Abstract:
In a hydraulic valve ( 10 ), the housing ( 34 ) is composed of plate-shaped segments ( 36  to  46 ). Sections of longitudinal channels ( 96, 97 ) are formed by recesses having cross-section with a closed edge which overlap or are flush with corresponding channel sections of the adjacent channels. Radial channels, which are in communication with a supply connection ( 11, 12 ) or a consumer connection ( 13, 14 ) are formed by radial indentations ( 86  to  89 ) of central openings ( 75, 77, 79  and  81 ) of housing segments ( 38, 40, 42  and  44 ). Grooves ( 91, 92, 93  and  93 ) which widen the cross-section of the central housing channel ( 71 ) within which the valve piston ( 19 ) can slide in a pressure tight manner in the axial direction and/or rotation outwards are formed by recesses ( 75, 77, 79  and  81 ) of the housing segments ( 38, 40, 42  and  44 ) having a larger diameter and which positively overlap the central channel ( 71 ) in cross-section. The segment plate ( 36  to  46 ) are positively and form-fittingly joined and/or materially joined into a dimensionally stable package into which welding material is laid into closed compartments which are formed by recesses ( 121  to  134, 126 ) of the segment plates ( 37  to  45 ) interconnected into groups and which extend over the whole series of joints of the segment plates ( 36  to  46 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a hydraulic valve, in which by relative movement between a piston and a housing, which in spatially defined configuration has supply and user connections, via which pressure medium can flow from a pressure supply aggregate to a user and from this back to a supply container of the pressure supply aggregate, various defined flow paths can be selected, which are associated with various defined functions of the user, for example, forward movement, resting or backwards movement of the piston of a hydraulic cylinder, wherein in various functional positions of the hydraulic valve various respectively defined combinations of flow paths are opened or closed off or subcombinations of such paths are opened and other sub-combinations closed off, wherein segments of such flow paths are formed by grooves in the housing and/or the piston as well as housing and/or piston channels, which communicatingly connect such path sections with each other or with supply or as the case may be user connections. 
     DESCRIPTION OF THE RELATED ART 
     n-way/m-position-valves of this type are generally known and are offered as either switch valves which are switchable between discrete functional positions or as proportional valves which, with increasing displacement of their piston out of a base position, increasing open up a flow-path cross-section, and are offered by hydraulic component suppliers in the most compatible, that is, corresponding, variations of known configurations of their supply, user and/or control connections, so that a unit manufactured by one manufacturer is exchangeable with a corresponding unit of another manufacturer. 
     The housing of such valves is as a rule produced of aluminum or steel cast parts, in which at least the basic shape as defined by a central through-going housing channel, which receives the valve piston, the basic shape of this channel including widening grooves, the flow in such grooves joining lengthwise or transverse channels, which are in communicating connection with connection openings of the valve housing, as well as the flow or path of channels which internally connect housing grooves with each other without being directly in communicating connection with a supply or user connection of the valve housing, is predetermined by the shape of a cast core, which is introduced into the outer cast shape, which in turn determines the shape of the outer surfaces of the housing, wherein this cast core after the casting of the valve housing can fall apart and the core material, fine grained sand, must be quantitatively removed in a simple manner from the cast body. 
     This embodiment of the valve housing as cast part is completely practical in the view point of a highest possible fluid-tightness (avoidance of the requirement for an external plugging internally with each other communicating transverse and longitudinal boreholes of the housing), the mechanical load carrying capacity and also the somewhat rational manufacturing process; however it is also associated with a variety of serious disadvantages: 
     Even when it is so organized, that a rational manufacturing process of numerous housings is possible in a single casting process, the production of the cast core is associated with a high technical demands, which is expensive. 
     The shapes of the housing hollow spaces in the housing, which during casting are filled with sand kernels, must be so constructed or shaped, that the kernel material after the casting is reliably removable after casting. Herein it is required, for reasons of the sufficient stability of the casting kernels, that minimum cross-sections of cast core batches are required, which for example connect housing internal grooves of the central housing channel with each other. 
     Since a follow-up processing of the central channel of the cast housing, for example with conventional penetrating tools, is unavoidable in order to achieve sufficiently precise housing side control edges, through which by positive or negative overlapping with piston side control edges the various functional positions of the valve are achievable, the axial separation of such housing side control edges must as a rule be selected to be substantially greater than would be necessary from flow technical reasons. The manufacturing length of the known valves is thus for reasons of product finishing as a rule significantly greater than would be required for physical reasons. Correspondingly, the axial dimensions of the pistons in linear displacement valves must be greater, which also results in a corresponding enlargement of their mass. 
     SUMMARY OF THE INVENTION 
     The task of the invention is thus, to improve a hydraulic valve of the above-described type such that it can be manufactured, without detracting from the functional characteristics and the precision of the arrangement and construction of its control edges as well as with a good sealing of the housing, with substantially less expenditure and also can be produced with significantly smaller spatial dimensions. 
     According thereto the housing of the valve is assembled from planar-parallel, plate-shaped segment-sheets, in which segments of longitudinal channels of the housing are formed by clearances having a cross-section with a closed edge, which overlap or are aligned with corresponding channel sections of adjacent channels; radial channels or segments of such channels, which are connected in communication with a supply connection or a user connection, are formed by radial bulges of central openings of the housing segments, which are oriented or provided along a common central longitudinal axis; the cross-section of a housing channel defined by the edges of a central opening, within which the valve piston in pressure type manner is axially displaceable and/or rotationally turnable, radial widening grooves are formed by clearances of larger diameter of the housing segment which positively overlap the central channel in cross-section; the segment plates are materially joined by brazing, wherein during the brazing process they are positively and form-fittingly joined or in certain cases materially joined into a dimensionally stable package; a brazing material required for the mechanically secure material joining of the segment plates is introduced into enclosed compartments, which are formed by group-wise interconnecting clearances of the segment plates and which extend over the entire series of the segment plates. 
     By this design of the inventive valve technical advantages are achieved including at least the following: The clearances or through-holes of the individual segment sheets can be produced on NC- or CNC-controlled bore and/or punching or stamping machines with high precision, wherein also channel paths can be produced in simple manner, which in casting technology practically are not realizable or are realizable only at great expense. 
     Since axial groove widths are determined in simple manner by the thickness of the segment sheets, which by the edge of their clearances determines the flow path of the groove base, such groove widths can in simple manner be limited to the physically required minimal value and for example in the case of magnet controlled linear displacement valves, can be tailored to the lift or stroke of the available control magnets, whereby shortenings of the axial construction length of the valve housing can be achieved which correspond to 30% of the construction length of a conventional valve housing. The mass of the piston is also reduced by a corresponding percentage value. 
