Abstract:
A three-side stacker with a side push frame at one end of the stacker, on which a side arm is horizontally traversable mounted, wherein the side arm has a first traversable portion mounted on the side push frame and a second portion, which is mounted pivotally around a vertical axis on the first portion and on which a load supporting means is mounted, which is actuable by a hydraulic lifting cylinder, and a pivoting equipment for the second portion, mounted on the first portion, wherein the casing of a hydraulic rotational drive with a rotatable spindle is fixed on the first portion, wherein a portion of the spindle is splinedly connected with a holder or a lifting scaffold for the load supporting means outside the casing.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   Not applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
   Not applicable. 
   BACKGROUND OF THE INVENTION 
   Such a three-side stacker has become known from U.S. Pat. No. 4,470,750, the entire contents of which are hereby incorporated by reference in its entirety, for instance. For instance, it is used as a storage rack conveyor. A side push or guide frame is arranged on the front end, transversely to the longitudinal axis of the apparatus. Depending on the type, the side push frame is connected stationarily with the vehicle or guided in the height on a lifting mast or so. Finally, it is also possible to fix the side push frame on the front side of the cab of the vehicle, which is itself as a whole traversable in the height on the lifting mast. In this case, the three-side stacker represents an order picking apparatus. A side arm is horizontally traversable on the side push frame. The side arm consists of two portions, namely a first portion, which is guided on the side push frame, and a second portion, which is mounted to be rotatable around a vertical axis. On the second portion, there is either directly attached a holder for a load supporting means, a fork for instance, or an additional mast, for instance, on which the fork holder can be traversed in the height. With the aid of a drive, which is preferably a hydraulic one, the second portion and with this the load fork or the mast, respectively, can be pivoted around a vertical axis in an angle range of 0 to 180°. The pivoting drive has parallel hydraulic cylinders, which actuate a chain, which is turn wound around a sprocket. The sprocket is splinedly connected with a shaft portion, which is mounted in a rotational bearing of the side arm and is connected with a lifting scaffold. The hydraulic lines for the supply of the drives on the movable parts are integrated and guided in a suitable manner, such that they can follow the horizontal and rotational movement of the side arm or the lifting scaffold, respectively. Toothed racks, arranged parallel in a distance and running horizontally, are attached on the side push frame, with which sprockets or gearwheels on the side arm co-operate. The sprockets or gearwheels sit splinedly on a common torsion shaft, which is in turn driven by a suitable drive. With the aid of this drive, the side arm can be moved horizontally. The torsion shaft provides also stabilisation around an axis parallel to the longitudinal axis of the vehicle. 
   The rotational drive for the holder for a load receiving means or a mast on the side arm of the side push frame, respectively, requires a high expense for assembly and maintenance, as well as a big number of individual components. In addition, the drive needs a relatively large installation space. 
   The present invention is based on the objective to improve a three-side stacker of the type mentioned in the beginning, such that the drive for a lifting scaffold or a holder for a load receiving means on the side arm of the side push frame, respectively, needs a smaller number of individual components and requires less expense in the assembly. 
   BRIEF SUMMARY OF THE INVENTION 
   In the present invention, the casing of a hydraulic rotational drive is fixed on the first portion of the side arm. The hydraulic rotational drive has a lathe spindle, which stays outside the casing with a portion on which a holder or a lifting scaffold for the load supporting means is splinedly attached. The casing can be attached without problems on that arm of the side arm which is coupled to the side push frame. It is only required to provide the outside positioned portion of the lathe spindle of the hydraulic rotational drive with means for attaching the pivoting body thereon, which is pivotable about an angle of approximately 180°, according to the principle of the three-side reach truck. In the case that the body has a lifting scaffold and also a lifting cylinder for the actuation of the load supporting means along the lifting scaffold, care must also be taken for a hydraulic supply of the lifting cylinder. 
