45 of the two working-head-side hydraulic passages 42 and 43 are in fluid communication with the outflow opening 29 of the inlet formed in the first piston 6 inlet passage 27. According to this embodiment is on the annular space 62 and the pressure chamber 64 on both sides of the second piston 17, a pressure constructed, which acts with respect to the second piston 17 in opposite directions. As a result of the differently effective surface areas of the piston surface 47 and the piston surface 49, a uniform, damped forward displacement of the piston 17, piston rod 48 and the tool head 55 of the bit 3 from the bit holder 4 is achieved. Furthermore, due to the only slightly required disengagement forces, a piston rod 48 of adequate size with regard to the cross-sectional area is achieved.

In the course of this Ausdrückvorganges the working head 2 is supported with its rear, the cylinder bottom 46 associated outer end face 67 on an edge of the pocket for receiving the working head 2 trained chisel holder 4 (see. FIG. 16 ).

For the return displacement of the piston rod 48, for example, for re-inserting the bit 3 in the bit holder 4, the hand tool 1 is pivotally displaced about the axis y relative to the working head 2 such that thereafter the opening 45 of the hydraulic path 43 in register with the discharge opening 29 of the piston-side inflow passage 27 and the opening 44 of the hydraulic path 42 overlap with the extension portion 40 of the drain port 39. The hydraulic fluid acts under pressure correspondingly in the annular space 62 on the smaller piston surface 49 of the second piston 17, while the rear, larger piston surface 47 can escape pressure-free. The hydraulic means located in the associated pressure space 64 is forced back into the storage container 14 via the hydraulic path 42, the opening 44 and further via the extension section 40 and the discharge opening 39.

By the selected piston area ratios and the two-sided pressurization of the piston surfaces 47 and 49 in the advancement and the only one-sided loading of the smaller piston surface in the return displacement of the piston rod 48 moves this both in Vorverlagerungsrichtung and in Rückverlagerungsrichtung at the same speeds.

During the insertion displacement of the piston rod 48, the working head 2 is supported on the face side with the support section 57 on the now associated flank of the bit holder 4 (cf. FIG. 20 ).

At the end of the return displacement of the piston rod 48, the second piston with its projecting spring element 60 strikes against the cylinder bottom 46, which initially causes a compression of the spring element 60 upon further pressurization of the smaller piston surface 49. When the hand tool 1 is switched off, for example triggered by the automatic return valve 12, which opens as a function of a pressure threshold value, the pressure acting on the smaller piston surface 49 is reduced, which triggers the subsequent decompression of the spring element 60. This results in a minimal axial displacement of the second piston 17 and above this the piston rod 48 by the Dekomprimierungsmaß of the spring element 60 of about 2mm result. By the relative displacement between the over the functional head 55 on the drill collar 56 supporting piston rod 48 and second cylinder 16 takes place, albeit a slight spacing of the support portion 57 to the support surface.

The two above-described pivot positions between hand tool 1 and working head 2 correspond to the Schwenkendstellungen. As further from the representation in FIG. 22 can be seen in the course of the pivoting change an intermediate pivoting position in which the opening 45 of the connected to the annulus 62 hydraulic path 43 is in communication with the inflow 27 of the first piston 6 and the opening 44 of the pressure chamber 64 extending hydraulic path 42 in lighter , but functionally sufficient coverage is to the extension portion 40. In this pivotal intermediate position, the second piston 17 in the working head 2 is depressurized.

When the automatic return valve 12 responds, the pressure limiting valve 34 in the first piston 6 is optionally loaded in the closing direction by the hydraulic fluid flowing back. The valve 34 may be formed in a development that this opens in the closing direction even at a low pressure, thus representing a corresponding acting in both directions pressure relief valve. Alternatively, an additional conventional check valve may be arranged in the first piston 6, which allows the return flow of the hydraulic medium.

The invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the longitudinal axes (x, y) of the two pistons (6, 17) run differently.

The subject of the invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the first and second cylinders (10, 16) are T-shaped with respect to each other.

The invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the compression between the first piston (6) and the working head (2) by the same and the second piston (17) moving hydraulic means is reached.

The invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which an inflow opening (28) of the first piston (6) has a prestressed valve (34).

The subject matter of the invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the second piston (17) has at its end a functional head (55) protruding beyond the cylinder (16).

The subject matter of the invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the second piston (17) has a protruding spring element (60) at its end remote from the functional head (55). has, for cooperation with the associated cylinder bottom (46).

