Abstract:
A compact electrohydraulic motor pump unit comprising a housing which forms a reservoir for a pressurized fluid and contains an electric motor, and which comprises a first housing sealing section, a second housing sealing section and a tubular housing mid-section therebetween. Disposed between the second housing sealing section and the electric motor is a support plate for a pump which can be driven by the electric motor via a motor shaft and by which pressurized fluid can be conveyed on a pressurized flow path to a delivery connection. In such a conventional type motor pump unit, a circumferential seal, which is intended to seal off the interior of the housing, is located both between the support plate and the housing mid-section and between the support plate and the second housing sealing section. In order to reduce the number of sealing points between the interior and the exterior of the housing, the delivery connection is located externally on the second housing sealing section, and the second housing sealing section and the tubular housing mid-section, sealing off the interior of the housing from the outside, rest against one another peripherally and the support plate is located entirely within the housing.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The invention relates to a compact electrohydraulic motor pump unit. 
     Such a motor pump unit has been disclosed by DE 299 06 881 U1. This unit possesses a housing which forms a reservoir for a pressurized fluid and in which an electric motor is located. A housing mid-section is of tubular form and closed off at one end face by a first housing lid or, in more general terms, by a first housing sealing section. In front of the other end face of the housing mid-section is located a second housing sealing section which, in the conventional motor pump unit, does not however lie directly on the housing mid-section. Between the second housing sealing section and the housing mid-section, instead, is located a support plate on which a radial piston pump, drivable via the motor shaft of the electric motor, and a similarly drivable gear pump are fixed. Located in the support plate are ducts via which pressurized fluid can be conveyed by the pumps to two delivery connections externally on the support plate. 
     In the conventional motor pump unit, the interior of the housing has to be sealed off peripherally from the outside between the housing mid-section and the first housing sealing section, between the housing mid-section and the support plate and between the support plate and the second housing sealing section. This is disadvantageous, as the risk of a leakage increases with the number of sealing points and with the length of the seals. Today, however, great importance is attached to clean production areas and the protection of the environment. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention further to develop such a compact electrohydraulic motor pump unit such that the number of sealing points between individual housing sections is reduced. 
     This object is achieved, according to the invention, in that, in a compact electrohydraulic motor pump unit of the introductory-mentioned type, the delivery connection is located externally on the second housing sealing section, in that the second housing sealing section and the tubular housing mid-section, sealing the interior of the housing from the outside, rest on one another peripherally, and in that the support plate is located entirely within the housing. In a motor pump unit according to the invention, therefore, the support plate has lost its function as a housing section by comparison with the motor pump unit in accordance with the above-mentioned state of the art. The second housing sealing section lies, like the first housing sealing section, directly on the housing mid-section, so that there are now only two peripheral sealing points of large diameter. The risk of a leakage to the exterior is significantly reduced thereby. 
     Advantageous embodiments of a compact electro-hydraulic motor pump unit according to the invention are provided. 
     In an effort to keep down the installation effort required for a motor pump unit according to the invention, a tube is provided which lies in the pressurized flow path from the pump to a delivery connection on the second housing sealing section and is connected axially by a plug-in fitting to the second housing sealing section at one end and connected axially by a plug-in fitting to a counterpart at the other end. This permits particularly simple assembly in the axial direction of the motor shaft of the electric motor. In this case, in principle, axial plugging-in of the tube is also possible if although the ends of the tube point in the axial direction they are not aligned with one another and the tube is bent. Preferably, however, the tube is straight and extends axially. Special working steps for bending the tube are thereby avoided. Preferably, the tube is plugged into a bore at each of its ends. The diameter of the tube may then be smaller than in a case where the ends are fitted onto pegs. 
     The tube lies in the pressurized flow path of the pressurized fluid, in which pressure pulses occur, as a result of which the tube might perform small axial movements because of the dimensional tolerances arising in the dimensions of the components and on the tube itself. In order to prevent this, and wear associated therewith and the evolution of noise attributable thereto, the invention provides that the tube is pressed against the other section in one axial direction by a spring element, which is tensioned between the tube and one section of the two sections comprising the counterpart and the second housing sealing section. The spring element is advantageously tensioned between an external shoulder of the tube and the counterpart or the second housing sealing section. It is particularly economical of space and cost-effective for the spring element to be formed by an O-ring. In order to obtain a sufficiently large supporting surface for the spring element even when the tube wall thickness is slight, the invention provides for the insertion of a shim between the spring element and the tube. 
