Abstract:
A stop unit comprising: a guiding device which can be mounted to an overhead conveyor; a carriage having an abutting section, wherein the carriage is movably supported by the guiding device along a transverse direction which is orientated transversely relative to a longitudinal direction; and a drive which is coupled to the carriage and which is configured to extract, during activation, the carriage from a release position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of the German patent application DE 10 2011 119 411.1, entitled “Stopper-Einheit für Klinkenförderer” and filed on Nov. 21, 2011, which German patent application is incorporated herewith by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a stop unit (which can also be installed later) of an overhead conveyor which transports a clip driver downstream in a slot of a supporting rail, on which supporting rail hangers are slidingly transported by means of the clip drivers, the slot being open at least at one side and the conveying direction being orientated in parallel relative a longitudinal direction of the supporting rail. The invention further relates to a corresponding overhead conveyor including the stop unit. 
       RELATED PRIOR ART 
       [0003]    Clip drivers of clip conveyors are generally disclosed in the documents DE 299 15 523 U1 and DE 298 09 909 U1. With clip conveyors hanging products such as garments on coat hangers are conveyed by means of transportation hooks on sliding rails and by means of traction members, which are guided above the sliding rail, wherein a plurality of hanging clips are pivotally mounted to the traction member at distances. As a rule, conveyors of this type comprise traction members in terms of endless chains, wherein the individual clips are attached to the traction members in distances. The clips are pivotally attached to the chain so that they hang and drive the individual transportation hooks (hangers) by means of the driver hooks thereof. For example, transportation hooks of this type are the hooks of coat hangers which are frequently used as means for transporting garments in the textile industry. 
         [0004]    The German utility model DE 203 11 926 U1 discloses an overhead conveyor system. Also in this case a clip is supported pivotally around a downstream axis relative to a carrier, which is connected to the overhead conveyor, wherein a driver hook is pivotally connected to an upstream end, the driver hook being biased in the conveying direction by means of a traction spring. Again, a conveying chain is used as a traction member. The conveying chain carries clip drivers at its bottom side. Each of the clip drivers comprises a carrier, to which carrier a clip is pivotally attached by means of a joint, namely at the downstream end of the clip, i.e. the carrier. The clip comprises—at an upstream end relative to the conveying direction—one driver hook which points downwardly to the conveying rail. A downstream recess, relative to the conveying direction, is located in the clip opposite relative to the hook. A switching cam, which is again located downstream relative to this recess, is provided in terms of an area, which is formed at a bottom side of the clip and which is curved downwardly. At one location of the conveying rail, which can be chosen arbitrarily, a so-called clip opener can be provided. Connected hangers can be released from the clips by means of the clip opener. Released hangers are accumulated at the location of the clip opener. The conveying rail comprises a recess which is open upwardly, in which recess an opening lever is supported pivotally having two arms. In a resting position, the opening lever is located within the recess so that connected hangers can pass unhinderedly. In an operating position, the opening lever is pivoted out of the recess. Then, the switching cam of an approaching clip contacts a front part of the opening lever, which has been pivoted to the outside. Thereby, the clip is pivoted upwardly, i.e. is pivoted away from the conveying rail. In this manner the hanger is released. 
         [0005]    Such clips have a so-called “power-and-free functionality”. As a rule, each of the clips conveys one hanger. However, sometimes also a number of hangers is conveyed. 
         [0006]    The opener (stop device), as described above, is disadvantageous in that a designer already needs to determine during the planning phase the location where the stop device is to be positioned later, in order to integrate the stop device. Transferring or placing the stop device at a later time is very time-consuming. Installation of additional stop devices “on site” requires many efforts. The conveying rail needs to be opened by using a saw, and additional supporting devices need to be attached. For integrating an opening lever into the bottom of the rail, holes or slots need to be inserted into the conveying rail from above. Hooks of hangers can be caught in these holes or slots. This can result in an undesired stop, or even damage. 
         [0007]    The document DE 196 14 905 A1 discloses a conveying bag for use in an overhead conveyor system including a discharge station. The document DE 90 03 011 U1 discloses a station for separating coat hangers. The document DE 103 17 742 B3 discloses an accumulation section of an overhead conveyor system including clip drivers. 
       SUMMARY OF THE INVENTION 
       [0008]    Therefore, it is an object of the present invention to provide an improved stop unit which can also be installed later. 