The subject of the invention, which may be meaningful both alone and in combination with one or more of the further features, is also a Hand tool in which the intermediate region is fluidly connected to a hydraulic storage container (14).

The invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which both openings (44, 45) with respect to the outflow opening of the first piston (6) and its pivoting region are arranged so that they are simultaneously flowed through by hydraulic fluid.

The subject matter of the invention, which may be meaningful both alone and in combination with one or more of the further features, is also a hand tool in which the second piston (17) is circumferentially aligned during retraction by means of a catch recess formed on the second cylinder (16) is.

All disclosed features are essential to the invention. The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application.

LIST OF REFERENCE NUMBERS

1

hand tool

2

working head

3

chisel

4

toolholders

5

casing

6

first piston

7

grip area

8th

accumulator

9

pump plunger

10

first cylinder

11

head

12

Return valve

13

pressure chamber

14

storage container

15

actuating switch

16

second cylinder

17

second piston

18

flange

19

extended section

20

extended section

21

extended section

22

annular groove

23

ring seals

24

annulus

25

annulus

26

drilling

27

inflow

28

inflow

29

outflow

30

face

31

face

32

axial extension

33

Axialschlitzführung

34

Valve

35

Bullet

36

compression spring

37

drain channel

38

cross hole

39

drain hole

40

Enhancements section

41

Cylinder head surface

42

hydraulic path

43

hydraulic path

44

opening

45

opening

46

cylinder base

47

piston area

48

piston rod

49

piston area

50

Piston ring seal

51

Leadership commitment

52

ring seal

53

ring seal

54

scraper

55

function head

56

drill collar

57

support section

58

cam

59

groove

60

spring element

61

drilling

62

annulus

63

Querkanal

64

pressure chamber

65

screw

66

Ausnehmungsfreischnitt

67

Outer-end face

68

drilling

69

screw plug

A

inflow

B

outflow

x

Longitudinal axis second piston

y

Longitudinal axis of the first piston

Claims (15)

Preferably hydraulically actuated hand tool (1) with a working head (2) and a contrast remaining trunk device, wherein in the trunk device for driving the working head (2) drive elements are provided, for example, a hydraulic pump and a hydraulic reservoir, wherein further by a switching movement, a force movement of or a plurality of working parts of the working head (2) can be triggered and the working head (2) is pivotally connected to the hull device in a rotary connection area, characterized in that by pivoting the trunk device relative to the working head (2) to one in the rotary connection area the working head to the fuselage device given rotation axis switching with respect to the force movement of the working part is feasible. Hand tool according to claim 1 or in particular according thereto, characterized in that a pivoting position between the working head (2) and the trunk device can be fixed. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the trunk device comprises a first piston (6) which pivots in the course of the switching movement about its longitudinal axis (y) extending in the direction of movement. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the first piston (6) with the working head (2) can be coupled. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the first Piston (6) relative to the working head (2) is pivotable. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the pivoting between the working head (2) and the trunk device or the working head (2) and the first piston (6) is angularly limited. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that a pivoting position between the first piston (6) and the working head (2) by direct contact between the first piston (6) and the working head (2) can be fixed. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the first piston (6) with a second, in a second cylinder (16) received piston (17) is pivotally coupled. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the first piston (6) can be flowed through by the hydraulic means. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the first piston (6) on the upstream side (A) has a larger effective area than on the downstream side (B), wherein the smaller effective area on the downstream side ( B) is given by an associated with the substantially pressure-free hydraulic return surface area ratio. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the second piston (17) is designed as a double-acting piston and in any case can be acted upon for movement in one direction at the same time in opposite directions with different effective surface areas with the hydraulic medium. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that in the end face (30) of the first piston (6) an outflow opening (29) and a drain opening (39) are formed. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that one of the drain opening (39) associated in the first piston (6) formed drain line (37) in a, sealed in both directions intermediate region of the first piston (6) empties. Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that in the second cylinder (16) at least two of the end face (30) of the first piston (6) associated, forming openings (44, 45) hydraulic paths (42, 43 ) are formed, one of which is designed to act on the effective total cross section of the second piston (17) and the second for acting on an annular space (62). Hand tool according to one or more of the preceding claims or in particular according thereto, characterized in that the two openings (44, 45) of the hydraulic paths (42, 43) in the pivoting region of the outflow opening (29) are arranged and that in any case one of the openings (44, 45) in the pivoting region of the drain opening (39) of the first piston (6) is arranged.

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