     Compact electrohydraulic motor pump units of substantially the same construction customarily form a complete series with different structural sizes and different specifications. In order to be able to use the same tube with as many versions as possible, the invention provides that a length-compensation disk is threaded onto the turned-down end of a tube. Preferably, the length-compensation disk lies between the O-ring and the external shoulder of the tube, so that it is retained on the tube before and during assembly of the tube by the O-ring, which is pushed onto the tube with tension. 
     Depending upon the side of the support plate on which a pump is disposed, and depending on what kind of pump is involved, a tube extends, between the support plate and the second housing sealing section, or, between a connecting flange of the pump and the second housing sealing section. The latter will be the case, for example, if a gear pump or vane-cell pump is disposed on the side of the support plate remote from the electric motor and comprises a radially descending delivery outlet. The former will be the case, primarily, if the pump is seated on the side of the support plate facing toward the electric motor. 
     It is be desirable to be able to use compact electrohydraulic motor pump units flexibly, with one pump or with two pumps which can convey in different hydraulic circuits, and adjusted to the spatial conditions at a machine tool for which such units are primarily used. Therefore, the second housing sealing section is provided with two delivery connections and two plug-in connections for a tube. If two pumps are driven by the electric motor, one can pump to one delivery connection and the other to the other delivery connection. In this case, the form of the pressurized flow paths is such that either one pump or, only because of different installation, the other pump pumps to one delivery connection. Similarly, the sections may be so assembled that, where only one pump is present, either one delivery connection or the other delivery connection is used. In particular, the support plate has two plug-in connections for a tube, a tube extending between one plug-in connection of the support plate and one plug-in connection of the second housing sealing section and other plug-in connection of the support plate being closed off. In this case, therefore, a pump in whose pressurized flow path ducts also lie within the support plate can pump, by selection of the appropriate plug-in connection on the support plate, to one delivery connection or to the other. Installation of the support plate in different angular attitudes relative to the axis of the motor shaft would, admittedly, permit pumping to one delivery connection or to the other delivery connection even with only one plug-in connection in the support plate and two plug-in connections in the second housing sealing section. In that case, however, the two plug-in connections in the housing sealing section would have to be located at the same distance from the axis of the motor shaft. This again is not in all cases compatible with the arrangement of the plug-in connections in the second housing sealing section that is necessary for the use of two pumps. 
     Special embodiments with two pumps are also provided by the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the embodiment shown in FIGS. 1 to  4  a plurality of conveying units  41  of a radial piston pump  40  are fixed on the side of the support plate  35  facing toward the electric motor  11 . Specifically, the conveying units are axially located between the support plate  35  and an annular disk  42 , which is fixedly connected to the support plate  35  via screws  43  passing laterally by the conveying units  41  and guiding the conveying units laterally. The conveying units aspirate pressurized liquid from the interior of the housing  10  and release it via pressure valves  44  into a ducting system of the support plate  35  which lies in a flow path to one of two connecting sockets  45  on the cover  13 . It is apparent from figure 4 that the two connecting sockets  45  are disposed at an angular distance of 90° apart on the cover  13 . The pressure valves  44  substantially consist of, in each case, a spherical closing body, a closing spring and a cylindrical housing which plugs at one end into the support plate  35  and at the other end into the cylinder of a conveying unit  41  and thus helps to mount the conveying units  41 . The pistons  47  of the conveying units  41  are pressed by a spring  48  against a cam  49  of a camshaft  50 , which is inserted into the motor shaft  23  and is rotatably mounted in a ballbearing  51  received by the support plate  35 . 