   According to an embodiment of the present invention, it is provided for this purpose that the rotational drive is realised as a rotary transmission leadthrough for the line of the hydraulic medium towards the lifting cylinder and away from the same, wherein an axial channel in the spindle is in every position of the spindle connected with a stationary hook-up on the casing for the hydraulic medium, and the axial channel is connected with the lifting cylinder. Such a supply of the hydraulic medium avoids the use of a hydraulic tube. As is known, movable tubes are a source of troubles and errors, in particular when the actuated part performs a turning or swivelling movement, respectively. 
   In a further embodiment of the idea pointed out before, the present invention provides that the spindle of the rotational drive is actuable by a threaded sleeve, which is in turn actuable by a plunger which is guided in the casing of the rotational drive. The channel in the spindle is connected with at least one radial channel in a flange of the spindle, which is sealingly and rotatably mounted in the casing, wherein the radial channel is aligned with an annular channel on the inner side of the casing, which is in connection with the outer hook-up for the hydraulic medium on the outer side of the casing via bore portions. A hydraulic drive of the described kind is per se known. It is only slightly modified so that it can be used as a rotational drive for the pivotable lifting scaffold of a three-side stacker, for instance. 
   In another embodiment of the present invention, it is provided that a bottom part for the lifting cylinder is connected with the free end of the spindle, on which the envelope of the lifting cylinder is sealingly supported. 
   In the drive equipment according to the invention for the load supporting means or the lifting scaffold of a three-side stacker, respectively, it is advantageous when the respective turning position can be determined. As a consequence, one embodiment of the present invention provides that a transmitter is connected with the spindle, and an angle sensor is arranged in the casing. Different mechanical or contactless arrangements of sensor and transmitter are conceivable. According to a further embodiment of the present invention, a particularly simple measure is that a gearwheel sits on the spindle, which meshes with a sprocket of a potentiometer. 
   Several advantages are attained by the present invention. The installation frame for the pivoting drive is extremely small and permits to place the side push frame further downward, through which the visible edge is moved towards the downside and thus it improves the sight on the fork arms. Even in the horizontal direction, a reduction of the installation space is possible. The assembly and the maintenance are improved with respect to conventional drives, not at least by the reduction of the number of the individual parts. A very important advantage is that the force which is exerted by the mast or the load supporting means is directly taken up by the spindle. Through this, the rotational drive is not only a driving means but also a force receiving means. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     The present invention is explained in more detail by means of drawings below. 
       FIG. 1  shows a side push frame with side arm for a three-side stacker according to the invention in a perspective view. 
       FIG. 2  shows a final view of the representation according to  FIG. 1 . 
       FIG. 3  shows schematically a rotational drive for the arrangement according to  FIGS. 1 and 2  in a cross section. 
       FIG. 4  shows a perspective view of the side push frame with side arm for a three-side stacker shown in  FIG. 1 . 
       FIG. 5  shows a perspective view of the side push frame with side arm shown in  FIG. 4  with the fork rotated 90 degrees. 
       FIG. 6  shows a cross-sectional view of the embodiment shown in  FIG. 4 . 
       FIG. 7  shows a cross-sectional view of the embodiment shown in  FIG. 5 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While this invention may be embodied in many different forms, there are described in detail herein a specific preferred embodiment of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiment illustrated 
   In the  FIGS. 1 and 2 , a side push frame  10  of a three-side stacker is designated with  10 . The three-side stacker is not shown for the rest. Insofar, reference is made to U.S. Pat. No. 4,470,750, for instance. The side push frame  10  is fixed horizontally on the front side of the three-side stacker, for instance on the vehicle itself or on a lifting mast or even on a cab, which is height-movably guided on the lifting mast. 
   The side push frame has a frame profile  12 , U-shaped in its cross section, through which a channel  14  is formed. On the upper side of the frame profile  12 , a flat rail  16  is fixed. A toothed rack  18  is fixed on the rail  16 . Rail  16  and toothed rack  18  run horizontally. A further flat rail is fixed on the lower side of the frame profile  12 . A toothed rack  22  is fixed on the rail  20 . The toothing of the toothed rack  22  does not extend completely over the width of the rack, instead a slightly retracted portion  24  is provided, which a forms a horizontally extending vertical running path  26 . On the side directed towards the toothing of the toothed rack  18 , the rail  16  forms also a running path  28 . This one too is somewhat retracted against the toothing of the toothed rack  18 . The running paths  26 ,  28  extend in a common plane. However, they can also be in parallel planes. In addition, they run in parallel to the parallel toothed racks  18 ,  22 . 