     The thin brazed layers, which are produced as a result of the capillary action between the sheet metal plate segments, produce an absolute tight and secured connection of the housing segments with each other. The sealing and mechanical load capacity of the housing is equivalent to that of a conventional cast housing. It can further be said that the casting flaws which are statistically unavoidable with cast housings, for example contraction cavities, cannot occur, so t hat the valve housings produced according to the invention are produced with a statically lower reject quota. As a result of providing the brazing material in closed compartments, there is also made possible a very precise measurement of the brazing amount for the respective segment plate surfaces to be brazed to each other. 
     It can also be advantageous when the receiving space for the wire shaped brazing material is designed as a confluent channel, which, running meanderingly or spiral shaped, extends through the housing and in the finished valve is usable as a flow-through *channel for cooling medium or gas. Such a channel can be produced during the construction process intended for producing the housing without difficulty, such that the cooling fluid flows through the thermally particularly stressed z ones of the valve housing and that in accordance therewith a effective removal of heat is possible. 
     By the possibility of producing enclosed hollow spaces, which in casting technology is not possible, it is also possible to realize a light construction manner with substantial weight savings, without having to sacrifice stability. Further there exits the possibility, to connect relatively large volume spaces with small channels, in order for example to achieve the effect of a buffer. 
     A follow-up processing of the housing is essentially necessary only in the manner, that the respective circular spaced, central openings of the housing segment, in which the valve piston is mounted pressure-tight rotatably or axially slidable, are to be brought into exact corresponding diameter and exact aligned arrangement with each other. Given as preconditions the manufacturing precision which is conventional for NC- and CNC-controlled processing machines for the individual plate segments of the housing as well as their positionally correct form-fixing prior to the brazing process, which is achievable without more by simple alignment aids, the follow up processing of the housing can as a rule be limited to the honing processing of the central clearance of the segment plates, which is not associated with a seam forming of the control edges, which from the manufacturing technical prospective is likewise of substantial advantage. The inventive valve is thus overall substantially more economical to produce than the valve with a housing formed by casting technology. 
     For the arrangement of reception channels for brazing material, which extend over the entire length between the end plates of the segment package, or only over segments thereof, however are in positive overlap with each other, at least in all cases are interrupted by only one segment from each other, it is in each case advantageous, when such receiver channels are arranged axially symmetric with respect to the central longitudinal axis of the central housing channel, that is, in areas, which correspond respectively approximately to the radial separation from the at the furthest removed surface areas which must be joined by brazing. 
     For positionally correct prefixing of the segment plates to each other as required prior to the brazing process, fixing posts can be used which extend between the end segments of the segment packages and transition through clearances of the plate shaped segments aligned with each other and in a form of post-like pull anchors secured to one or the other of the end segments, which is riveted on the other side of the package with the there situated end plate, but also “loose” fixing posts, which are riveted respectively with both end plates of the segment package. In each case it is advantageous when the diameter of the fixing posts correspond to the diameter of the alignment clearances of the housing segments, so that the fixing posts are also useable for the mutual or inter-changeable centering adjustment of the segment plates. 
     The positionally correct prefixing of the segment plates for the brazing process is also possible in the manner, that the segment plate package is form fittingly held together by caulking anchoring bodies laid into edge opening recesses of the edges of the plate shaped segments aligned with each other, wherein the edge openings, with each other aligned recesses preferably form a longitudinal groove with a towards outwards narrowing trapezoid cross-sectional shaped interstitial space, and the anchoring bodies are formed as flat or shallow arched posts or slats, which by pressing into the groove achieve the form locking anchoring of the plate shaped segments. 
     A suitable form-stable fixing of the segment package of the housing can also be thereby achieved, when the segment plates are materially joined or bonded with each other by small welding beads, which in suitable, preferably axially symmetric arrangement are applied over the plate joints. It is a precondition for this, that the segment plates during the welding or brazing can be held to each other in their characteristic configuration necessary for the finished housing. 
     A positionally correct fixing of the plate shape segments to each other, which is at the same time automatic, is also thereby achievable, in that segment plates arranged adjacent each other are provided with co-axial projections and clearances of approximately complimentary shape and the segment plates are form fixably joined to each other by pressing in of the projections into the clearances of the adjacent segment plate(s). 
     This type of positionally correct fixing of the segment plates to each other is, when these are constructed to be relatively thick, possible from the manufacturing technology in a simple manner thereby, that the projections are formed by the material from the stamped-out cavities, wherein the stamp stroke penetrates only through a portion, preferably the major portion, of the material thickness of the respective segment plate. 
     When the thickness of such plate shaped segments of the housing, in which the edge of their central clearances respectively define the groove basis of a groove extending through the central channel of the housing, the axial separation of the groove side wall forming segment plates or one of the natural break of these separation corresponding and/or the thickness of the plate segments, the groove side wall of two by a ring flange with respect to each other bordered housing ring grooves form, the thickness of the respective ring flanges or a natural break of the same correspondence, so can in principle all plate shape segments of the valve housing have the same thickness or be assembled of segment elements of the same thickness. 
     Consequently following of the inventive concept the valve piston can also be comprised of solidly with each other welded circular disk shaped segment plates, according to the base shape, so that also the axial width and radial depth of grooves of the piston and the thickness of such grooves with respect to each other separated piston flanges can be determined by the thickness of the segment plates or as the case may be a multiple of a minimum thickness. 
     The same is valid in concept for an intermediate sleeve introduced in the central channel of the housing, which coaxially encompasses the piston and for its part is comprised of ring disk shaped, solidly welded to each other segments of the same internal diameter d i . 
     Such an intermediate sleeve can in alternative embodiments of the valve be fixedly connected with the housing thereof or fixedly connected with the relative to the housing moveable valve piston and makes possible in both cases in simple manner the realization of ring channels of the housing, for example the piston, which channels form the flow paths of the valves. The intermediate sleeve can however also be formed of a moveable valve element moveable relative to the housing and a central, rigidly with this connected piston, via the displacement or rotational turning of which the various functional positions of the valve are selectable. 
     In a preferred embodiment of the inventive valve both the piston thereof as well also the intermediate sleeve thereof are formed moveable with respect to each other and relative to the housing. 