     When a drive is provided by the electric motor  11 , in the example of embodiment shown in FIGS. 1 and 2, the conveying units  41  of the radial piston pump convey pressure medium via the pressure valves  44 , the ducting system in the support plate  35 , the tube  60  and a duct formed by one or more bores in the cover  13  to a connecting cap  45 , which may be referred to as the first connecting cap. The gear pump  65  pumps via the connecting flange  66 , the tube  68  and a duct in the cover  13  to the second connecting cap  45 . With the compact unit, therefore, hydraulic consumers lying in two separate hydraulic circuits can be supplied with pressure medium. It may sometimes be desirable here, with the same arrangement of the unit on a machine, for the radial piston pump to pump to the second connecting cap and the gear pump to the first connecting cap. In order for it to be possible to provide the kind of alternative embodiment shown in FIG. 3 in an easy manner, simply by means of a different assembly of the parts, the second insertion bore  52  is present in the support plate  35 . The insertion bore  52  closed off by the screw  55  in the embodiment shown in FIGS. 1 and 2 is in fact precisely aligned with the second insertion bore  61  of the cover  13 . The long tube  60  can thus readily be plugged into the second insertion bore of the support plate  35  and the second insertion bore  61  of the cover  13 . In that case, the other insertion bore  52  of the support plate  35  is closed off by a screw  55 . For the flow path between the gear pump  65  and the other connecting cap on the cover  13 , a connecting flange  66  is used in which the insertion bore  67  lies on the other side from the delivery connection of the gear pump  65 , as is clearly apparent from FIG.  3 . Apart from the two different connecting flanges  66 , therefore, no different parts are necessary in order to produce the two alternative embodiments, either that according to FIGS. 1 and 2 or that according to FIG.  3 . 
     A plurality of examples of embodiment of a compact electrohydraulic motor pump unit according to the invention are shown in the drawings. The invention will now be explained in detail with reference to the figures of those drawings. 
     In the drawings: 
     FIG. 1 shows a longitudinal section through the first example of embodiment, wherein a plurality of conveying units of a radial piston pump are fixed on the side of the support plate facing the electric motor and a gear pump is fixed on the side of the support plate remote from the electric motor, an axially plugged-in tube lying in the pressurized flow path of each pump; 
     FIG. 2 shows a longitudinal section through part of the unit according to FIG. 1, the section extending in a different plane; 
     FIG. 3 shows an alternative embodiment of the unit according to FIGS. 1 and 2, in which the delivery connections for the two pumps are exchanged by comparison with the embodiment shown in FIGS. 1 and 2; 
     FIG. 4 shows a plan view of the unit according to FIGS. 1 and 2, or the unit according to FIG. 3, in which the positions of the two existing delivery connections become clear; 
     FIG. 5 shows a longitudinal section through a second example of embodiment, wherein two gear pumps are disposed on the side of the support plate remote from the electric motor; 
     FIG. 6 shows a third example of embodiment, wherein a single gear pump is disposed on the side of the support plate remote from the electric motor; 
     FIG. 7 shows a fourth example of embodiment with the conveying units of a first radial piston pump on the side of the support plate facing toward the electric motor and with the conveying units of a second radial piston pump between the support plate and one housing cover; and 
     FIG. 8 shows a compact electrohydraulic motor pump unit without a support plate in the interior of the housing, in which a plurality of conveying units of one radial piston pump are fixed on a housing cover, the latter being provided with an axial plug-in connection in order to enable it to be used, without substantial further modification, with motor pump units in accordance with embodiments 1 to 7. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The electrohydraulic motor pump units shown comprise a housing  10  which, first, fulfills the function of the reservoir for a pressurized fluid used for working and, in addition, may also be regarded as a housing of an electric motor  11 . This housing comprises, as essential parts, a first housing cover  12 , a second housing cover  13  and a housing mid-section  14 . This is a section cut from a profiled tube produced from an aluminum alloy and has been subjected to final machining. Retaining webs  15  run axially along the inside of the housing mid-section  14  and, over a certain distance, have been entirely removed or, in some cases, removed at various heights from the end face of the housing mid-section  14 . The housing cover,  12  or  13 , is centered by means of a centering collar  17  in a turned recess  16  in each end face of the housing mid-section  14 , in which the retaining webs  15  have been completely removed. A groove runs around the centering collar, in which groove a gasket  18  is received, by means of which the gap separating a cover from the housing mid-section is sealed. Overall, therefore, there are only two such sealing points present, with large diameters. 
     The housing cover  12  is fixedly connected to the housing mid-section  14  by means of individual small screws  19 , which are driven radially through the housing mid-section  14  into the centering collar  17 . A filling connector  20  for the pressurized fluid and a terminal box  21  for the electrical connection of the connections of the electric motor and an electric fan with a connecting cable, if present, are provided on the cover  12 . In addition, the drive shaft  23  of the electric motor  11  is rotatably mounted via a ballbearing  22  in the cover  12 . The stator  26  of the electric motor  11  is pressed into the housing mid-section. 