   A side arm  30 , generally extending vertically to the frame profile  12 , has an upper mounting plate  32  and a lower mounting plate  34 , which are fixed on a stable casing, which is indicated at  36 . The mounting plates  32 ,  34  rotatably bear a torsion shaft  38 , on which an upper gearwheel  40  and a lower gearwheel  42  are splinedly arranged. The gearwheels  40 ,  42  mesh with the toothing of the toothed racks  18 ,  22 . The torsion shaft  38  is rotationally driven by a hydraulic drive  46 . On the mounting plate  32 , two guide rollers are rotatably mounted around a vertical axis on the lower side, one of which can be recognised at  50  in  FIG. 2 . The guide rollers  50  co-operate with a guideway of the toothed rack  18 , which is on the rear side in  FIG. 1 . On the lower mounting plate  34 , two guide rollers are also rotatably mounted, one of which is shown in  FIG. 2  at  52 . They co-operate with a guideway on the backside ( FIG. 1 ) of the toothed rack  22 . The guide rollers  50 ,  52  take up the weight momentum of the side arm  30  around an axis parallel to the longitudinal axis of the side push frame  10 . 
   In the mounting plate  32 , a further guide roller  54  is rotatably mounted around a horizontal axis. It co-operates with an upper guideway of the toothed rack  18  and takes up the weight force of the side arm. Preferably, two such rolls can also be provided. 
   An arm  58  is fixed on the casing  36  of the side arm  30 , extending horizontally on the lower end, on which a further mounting plate  60  is fixed, which extends transversely. The mounting plate  60  carries a hydraulic rotational drive  66  via an upper arm  62  or a lower arm  64 . Via a block  68 , its casing supports a lifting mast  70 , into which a lifting cylinder  72  is inserted, which is in turn supported on the block  68 . With the aid of the rotational drive  66 , the lifting mast  70  can be turned around a vertical axis  72   a , preferably between 0 and 180° or 0 to ±90°. On the lifting mast  70 , a sliding cradle or fork carrier  76  is guided in the height, which can be shifted in the height with the aid of a not shown chain and the lifting cylinder  72 . Such a lifting drive is commonly known in floor conveyors, and thus it will not be described in more detail. In  FIG. 1  or  2 , a mounting for a sensor is indicated at  78 , by which the lifting height of the sliding cradle  76  is determined. 
   The supply of hydraulic energy for the drives  46 ,  66  and the cylinder  72  has naturally to take place from the carrier vehicle, wherein the hydraulic lines are integrated in a corresponding manner (not shown) and are guided through the profile frame  12 . They can be guided in a loop (not shown), which is moved in the channel  14 , so that the side arm  30  can freely move along the side push frame  10 . 
   As can be further recognised in  FIGS. 1 and 2 , an upper spacer roller  86  and a lower spacer roller  88  sit on the torsion shaft  38 . The spacer roller  86  rolls on a guideway  26 ,  28 . With the aid of the spacer rollers  86 ,  88 , a predetermined distance between the gearwheels  40 ,  42  and the toothed racks  18 ,  22  is set. 