     In this embodiment the valve can be formed as servo-regulator valve, in which either the piston is employed as the desired position input element and the intermediate sleeve as the actual value feedback element or the housing as desired value input element and the piston as actual feedback element. 
     The until now described form of the valve housing, the piston and a piston coaxially encompassing intermediate sleeve is particularly suitable for an embodiment of the valve as turn slide valve, with easy movement of the valve elements relatively to each other, without detracting from the good sealing of the separation of flow paths set under high pressure against those which are in lower pressure levels, for example the ambient pressure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further details of the inventive hydraulic valve can be seen from the following description of illustrative embodiments of the same by reference to the drawings. There are shown: 
     FIG. 1 an inventive hydraulic valve with a housing formed of assembled plate shaped segments in schematic simplified prospective representation, partially in section along a vertical longitudinal middle plane of the housing along its central longitudinal axis as well as the longitudinal axis of pressure (P) and tank (T)-connection channels of the valve, partially as a view of its connection side outer surface, 
     FIG. 1 a  the valve according to FIG. 1 in section along its vertical longitudinal middle plane, 
     FIG. 1 b  the valve according to FIG. 1 in section along its transverse middle plane which contains the central longitudinal axis and extends at a right angle to the vertical longitudinal middle plane, 
     FIG. 1 c  the housing of the valve according to FIG. 1, in a sectional representation corresponding to FIG. 1, 
     FIG. 1 d  a view of the housing segment adjacent the connection side end segment of the housing, 
     FIG. 2 a simplified hydraulic switch diagram for explanation of the function of the valve according to FIG. 1, 
     FIG. 3 the plate shaped segments of the valve housing as well as likewise also plate shaped segment designed elements of the valve piston and one of the piston within the central valve housing channel coaxial surrounding intermediate sleeve in exploded, simplified perspective representation, the piston and intermediate sleeve segments in enlarged scale in comparison to the representation of the housing segment, 
     FIG. 3 a  a part of the piston and jacket segment according to FIG. 3 in comparatively enlarged scale, 
     FIG. 4 a further embodiment of a valve which is a constructional and functional analog of the hydraulic valve according to FIG. 1, and 
     FIG. 5 a servo-hydraulic valve in a supplied embodiment which is a constructional analog to the valve according to FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The hydraulic valve referenced overall in FIGS. 1 through 3 with is for purposes of explanation, without reduction of the scope of the invention, formed as a rotary slide valve, which has the function of a 4/3-way proportional valve. It has a blocking base position  0  in which a pressure (P) supply source connection  11  as well as a return flow (T) connection  12  are blocked against a user (A)-connection  13  as well as against a further user (B)-connection  14 , which are connected with the drive pressure spaces  16  and  17  of user represented in FIG. 2 as double acting linear hydraulic cylinder  18 . 
     By turning of the generally with  19  indicated piston of the valve  10  in the clockwise direction represented by arrow  21  in FIG. 1 and 3 about an azimuthal amount  1  the valve  10  can be placed in a function position I in which via a flow path  22  over the valve  10  the one drive pressure space  16  of the hydraulic cylinder  18  is connected which the P-supply connection  11  of the valve  10  and the other drive pressure space  17  of the hydraulic cylinder  18  via a flow path  22  of the valve  10  is connected with the T-connection  12  of the valve  10 , so that the piston  24  of the hydraulic cylinder  18  is moved in the direction of the arrow  26  of FIG. 2, according to the representation towards the right. 
     By turning of the valve piston  19  in the by the arrow  27  in FIG. 1 represented azimuthal direction 2 , in counter-clockwise direction, so then the valve  10  comes into its functional position II which is alternative to the functional position I, in which the other drive pressure space  17  of the user  18  via a flow path  28  of the valve  10  is connected with the P-supply connection  11 , on which the high output pressure P of the pressure supply aggregate  29  is available, while the in the functional position I of the valve  10  with the P-supply connection  11  of the valve  10  connected drive pressure space  16  of the user  18  now via a flow path  31  with the no-pressure tank  32  of the pressure supply aggregate  29  is connected, so that in the functional position II the valve  10  of the piston  24  of the user  18  moves to the left in the direction of the arrow  35  of FIG. 2, according to the representation. 
     For the valve  10  the characteristic is a presumed, that the hydraulic fluid flow, which in the functional positions I and II via the valve to the user  18  and from this can flow back into the tank  32  of the pressure supply aggregate  29 , are increasingly greater, the further the piston  19  is azimuthally deflected from its functional neutral base position  0  in which the user  18  is brought to rest. 
     Rotary slide valves, which fulfill the above described functions, as well as also functional analog linear slide valves, are generally known also in embodiments, in which for example in the base position of the valve the P- and T-connections thereof are connected with each other, so that the pump  33  of the pressure supply aggregate  27  can be operated in a circulating operation. 
     In distinction to conventional valves of the known type the housing generally referenced with  34  is formed by assembly of plate shaped, steel sheet comprising segments  36  through  46 , of which the large surface areas are connected with each other by brazing. 
     In a manner analogous to the segmented construction of the housing  34  the piston  19  of the valve  10  is formed by welding together circular disk shaped segments  48  through  56  according to the basic design. 
     A corresponding segmental construction is also possible for tubular shaped cylinder intermediate sleeve indicated with an overall  58 , which according to the desired base shape is comprised of ring shaped, solidly with each other welded segments  61  through  69 . 
     The housing  34  of the valve  10  has a central, through-going housing channel  71  (FIG. 1 c ) of segments of the length, which correspond to the thickness of the plate shaped housing segments  36  through  46 , which is formed by the edges sequentially following along the central longitudinal axis  72  of the central channel  71  and into each other transitioning central openings  73  through  83  of the plate shaped housing segments  36  through  46 . 
     The closed edged circular shaped openings  73 ,  74 ,  76 ,  78 ,  80 ,  82  and  83  of the plate shaped housing segments  36 ,  37 ,  39 ,  41 ,  43 ,  45  and  46  and the opening  75 ,  77 ,  79  and  81  of the remaining plate shaped housing segments  38 ,  40 ,  42  and  44  which have circular arch shaped edges over the main portion of the azimuthal area edged and of which the central openings are provided with slit shaped radial voids  86 ,  87  and  88  or as the case may be  89 , are provided coaxially with respect to the central longitudinal axis  72  of the central housing channel  71 . 