     The second housing cover  13  is retained on the housing mid-section  14  via long tie-rods  27 , which extend axially between the retaining webs  15  and are screwed into inward-projecting eyelets of the centering collar  17  of the cover  13 . The tie-rods extend from the housing cover  13  to beyond the electric motor  11  and pass, in individual bores, though an annular disk  28  which is laid on shoulders of the retaining webs at a short distance from the first housing cover  12 . A nut  29  is screwed onto the end of each tie-rod  27 , projecting in the direction of the cover  12  beyond the annular disk  28  and provided with a thread, and tightened against the annular disk  28 . 
     In the motor pump units shown in FIGS. 1 to  7 , a support plate  35 ,  75  or  80 , which rests on shoulders of the retaining webs  15  produced by partial cutting-away is located between the cover  13  and the electric motor  11 , entirely within the housing  10 . The support plate is pressed onto the shoulders of the retaining webs  15  and held stationary in the housing  10  by a number of machine screws  36  which pass through it from the side of the cover  13  and are driven into threaded bores  37  in the retaining webs  15 . 
     In the embodiment shown in FIGS. 1 to  4 , a plurality of conveying units  41  of a radial piston pump  40  are fixed on the side of the support plate  35  facing toward the electric motor  11 . Specifically, the conveying units are axially located between the support plate  35  and an annular disk  42 , which is fixedly connected to the support plate  35  via screws  43  passing laterally by the conveying units  41  and guiding the conveying units laterally. The conveying units aspirate pressurized liquid from the interior of the housing  10  and release it via pressure valves  44  into a ducting system of the support plate  45  which lies in a flow path to one of two connecting sockets  45  on the cover  13 . It is apparent from FIG. 4 that the two connecting sockets  45  are disposed at an angular distance of 90° apart on the cover  13 . The pressure valves  44  substantially consist of, in each case, a spherical closing body, a closing spring and a cylindrical housing which plugs at one end into the support plate  35  and at the other end into the cylinder of a conveying unit  41  and thus helps to mount the conveying units  41 . The pistons  47  of the conveying units  41  are pressed by a spring  48  against a cam  49  of a camshaft  50 , which is inserted into the motor shaft  23  and is rotatably mounted in a ballbearing  51  received by the support plate  35 . 
     The outlets of the pressure valves  44  are connected to one another via ducts substantially extending in a radial plane of the support plate  35 . An axial bore  52 , which starts from the side of the support plate  35  remote from the conveying units  41 , is provided with a thread on a narrower inner section and comprises an annular groove  53  for receiving a gasket  54  in an outer, wider section, opens into these ducts at each of two points therein. One of the two axial bores  52  is closed off by a screw  55 . A straight and axially extending tube  60  is plugged into the other axial bore  52  by an externally machined end section. This tube lies in the flow path which leads from the pressure valves  44  of the conveying units  41  to one of the two connecting sockets  45  on the cover  13 . This flow path is sealed off from the interior of the housing  10  at the transition from the support plate  35  to the tube  60  by a gasket  54  lying in the groove  53 . The tube  60  bridges the distance between the support plate  35  and the cover  13 , which comprises a bore  61  which is axially aligned with a bore  52  of the support plate  35  and into which the tube  60  is plugged axially by its second end section, which is likewise machined. The distance between the two axial shoulders, formed by the machining operations at the two ends, of the tube  60  is less than the clear distance between the support plate  35  and the cover  13 . This is arranged in this way in order for it to be possible to push one or more compensating disks  62 , a shim  63  and an O-ring  64  onto one end section of the tube, the O-ring  64  being seated with prestress on the tube and holding the compensating disks  62  and the shim  63  between itself and one axial stop of the tube. The O-ring  64  is used as a spring element which presses the tube  60 , via the compensating disks  62  and the shim  63  by means of the axial stop on the other end section against the support plate  35 . In this manner, tolerances relating to the clear distance between the support plate  35  and the cover  13  are compensated. In addition, the same tube  60  can be used for different embodiments, differences in the clear distance being compensated for by the use of different numbers and/or thicknesses of compensating disks and/or shins. 