   In  FIG. 3 , the hydraulic rotational drive  66  is shown in some more detail. One recognises a casing  100 , which is connected via the lugs  62 ,  64  with the mounting plate  60 , as has already been described. The casing mounts a spindle  101 , which consists of the portions  102 ,  104 ,  106 ,  108 ,  110  and  112 . The mentioned portions are either part of a workpiece formed in one part or splinedly connected with each other. A flange  114  is connected with the lower portion  102 , which has not shown seals which co-operate with a casing bore  116 . The portion  106 , provided with a greater radial diameter, is axially mounted in the casing  100  with the aid of an upper and a lower nail bearing  118 ,  120 , so that the spindle is rotatable, but axially stationary. In the casing bore  116 , a threaded sleeve  122  is arranged, which is provided with a not shown inner and outer thread, which threads are realised as being relatively steep. The inner thread of the threaded sleeve co-operates with an outer thread (not shown) of the portion  104 , and the outer thread of the threaded sleeve  122  co-operates with a thread in the bore  116 , wherein the threads are directed contrarily on radially opposing sides of the sleeve. Further, a plunger  124  is connected with the threaded sleeve  122 , which can be pressurized with hydraulic fluid from opposing sides. The hydraulic fluid is fed via hook-ups  126  and  128  ( FIG. 2 ). The lines to the hook-ups  126  and  128  are not shown. As a consequence, the plunger  124  moves in the axial direction upon pressurization, and thus the linear motion of the plunger  124  is transformed into a rotational movement by the threaded sleeve and the spindle. Such a drive is in principle known. Through the co-operation of two pairs of threads, it is possible to produce the desired rotational movement about an angle of 180° and more with a relatively small stroke. 
   As can be seen from  FIG. 2 , the casing of the rotational drive  66  has an additional hook-up  130  for hydraulic medium. It is connected with a first bore portion  132  in the casing  100 , which is connected with an axis parallel bore portion  134 . The vertical axis parallel bore portion  134  is in connection with an annular groove  136  on the inner side of the casing  100 . Several radially or beam-shaped, respectively, channels  138  run out into the annular groove  136 . The channels  138  run out into an axial channel  140 , which extends towards the upside through all the portions of the spindle  101  up to portion  112  inclusively. Towards the downside, the axial channel  140  is closed by a stopper  142 . Through this, a rotary transmission leadthrough is provided. The hydraulic medium reaches the rotating spindle from the stationary hook-up  130 . 
   The spindle portion  110  forms a bottom part for the lifting cylinder  72 , wherein the portion  112 , which is smaller in its diameter, is sealingly inserted into the envelope of the cylinder  72 . The ring  69  ( FIG. 2 ) is screwed on the outer thread of portion  110  and thus it fastens the block  68  on the conical portion  108 . The mast  70  is fixed on the block  68 . The hydraulic medium is directly introduced into the lifting cylinder  72 . The spindle portion  108 , conical in its upper region and thereafter cylindrical, carries the lifting mast  70 , which is not shown in more detail in  FIG. 3 . 
   As a consequence, when the hydraulic rotational drive according to  FIG. 3  is actuated, the spindle  101  and with it lifting mast  70  and lifting cylinder  72  are rotated about a desired amount around the vertical axis  72   a . Stops which limit the rotation are internally present in the rotational drive and therefore they have not to be provided separately. 
   With the lower side of the flange  114 , a gearwheel  144  is splinedly connected, which meshes with a sprocket (not shown) which drives a not shown potentiometer. Thus, the respective turning position of the lifting mast  70  or the lifting cylinder  72  can be determined with the aid of such an arrangement. 
     FIGS. 4 and 5  each show a perspective view of an embodiment of the invention as shown in  FIG. 1 .  FIG. 5  shows the fork carrier  76  rotated 90 degrees from its position in  FIG. 4 .  FIGS. 6 and 7  show a cross sectional view of the embodiment as shown in  FIGS. 4 and 5 , respectively. Here, the actuation of mast  70  as described above can be seen. The sleeve  122  has an inner and outer thread. The outer thread engages a thread of the casing bore  116 , and the inner thread engages a thread of spindle  101 . The spindle  101  through portion  112  engages a member  68 , which in turn is rotationally fixed with respect to mast  70 . A plunger  124  is connected with sleeve  122 . If plunger  124  is moved upwardly or downwardly, the sleeve is rotated accordingly and drives spindle  101  rotationally. Thus, mast  70  is rotated as desired. This is described in the specification at pages 7-8, and no new matter has been introduced. 
   The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
   Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below. 
   This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.