     Via ring groove segments  38 ,  40 ,  42  and  44 , which are pairwise provided between ring flange-segments  37 ,  39 ,  41 ,  43  and  45  of the plate shaped housing segments  36  through  46 , whereby the diameter d F  (FIG. 1 a ) of the central opening  74 ,  76 ,  78 ,  80  and  82  of the ring flange segment  37 ,  39 ,  41 ,  43  and  45  of the plate shaped housing segments is somewhat smaller than that (d N ) of the opening of the between respectively to ring flange segments provided ring groove segments  38 ,  40 ,  42  and  44  of the housing  34 , there are formed within the housing  34  central channel segmentwise radially widening ring grooves  91  through  94 , namely a T-(supply)-connection groove  91 , an A-(user)-connection groove  92 , a B-(user)-connection groove  93  and a P-(pressure supply)-connection groove  94 , wherein the A-connection groove and the B-connection grove  93  are provided between the T-connection groove  91  and the P-connection groove  94  and hereby the A-connection groove  92  is provided between T-connection groove  91  and the B-connection groove  93 , which is provided adjacent the P-connection groove  94 . 
     The connection end of the housing  34  is formed by the connection segment  36 , on which, in a bore shape customary for a 4/3 way valve standard connection bore holes for the P-supply connection  11 , the T-connection  12 , the A-user connection  13  and the B-supply connection  14  are provided. 
     The ring flange segment  37  adjacent that of the connection segment  36  of the housing  34  is provided with a circular clearance  12   1  aligned with the T-connection bore hole  12  of the connection segment  36 , which together with the connection bore hole  12  forms an in the radial bulge  86  of the central opening  77  of the T-groove segment  38  connecting T-longitudinal channel  96  (FIG. 1 a ), which via the radial bulge  86  formed transverse channel is in continuous communicating connection with the T-connection groove  91  of the housing  34 . 
     The associated housing segments  37  through  43  between the connection segment  36  and the P-ring groove segment  44  are provided with circular clearances  11   1  through  11   7  which are in alignment with the P-connection bore holes  11  of the connection segment  36  so that a continuous communicating connection exists between the P-supply connection  11  and the P-ring groove  94  of the housing  34 . The central longitudinal axis  72  of the central channel  71  of the housing  34  as well as the central longitudinal axis  98  of the T-longitudinal channel  96  and the central longitudinal axis  99  of the P-channel  97  lie in a common plane  101 , which according to the representation of FIGS. 1 and 1 d  is shown as a “vertical” longitudinal middle plane of the housing  34 . 
     The housing segments  37 ,  38  and  39  provided between the connection segment  36  and the A-ring groove segment  40  are provided with round clearances  13   1  and  13   2  or, as the case may be,  13   3  which are in alignment with the A-user connection bore hole  13  of the connection segment  36 , which overall form an A-longitudinal channel  102  (FIG. 1 b ), which connects in the radial projection  87  of the central opening  77  of the A-ring groove segment  40 , whereby again continuous communicating connection of the A-user connection  13  is established with the A-connection groove  92  of the housing  34 . 
     The housing segment  37  through  41  positioned between the connection segment  36  of the housing  34  and its B-ring groove segment  42  are provided with round clearances  14   1 , a  14   2    14   3 ,  14   4  and  14   5  which are in alignment with the B-connection bore holes  14  of the connection segment  36 , which form a B-longitudinal channel  103 , which connects in the channel formed by the radial projection  88  of the central opening  79  of the B-ring groove segment  42 , which is in communicating connection with the B-ring groove  93  of the housing  34 , so that also their continuous communication connection is provided with the B-use- connection  14  of the valve  10 . 
     The central longitudinal axis  104  of the A-longitudinal channel  102  and the central longitudinal axis  106  of the B-longitudinal channel  103  lie in the right-angular to the longitudinal plane  101  of the housing  34  running transverse middle plane  107  which transects the vertical longitudinal plane  101  along the central longitudinal axis  72  of the housing  34 . 
     The cumulative housing segments  36  through  46  are respectively provided with four circular round alignment clearances  108 , which are arranged in the same, four-fold axial symmetric grouping with respect to the common central longitudinal axis  72  of the central opening  73  through  83  of the housing segments  36  through  46  and in the same radial separation from the central longitudinal axis  72  as the P-connection bore hole  11  and the A- and B-connection bore holes  13  and  14  and are pair-wise arranged in planes, which lie at 45° to the central planes  101  and  107  of the housing  34 . 
     In the respective orientation of the plate shaped housing segments  36  through  46 , in which their T-channel clearances  12  and  121   1  their P-channel clearances  11  and  11   1  through  11   7  as well as their A-channel clearances  13  and  131  through  133  and their B-channel clearances  14  and  14   1  through  14   5  respectively with each other align, there are also respectively eleven of the alignment bore holes  108  positioned in alignment along the central longitudinal axis  111  through  114 , so that this configuration of the plate shaped housing segments  36  through  46  can be form fittingly joined by insertion of cylindrical-rod shaped fixing rods  116  through  119  of which the diameter, except for a negligible tolerance, corresponds to that of the alignment clearances  108 . By riveting the ends of the fixing rods  116  through  119  with the connection segment  36  and the operation side closure segment  46  of the housing  34  these plate shaped segments  36  through  46  are cumulatively form-fittingly joined in the appropriate configuration for welding together. 
     The azimuthal angular separation of the vertical axis  111  through  114  of the respective with each other aligned clearances  108  from the vertical longitudinal middle plane  101  of the housing  34  corresponds, in the represented embodiment selected for purposes of explanation, to respectively 30° . 
     The plate shaped housing segments  37  through  45  positioned between connection segment  36  and closure segment  46 , are further provided with through-going, circular-cylindrical clearances  121  of the same diameter, of which the central axis lies upon the same “bore” circle as the central longitudinal axis  111  through  114  of the alignment clearances  108  and from the vertical longitudinal middle plane  101  of the housing  34  are oriented in an angular separation of respectively 60°. These clearances  121  form the radial edges of the receiver channels for, for example, wire shaped brazing material, which extend along the length of the segment-package formed by the housing segments  37  through  45  and which are closed off to the outside by the connection segment  36  as well as by the closure segment  46  of the housing  34 . 
     Further brazing material receiving channels, which form self enclosed bore spaces of the housing  34 , are formed by pairwise with each other aligned axially, circular cylindrical clearances  122  of the housing segment  37  and  38 , which between the connection segment  36  and the this oppositely lying ring flange segment  39  are positioned or oriented, which form the one side axial bordering or limitation of the A-connection groove  92 . 