     On the side of the support plate  35  remote from the electric motor  11  is fixed a gear pump  65 , which comprises, externally on its jacket surface, a delivery connection onto which a connecting flange  66  is screwed. The latter possesses an insertion bore  67 , which extends axially, opening toward the cover  13 , and is in connection with the delivery connection of the gear pump  65  through out-of-true bores within the connecting flange  66 . The cover  13  possesses, axially aligned with the bore  67 , a second insertion bore  61  which is in connection via ducts in the cover  13  with the delivery aperture in the second connecting cap of the cover  13 . Between the second insertion bore  61  and the insertion bore  67  in the connecting flange  66  extends a tube  68  which, like the tube  60 , is straight and extends axially, possesses machined end sections, is pressed like the tube  60  by an O-ring  64 , compensating disks  62  and a shim  63  by means of an axial shoulder against the connecting flange  66 , and is plugged into the insertion bores in a sealing manner. 
     When a drive is provided by the electric motor  11 , in the example of embodiment shown in FIGS. 1 and 2, the conveying units  41  of the radial piston pump convey pressure medium via the pressure valves  44 , the ducting system in the support plate  35 , the tube  60  and a duct formed by one or more bores in the cover  13  to a connecting cap  45 , which may be referred to as the first connecting cap. The gear pump  65  pumps via the connecting flange  66 , the tube  68  and a duct in the cover  13  to the second connecting flange  45 . With the compact unit, therefore, hydraulic consumers lying in two separate hydraulic circuits can be supplied with pressure medium. It may sometimes be desirable here, with the same arrangement of the unit on a machine, for the radial piston pump to pump to the second connecting cap and the gear pump to the first connecting cap. In order for it to be possible to provide the kind of alternative embodiment shown in FIG. 3 in an easy manner, simply by means of a different assembly of the parts, the second insertion bore  52  is present in the support plate  35 . The insertion bore  52  closed off by the screw  55  in the embodiment shown in FIGS. 1 and 2 is in fact precisely aligned with the second insertion bore  61  of the cover  13 . The long tube  60  can thus readily be plugged into the second insertion bore of the support plate  35  and the second insertion bore  61  of the cover  13 . In that case, the other insertion bore  52  of the support plate  35  is closed off by a screw  55 . For the flow path between the gear pump  65  and the other connecting cap on the cover  13 , a connecting flange  66  is used in which the insertion bore  67  lies on the other side from the delivery connection of the gear pump  65 , as is clearly apparent from FIG.  3 . Apart from the two different connecting flanges  66 , therefore, no different parts are necessary in order to produce the two alternative embodiments, either that according to FIGS. 1 and 2 or that according to FIG.  3 . 
     In the embodiment shown in FIG. 5, two gear pumps  65  are driven via the drive shaft  23  of the electric motor  11 , these being arranged axially in series and fixed on a support plate  75  which, in exactly the same way as the support plate  35  of the embodiment according to FIG. 1, is fixed on the housing mid-section  14 . The support plate  75  is thinner in the axial direction than the support plate  35 , as it comprises neither ducts for the pressure medium flow nor a seating for a bearing. The two covers  12  and  13 , of which only the cover  13  is shown in FIG. 5, are the same as in the first example of embodiment. The housing mid-section may have a different length from that in the first example of embodiment. The flow path from the delivery connection of the gear pump  65  nearer to the cover  13  to the second connecting cap  45  of the cover  13  is identical to the corresponding flow path of the gear pump  65  of the first example of embodiment. Again, the short tube  68  lies within it and is plugged axially into an insertion bore  67  of a connecting flange  66  and into the second insertion bore  61  of the cap  13 . The connecting flange  66 , which has also been used for the version of the first example of embodiment shown in FIG. 3, is fixed to the delivery connection of the gear pump  65  seated directly on the support plate  75 . In the case of this connecting flange, the insertion bore  67  open toward the cover  13  lies on the other side of the delivery connection of the gear pump. Between the connecting flange and the first insertion bore  61  of the cover  13  extends a long, straight tube  60  which, exactly as in the first embodiment, is machined at its ends and is pressed against the connecting flange  66  by an O-ring  64  with interposed compensating disks  62  and shim  63 . In operation, therefore, one gear pump  65  pumps to the first connecting cap and the other gear pump  65  to the second connecting cap  45  of the cover  13 . 