     Further self-enclosed receiving channels or chambers for brazing material are formed by circular cylindrical clearances  123  and of the same diameter, aligned with each other, in housing segments  40  through  45  between the ring flange segment  39  and the connection segment  46 , wherein these clearances  123  are provided diametrically opposite to the P-longitudinal channel  97  of the housing  34 . 
     A further brazing material receiving compartment, which is self enclosed, is bordered by aligned, circular-cylindrical clearances  124  of the respective housing segments  42  through  45 , which are provided between the central ring flange segment  41  of the housing  34  and its closure segment  46 . 
     A further, self enclosed receiving space for brazing material is finally bordered by with each aligned, circular cylindrical clearances  126  of the ring groove segment  44  and the ring flange segment  45 , which are positioned between the closure segment  46  and the this adjacent ring flange segment  43  of the housing  34  and by these are closed off in the axial direction. 
     The central longitudinal axis of the respective brazing receiver compartments, which extend between the central ring flange segment  41  and the connection segment  46  of the housing  34 , align with the central longitudinal axis  104  of the A-longitudinal channel  102  of the housing  34 , while the central longitudinal axis of the shorter brazing material reception space, which extends between the closure segment  46  and the ring flange segment  43 , which borders the P-groove  84  against the B-ring groove  93  of the housing  34 , aligns with the central longitudinal axis  106  of the B-longitudinal channel  103  of the housing  34 . 
     The connection segment  36 , the to this adjacent ring flange segment  37 , the upon this following T-ring groove segment  38  and the upon this following ring flange segment  39  of the housing  34  respectively have the same, essentially linear bordered outer contour. They have, as best seen in the detailed representation of FIG. 1 d , a quadrilateral base area  127 , which, right angularly to the central longitudinal center plane  101  of the housing  34  measured or determined, has the breadth B, a to this base area connecting, same sided-trapezoid shaped intermediate area  128 , of which the side edges  29  enclose with the central longitudinal center plane  101  an angle of 45°, and a to the trapezoid shaped intermediate area  128  connecting, the base shape according to a right-angled head-area  131 , of which the breadth measured right angularly to the vertical longitudinal center plane  101  of the housing  34  corresponds, in the embodiment selected for explanation, to ⅔ of the breadth B of the base area  127  and of which the parallel to the vertical longitudinal center plane  101  of the housing  34  measured height corresponds to ⅓ of the breadth B of the base area  127 . 
     The connection segment  46  corresponds with respect to the extension of its outer contour and its measurement or dimension to the quadric base-area  127  of the connection segment  36  or, as the case may be, the adjacent ring flange segment  37  represented in FIG. 1 d.    
     The housing segments  40  through  45 , which are provided between the closure segment  46  and the next adjacent ring flange segment  39 , of which the outer contour corresponds to that of the connection segment  36 , have identical outer contours  132 , drawn in FIG. 1 d  in dashed lines, which correspond to that of a cross, which both with respect to the vertical longitudinal center plane  101  of the housing  34  as well also with respect to the horizontal transverse center plane  107  thereof its symmetrically formed, wherein the linear running vertical and horizontal end face edges  133  and  134  of the cross shaped housing segment  40  through  45  align with vertical and horizontal limitation edges  136  or as the case may be  137  (FIG. 3) of the closure segment  46  and have the same length, which corresponds respectively to the half breadth B of the base of the closure element  46  and the connection element  36 . 
     Between the vertical and horizontal limitation edges  133  and  134  of the cross shaped housing elements are respectively circular bowed shaped concave bent transition areas  138 , of which the curvature center or focal points lie in the corners of the quadric base area  127 . 
     The closing off segment  46  is provided with circular cylindrical through-openings  139  in proximity to its corners for not shown anchor screws, by means of which the valve  10  is screwable onto a likewise not shown connection block. These anchor screws pass along the concave bent transition edges  138  of the cross shaped housing segment  40  through  45  and pass through elongated hole shaped insertion openings  141 , which in one of their arrangements of the circular round insertion openings  139  of the closing off segment  46  corresponding arrangements in immediate proximity to the corners of the quadrilateral base area  127  of the connection segment  36  and which is provided with this contour identical housing segment  37 ,  38  and  39 , wherein the longitudinal plane  142  of the elongate hole-shaped insertion opening respectively runs at 45° to the longitudinal middle plane  101  and to the transverse middle plane  107  of the housing  34  and contain the central longitudinal axis  143  of the circular shaped insertion openings  139  of the closing off segment  46 . The diameter d A  (FIG. 1 a ) of the central opening  73  of the connection segment  36  is somewhat larger than the diameter d F  of the central opening  74  of the adjacent housing segment  37 . Via the central opening  73  of the connection segment  36  waste oil exiting from the valve  10  can flow off to a waste oil channel of the not shown connection block. Also the diameter d A  of the circular round central opening  83  of the closing off segment  46  is larger than the diameter d F  of the adjacent cross-shaped housing segment  45  and, in the illustrated special working embodiment, also slightly larger than the diameter d A  of the central opening  73  of the connection segment  36 . A piston  19  engaging operating element  144  can extend through the central opening  83  of the connection segment  46 , as schematically shown in FIG. 2, by means of which the piston  19 , for example, by motor control, is rotatable in the alternative rotation directions  21  or  27  about the central longitudinal axis  72  of the valve  10 . 
     For a further explanation of the valve  10  an embodiment is envisioned wherein the intermediate sleeve  58  is introduced fixed in the central channel  71  of the housing  34  and the piston  19  is provided essentially rotatable, however axially non-displaceable. 
     The intermediate sleeve  58  is in this embodiment selected for illustrative purposes comprised of the ring disk shaped segments  61  through  69 , which, in substantial analogy to the construction or assembly of the housing  34  of the valve  10 , are welded rigidly with each other in coaxial arrangement with respect to their central longitudinal axis  72 . The ring disk shaped segments  61  through  69  of the intermediate housing  58  have all the same inner diameter d i  so that by the cumulativeness of the sleeve segments  61  through  69  a through-going, central, overall bore hole shaped channel  146  with circular-cylinder inner jacket surface is formed, in which the piston  19  is provided, which during the for explanation selected embodiment is produced in a segment construction manner analogous to that for the realization of the intermediate sleeve  58 , with its flange-segments  48 ,  50 ,  52 ,  54  and  56  pressure tight slideably and rotatably. 
     The intermediate sleeve  58  encompasses the self-enclosed ring flange-elements  61 ,  63 ,  65 ,  67  and  69  of the outer diameter d F  , as well as the between respective two of the ring flange element provided ring groove-segments  62 ,  64 ,  66  and  68  of the small outer diameter d R  (FIG. 1 a ). By these ring shaped housing segments  61  through  69  there are formed radially outer ring grooves  91 ′,  91 ′,  93 ′ and  94 ′ of the intermediate sleeve  58 , which together with the inner ring grooves  91  through  94  of the housing  34  produce essentially closed ring channels  91 ″ through  94 ″, namely the T-ring channel  91 ″, which is in communicating connection with the T-return flow connection  12  of the valve, the A-ring channel  92 ″, which is in communicating connection with the A-user connection  13  of the valve, the B-ring channel  93 ″, which communicates with the B-user connection  14  of the valve  10 , as well as the P-ring channel  94 ″, which is in communication connection with the pressure (P)-supply connection  11  of the valve  10 . 
     The axial thickness of the ring flange elements  61 ,  63 ,  65 ,  67  and  69  of the intermediate sleeve  58  correspond to the thicknesses of the ring flange segments  37 ,  39 ,  41 ,  43  and  45 , of which the central openings  74 ,  76 ,  78  and  80  or, as the case may be,  82 , the ring flange segments of the intermediate sleeve  58  are provided arranged in alignment of their ring face surfaces with the large surface bordering sides of the housing segments. 
     In the same sense the same thickness relation applies for the ring groove segments  62 ,  64 ,  66  and  68  of the intermediate sleeve  58  with respect to the thicknesses of the ring notch segments  38 ,  40 ,  42 , and  44  of the housing  34  through which it axially extends. 
     The mentioned thickness relationship applies also for the flange segment  48 ,  50 ,  52 ,  54  and  56  as well also to the groove-segments  49 ,  51 ,  53  and  55  of the piston  19  provided between each two of these flange segments with respect to these segments  48  through  56  coaxially encompassing ring shaped shell segments  61  through  69  of the intermediate sleeve  58 , in which the piston  19  is so provided that the outer end surfaces of its end flange segments  48  and  56  align with the outer ring face surface of the free ring flange segments  61  and  69  of the intermediate sleeve  58 . 
     For further explanation of details of the intermediate sleeve  58  and the piston  19  reference is now made to the enlarged segment representation of FIG. 3 a.    
     The ring notch segment  64  and  66  positioned respectively adjacent the central ring flange segment  65  of the intermediate sleeve  58 , which form the radial inner border of the A-ring channel  92 ″ or, as the case may be, the B-ring channel  93 ″, are provided with respectively two axial and radial through-going control slits  147  and  148  or, as the case may be,  149  and  151  which after the welding together of the ring shaped sleeve segments  61  through  69  are formed by erosion. The control slits  147  and  148  of the ring groove segment  64 , which radially internally border the A-ring space  92 ″, and the control slits  149  and  151  which form the radial inner borders of the B-ring space  93 ″ ring space segment  66  of the intermediate sleeve  58  are with respect to their central longitudinal axis  72  of the valve  10  respectively provided diametrically opposite to each other. The longitudinal bordering surfaces  152  and  153  of the inner control slit  147  and the longitudinal bordering surfaces  154  and  156  of the other control slit  148  of the A-groove segment  64  of the intermediate sleeve  58  run parallel to each other as well as parallel to the central longitudinal axis  72  of the valve  10 , wherein respectively two longitudinal bordering surfaces  152  and  156  or as the case may be  153  and  154  align with each other. 
     Accordingly, also in the B-ring groove segment  66  of the intermediate sleeve  58  the longitudinal bordering surfaces  157  and  158  as well as  159  and  161  of its control slits  149  and  151  run parallel to each other and pair-wise in alignment. 
     The common longitudinal central plane  162  of the control slits  147  and  148  of the A-groove segment  64  which contain the central longitudinal axis  72  of the rotation slide valve, runs at a right angle to that of the central longitudinal axis  72  containing common longitudinal central plane  163  of the two control slits  149  and  151  of the B-groove segment  166  of the intermediate sleeve  58 . 
     The between the radial inner longitudinal edges  164   1  and  164   2  of the control slit  147  and the radial inner longitudinal edges  164   3  as well as  164   4  of the control slit  148  of the A-groove segment  64  as well as the between the radial inner longitudinal edges  166   1  and  166   2  of the control slit  149  and the between the radial inner longitudinal edge  166   3  and  166   4  of the control slit  151  of the B-groove segment  66  of the intermediate sleeve  58 , azimuthal width of the control slit  147  and  148  or as the case may be  149  and  151  correspond in the illustrative embodiment respectively to 90°. 
     The A-groove segment  64  and the B-groove segment  66  of the intermediate sleeve  58  are in the illustrative embodiment are oriented so “turned” with respect to each other, that the longitudinal central plane  162  and  163  of the control slits  147  and  148  of the A-groove segment  164  or as the case may be the control slit  149  and  151  of the B-groove segment  66  respectively enclose an angle of 45° with the vertical longitudinal plane  101  of the housing  34 . 
     Also the piston  19  of the valve  10  which in the intermediate sleeve  58  is rotatably mounted wherein its flange-segment  48 ,  50 ,  52 ,  54  and  56  fluid tight-slideably on the inner jacket surface of the intermediate sleeve  58  lies, is in a with respect to the axial thickness of its piston segment  48  through  56  the axial thickness of the corresponding jacket segment  61  through  69  corresponding segment-constructionally of its ring disk shaped piston segments  48  through  56  formed, which again are solidly welded to each other. 
     In the piston  19 , for discussion of which reference can in particular be made to the detailed representation of FIG. 3 a  as well as the longitudinal sectional representation of FIGS. 1 a  and  1   b , is by the connection side end flange segment  48 , which has the same diameter d i  as the next adjacent separation flange segment  50  and which forms in the intermediate T-groove segment  49  of the piston  19  a T-ring groove  91 ′″, which via radial through-going transverse channels  165  of the T-ring groove segment  62  of the intermediate sleeve  58  is in constant communication connection with the T-ring space  91 ″. 
     Through the other, on the operating side of the valve  10  provided end flange segment  56  of the piston  19  which has the same diameter d i  as the next adjacent B-separation flange segment  54  and which between this position is provided P-groove segment  55  of smaller outer diameter is formed a P-ring groove  94 ′″, which via radial transverse channels  170  of the T-ring groove segment  68  of the intermediate sleeve  58  is in constant communicating connection with the P-ring space  94 ″ of the valve  10 . 