     The example of embodiment shown in FIG. 6 differs from that shown in FIG. 5 primarily in that it comprises not two gear pumps  65  but only one. Accordingly, the housing mid-section  14  of the embodiment according to FIG. 6 is shorter than in the embodiment according to FIG.  5 . The support plate is the same as in the embodiment according to FIG. 5 and, as in that case and as in the embodiment according to FIG. 1, is fixed to the housing mid-section  14  by screws  36 . The gear pump  65  pumps via a connecting flange  66 , a short, axially extending and plugged-in tube  68  and ducts in the cover  13  to the first or second connecting cap  45 , depending on which connecting flange  66  is used. A closure screw is screwed into the delivery aperture of the other connecting cap. 
     In the embodiment according to FIG. 7, again, a thicker support plate  80  is present than in the two embodiments according to FIGS. 5 and 6, in which support plate  80  a ducting system for a pressure medium flow is provided. On the side of the support plate  80  facing the electric motor  11 , as in the embodiment according to FIG. 1, conveying units  41  of a radial piston pump  40  are retained with the aid of an annular disk  42  and with the aid of screws  43 . A single axial insertion bore  52  opens into the ducting system of the support plate  80 , into which insertion bore  52  is plugged a tube  81 , extending axially and machined at both its ends, and having, by comparison with the tubes  60 , a short clear distance to bridge between the support plate  80  and the cover  13 . The axial insertion bore  82  present in the cap  13  for the tube  81  is provided with a thread within a section located upstream of the end face of the tube  81  and opens into a bore  83  tilted slightly out of the plane of the cover  13  and leading to one of two connecting sockets  45 . The tube  81 , also, is pressed against the support plate  80  by an O-ring  64  with the interposition of a shim  63 . 
     The support plate  80  in the example of embodiment according to FIG. 7 is retained not on the housing mid-section  14  but, with the interposition of a plurality of conveying units  41  of a second radial piston pump  85 , on the cover  13  by means of machine screws  36 . The conveying units  41  are clamped between the cover  13  and the support plate  80 . In addition, they are secured by threaded bolts  86  driven into the cover  13  and guiding them laterally. Furthermore, of course, the housings  46  of the pressure valves  44  of the conveying units  41  of the second radial piston pump  85  also contribute to the mounting of the conveying units. The conveying units of the second radial piston pump  85  convey pressure medium into a ducting system of the cover  13 , which comprises a bore (not shown in detail) which leads to the second connecting cap  45  (likewise not shown in detail). The bore  83  apparent from FIG. 7 also opens into the ducting system of the second radial piston pump  85  at a distance from the axial bore  82 . As is apparent from FIG. 7, however, a closure screw  87  is driven into the section of the bore  83  which is located between the axial bore  82  and the ducting system of the radial piston pump  85 , so that separate pressurized flow paths are present for the two radial piston pumps  40  and  85 , the radial piston pump  40  pumping to the connecting cap  45  identifiable in FIG.  7  and the radial piston pump  85  to the other connecting cap  45 . In an alternative version of the embodiment according to FIG. 7, the screw  87  may be absent and the delivery aperture of the second connecting cap  45  closed off. In this case, both radial piston pumps pump to the connecting cap  45  visible in FIG.  7 . 
     In the compact unit shown in FIG. 8, a plurality of conveying units  41  of a radial piston pump  85  are fixed on the cover  13  by means of an annular disk  42  and by means of screws  43 . A support plate, located entirely within the housing, for a pump or for individual conveying units of a pump is not present. The cover  13  is identical with the cover of the embodiment according to FIG.  7 . However, a closure screw  89  is driven into the threaded section of the axial insertion bore  82 , whereas the closure screw  87  is absent. The conveying units  41  thus pump via the bore  83  to the delivery aperture  88  of one connecting cap  45 . The closure screw  89  prevents a short circuit within the housing  10 . The unit according to FIG. 8 thus again expresses the inventive idea of providing, irrespective of the actual specification of a hydraulic compact unit, the delivery connection for the one or more pumps in the cover  13  in each case. 
     It should also be pointed out that, in the two embodiments according to FIGS. 7 and 8, a long motor shaft  23  is mounted in a roller bearing  51  received by the cover  13 . Each cam  49  is shrunk onto the motor shaft  23 .