     Between the A-separation flange segment  50  and the central ring flange segment  52  of same diameter d i  of the piston  19  is provided, within the A-ring groove segment  64  of the intermediate sleeve  58 , an A-control segment  51  of the piston  19 , which is provided with a total of four radial outer open longitudinal grooves  167   1  through  167   4  extending between the A-separation flange segment  50  and the central ring flange  152 . 
     A B-control segment  53  of the piston  14  is provided between the B-separation flange segment  54  and the central ring flange segment  52  of the piston  19  within the B-ring notch segment  66  of the intermediate sleeve  58 , which again is provided with a total of four radially outer open longitudinal notches  168   1  through  168   4  extending themselves between the B-separation flange segment  54  and central ring flange segment  52  of the piston  19 . The longitudinal grooves  167   1  through  167   4  of the A-control segment  51  and the longitudinal grooves  168   1  through  168   4  of the B-control segment  53  are provided in groups of four axially symmetric with respect to the central longitudinal axis  72 ′ of the piston  19 , wherein the longitudinal grooves  167   1  through  167   4  of the A-control segment  51  and the longitudinal grooves  168   1  through  168   4  of the B-control segment  53  of the piston  19  pair-wise are aligned with each other. These in longitudinal direction pair-wise with each other aligned longitudinal notches of the A-control segment  51  and the B-control segment  53  are connected by closed right-angled edged throughput channels  169   1  through  169   4  of the central ring flange segment  52  appropriately communicating pair-wise with each other. 
     The piston-fixed common longitudinal central plane  173  of the each other diametrically oppositely lying longitudinal grooves  167   1  and  167   3  of the A-control segment  51 , which each other diametrically oppositely lying arranged throughput channels  169   3  and  169   3  of the central ring flange  52  as well as the diametrically oppositely lying longitudinal grooves  168   1  and  168   3  of the B-control segment  153  is also the common longitudinal central plane of the diametrically oppositely lying P-throughput channels  176  and  177  of the B-separation flange segment  154  of the piston  19 , via which the respective, with each other aligned, longitudinal grooves of the A-control segment  51  and the B-control segment  53  as well as the with this communicating throughput channel  169   1  and  169   3  of the central ring flange segments  52  with the P-ring notch  94 ′″ of the piston  19  are in constant communicating connection. 
     The to the first mentioned piston fixed longitudinal central plane  173  right angled running, piston fixed, common longitudinal middle plane  178  of the respective other two, each other diametrically oppositely lying longitudinal grooves  167   2  and  167   4  of the A-control segment  51 , the diametrically oppositely lying arranged through channel  169   2  and  169   4  of the central ring flange segment  52  as well as the further diametrically oppositely lying longitudinal groove  168   2  and  168   4  of the B-control segment  53  is also a common longitudinal middle plane of the diametrically oppositely lying T-throughput channels  171  and  172  of the A-separation flange segment  50  of the piston  19 , via which the respective with each other aligned longitudinal notches  167   2  and  167   4  as well as  168   2  and  168   4  of the A-control segment  51  or as the case may be B-control segment  53  as well as this communicating throughput channels  169   2  and  169   4  of the central ring flange segment  52  are in constant communicating connection with the T-ring notch  91 ′″ of the piston  19 . 
     The effective azimuthal width of the longitudinal notches  167   1  through  167   4  of the A-control segment as well as longitudinal groove  168   1  and  168   4  of the B-control segment  53  of the piston  19 , which is determined by the angular separation of the radial outer longitudinal edge  179  and  181  of their parallel to each other running groove side edge surfaces  182  and  183 , corresponds to 90° and is therewith at the same time the azimuthal separation of the radial inner longitudinal edge  164   1  and  164   2  as well as  164   3  and  164   4  of the axial control slit  147  and  148  of the A-ring groove segment  64  of the intermediate sleeve  58  (the same relation applies for the longitudinal grooves  168   1  through  168   4  of the B-control segment  53  of the piston  19  and the with this coaxial ring groove segment  66  of the intermediate sleeve  58 ). 
     An output present on the P-supply connection  11  of the valve pressure P of the pressure supply aggregate  29  (FIG. 2) is coupled in via the P-longitudinal channel  97  (FIG. 1 a ) of the housing  43  also in this P-ring channel  97 ″ and from the same via the radial transverse channel  170  of the intermediate sleeve  58  in the P-ring groove  94 ′″ of the piston  19  as well as in the two P-control channels  184  and  186  (FIG. 1 b ), which extends itself beginning with the P-throughput channels  176  and  177  of the B-separation flange segment  54  of the piston  19  up to the A-separation flange segment  50  of the piston  19 , which closes off the P-control channel  184  and  186  against the T-ring groove  91 ′″ if the piston  19 . Further there are T-control channels  187  and  188  (FIG. 1 a ) which, beginning with the T-throughput channels  171  and  172  of the A-separation flange segment  50 , extend up to the B-separation flange segment  54  of the piston  19  and through these against the P-ring groove  94 ′″ of the piston  19  are blocked off, connected communicating with the tank  32  of the pressure supply aggregate  29 . 
     In the base position  0  of the valve  10  the P-control channels  184  and  186  as well as the T-control channels  187  and  188  are blocked off against the A-connection groove  92  and the B-connection groove  93  of the housing  34 . This blockage function of the valve  10  in its base position  0  is then given, when the control slits  147  and  148  of the A-ring groove segment  64  as well as the control slits  149  and  151  of the B-ring groove segments  66  of the intermediate sleeve  58  through respectively two of the diametrically oppositely lying in cross-section sector shaped longitudinal posts  189   1  through  189   4  and  191   1  through  191   4  of the A-control segment  51  or as the case may be the B-control segment  53  of the piston  19 , with their longitudinal grooves  167   1  through  167   4  or as the case may be  168   1  through  168   4  azimuthally block off against each other, are radially closed. 
     This is in the embodiment  10  selected for explanation purposes, for which a housing-fixed arrangement of the intermediate sleeve  58  was presumed, then the case, when the piston fixed, respectively common longitudinal middle plane  192  and  193  of the pair-wise oppositely arranged sector shaped longitudinal cross-pieces  189   1  through  189   4  of the A-control segment  151  or as case may be the B-control segment  53  of the piston  19  have the same orientation as the housing fixed longitudinal middle plane  162  and  163  of the control slits  147  and  148  of the A-ring groove segment  64  or as the case may be the control slit  149  and  151  of the B-ring segment  66  of the intermediate sleeve  58  which with the vertical longitudinal middle plane  101  of the housing  34  encloses an angle of respectively 45°. 
     The base position  0  of the valve  10  corresponds to the configuration of the ring disk shaped segments  61  through  69  of its intermediate sleeve  58  shown exploded along the axis  72   1  in the FIGS. 3 and 3 a  as well as the circular disk shaped segments  48  through  56  of the valve piston  19 . 
     In this base position the radial outer longitudinal edges  179  and  181  of the groove side-wall-longitudinal surfaces  182  and  183 , between which pair-wise also the curved edges of the sector shaped longitudinal cross-member  189   1  through  189   4  as well as  191   1  through  191   4  of the A-control segment  51  or as case may be the B-control segment  53  of the piston  19  extend, with the same registry with the radial inner longitudinal edges  164   1  through  164   4  and  166   1  through  166   4  of the control slits  147  and  148  of the A-ring groove segment  64  of as the case may be the control slits  149  and  151  of the B-ring groove segment  166  provided. 
     Beginning with the base position  0  of the valve  10 , this arrives by turning of the piston  19  in the direction of the arrow  21  of FIG. 3 in the along the central axis  72   2  exploded represented configuration of its intermediate sleeve segments  61  through  69  as well as the piston segments  48  through  56 , in which by overlapping the interstitial space cross-sections of the longitudinal grooves  167   1  and  167   3  of the A-control segment  51  of the piston  19  which with the interstitial space cross-sections of the control slits  147  and  148  of the A-ring groove segment  64  of the A-user connection  13  of the valve  10  is connected with its P-supply connection  11  and through the overlapping of the interstitial space cross-sections of the longitudinal grooves  168   2  and  168   4  of the B-control segment  53  of the piston  19  with the interstitial space cross-sections of the control slits  149  and  151  of the B-ring segments  66  of the B-user connection  14  of the valve  10  is connected with its T-return flow connection  12 , that is, the valve  10  assumes the functional position I. 
     Alternatively thereto, the valve  10  is brought into, again beginning with its base position  0 , by rotation of its piston  19  in the direction of the arrow  27  in FIG. 3 in the along the central longitudinal axis  72   3  of in FIG. 3 exploded represented configuration of its intermediate sleeve segments  61  through  69  as well as the piston segments  48  through  56 , in which through the overlapping of the interstitial space cross-sectional segments of the longitudinal grooves  167   2  and  167   4  of the A-control segments  51  of the piston  19  with the interstitial space cross-sectional segments of the control slit  147  and  148  of the A-ring groove segment  64  the A-user connection  13  of the valve  10  is connected with its T-return flow connection  12  and through the overlapping of the interstitial cross-sectional segments of the longitudinal grooves  168   2  and  168   4  of the B-control segments  53  of the piston  19  with the interstitial space cross-sectional segments of the control slits  149  and  151  of the B-ring groove segments  66  of the intermediate sleeve  58  the B-supply connection  14  of the valve  10  is connected with its P-supply connection  11 , that is, the valve  10  assumes its functional position II. 
     A hydraulic valve  10 ′ with functional positions and path connections explained by way of example on the basis of FIGS. 1 through 3 is also, as represented in schematically simplified manner in FIG. 4, realizable in the manner, that the housing  34  of the valve  10  is fixedly connected with its piston  19 ′ and the intermediate sleeve  58 ′ is provided rotatably relative to the unitary construction formed by the piston  19 ′ and the housing  34 ′. 
     As control drive for the housing  58 ′ there may suitably be employed for example an electric motor  194  with reversible direction of rotation, which drives a pinion gear  196 , which engages with an outer teething  197  of an end segment  198  of the intermediate sleeve  58 ′ extending out from the housing  34 ′. 
     This type of control is also envisioned in the rotary slide valve  10 ″ represented in FIG. 5, in which both the intermediate sleeve  58 ″ as well as also the central piston  19 ′ are constructed to be rotatable relative to each other and to the housing  34 ″. This rotary slide valve  10 ″ is formed as a follow-up control valve, which is employable for example for drive control of a rotary-hydraulic motor  199 , of which the drive shaft  201  is fixed against rotation or via a not shown slit free drive, that is, a tooth gear drive without play, is rotatingly moveably coupled with the piston  19 ″, which is employed as “mechanical” feedback element for the respective azimuthal position of the drive shaft  201  of the hydraulic motor  199 . The desired value input for this position is achieved by the driving of the intermediate sleeve  58 ″ by means of the pinion  196  driven electric motor  194 , which in this case advantageously is digitally controllable, that is, is controllable by a series of electrical impulses, wherein each of these impulses corresponds to a rotation of the pinion  196  about a defined, incremental rotation angle Δφ, which is also associated with an incremental rotation angle δφ of the motor shaft  201  of the hydraulic motor  199 . The relationship δφ/Δφ is hereby determined by the transmission translation, with which the rotatorial movement of the drive shaft  202  of the drive control motor  194  transmits upon the intermediate sleeve  58 ″ and the rotation of the drive shaft  201  of the control hydraulic motor  199  or as the case may be upon the piston  19 ″ is fed back to the servo-regulator valve  10 ″. 
     It is understood, that a follow up control valve constructed as a rotary slide valve of the type described with reference to FIG. 5 could also be realized in the manner, that the desired position value-input for the drive-controlled element is produced by electric controlled drive of the valve piston and the position-actual-value feed-back is produced by rotational coupling of the drive controlled element with the intermediate sleeve of the follow up control valve. 
     In particular in the embodiment of valves  10  and  10 ″ discussed on the basis of FIG. 4 and 5 in which the intermediate sleeve  58 ′ or as the case may be  58 ″ moveably is provided, it is advantageous, that the under high initial pressure of the pressure supply aggregate  29  existing P-throughput channel  169   1  and  169   3  of the central ring flange segment  52  of the piston as well the P-throughput channel  176  and  177  of the B-separation flange segment  54  within its segments  53  and  54  is closed edged, so that in the area of the central ring flange segment  52  as well as in the area of the B-separation flange segments  54  a through the pressure caused radial force upon the intermediate sleeve  58 ′ or as the case may be  58 ″ is avoided, which would have the tendency to spread apart the this ring flange segment  52  and  54  of the piston  19  circumscribing ring flange element  56  and  57  of the intermediate sleeve and thus contribute to an overall difficulty of movement of the intermediate sleeve. This reduction of the tendency to spreading apart and therewith to increase rubbing friction upon the housing acting forces is, thanks to the segment construction manner of the piston  19 , in simple manner made possible, which therewith also in functional respects imparts the advantage of a high functional reliability.