         [0009]    This object is generally solved by a stop unit of an overhead conveyor transporting clip drivers in a slot of a supporting rail, the slot being open on at least one side, wherein hangers are slidingly transported by means of the clip drivers downstream along a conveying direction which is orientated in parallel relative to a longitudinal direction of the supporting rail, comprising: a guiding device which can be mounted to the overhead conveyor; a carriage having an abutting section, wherein the carriage is movably supported, preferably linearly, by means of the guiding device along a transverse direction which is orientated across the longitudinal direction; and a drive which is coupled to the carriage and which is configured to extend, during activation, the carriage from a release position, in which position the abutting section of the carriage does not project over the supporting rail so that the hangers can pass the carriage, to a stop position along the transverse direction, in which stop position the abutting section projects over the supporting rail, preferably over an entire width thereof; wherein the carriage, if the drive is activated, can be retracted to the release position in case of an action of force along the transverse direction in case and rests in a current position thereof in case of an action of force which is only exerted along the longitudinal direction. The stop unit can be installed later in the overhead conveyor system, the system comprising the supporting rail, clip drivers and hangers. 
         [0010]    According to another aspect of the invention it is disclosed a stop unit for use in an overhead conveyor system comprising clip drivers, a supporting rail and hangers, which clip drivers are transported in a slot of the supporting rail, the slot being open at at least one side of the supporting rail, wherein the hangers are slidingly transported downstream by means of the clip drivers along a conveying direction which is orientated in parallel relative to a longitudinal direction of the supporting rail, the stop unit comprising: a guiding device which is mountable to the overhead conveyor; a carriage having an abutting section, wherein the carriage is movably supported, preferably linearly, by means of the guiding device along a transverse direction, which is orientated transversely to the longitudinal direction; and a drive which is coupled to the carriage, which drive is configured to drive, during its activation, the carriage from a release position, in which release position the abutting section of the carriage does not project over the supporting rail so that the hangers can pass the carriage without colliding therewith, to a stop position along the transverse direction, in which stop position the abutting section projects over an entire width of the supporting rail, preferably over an entire width thereof such that the hangers are released and accumulated by the abutting section while the clip drivers are continuously moved downstream; wherein the carriage, in an activated state of if the drive, is retractable to the release position in case of an action of force along the transverse direction, and rests in a current position in case of an action of force which is only exerted along the longitudinal direction. 
         [0011]    The stop unit of the invention can be installed later. The stop unit can be mounted laterally without cutting the supporting rail by using a saw or disassembling same. The stop unit can be installed an arbitrarily location of the conveying path. The stop unit has a two-stage configuration, wherein a first stage of the carriage is spring biased. If the carriage hits a hanger or even a clip during extension, at maximum only a small force of the spring device is applied to the hanger or the clip. Damages are prevented. As soon as the obstacle (hanger/clip) passes by, a second stage of the carriage applies. The carriage is completely extended between the clips and hangers. The carriage, in this position, stops the other clips, and the hangers are accumulated in front of the carriage. 
         [0012]    However, if the carriage hits one of the hangers, the hanger will still be transported by the engaging clip and will not be released randomly. 
         [0013]    The transport rail is not interrupted and does not require additional holes or slots for mounting the stop unit, in which holes or slots the hangers or the hooks could get caught. 
         [0014]    The stop unit can be mounted at any place and at any time, or even later. The stop unit is absolutely fault tolerant. It can be manufactured in a simple and cost-efficient manner. It does not exist any undefined state if the carriage is activated and then hits one of the hangers or clips. 
         [0015]    In accordance with a preferred embodiment the abutting section comprises a first front face at a free end which is orientated towards the supporting rail, wherein the first front face is orientated obliquely relative to the longitudinal direction of the supporting rail, so that the free end defines a tip at an upstream location. 
         [0016]    The obliquely orientated first front face is required for an introduction of force in case of the carriage hitting one of the clips or hangers just passing the stop unit, during the activation thereof. In this instance, a retracting force is introduced by the hanger itself, in order to prevent damage of the system. 
         [0017]    Further, it is advantageous if the abutting section comprises a second front face being orientated in parallel relative to the longitudinal direction and which follows the first front face in an upstream direction, wherein the second front face defines the tip. 
         [0018]    The second (parallel) front face can contact the clip in a planar manner, and guides the clip around the carriage until the hanger reaches the first oblique face. Also in this manner damages are prevented. 
         [0019]    With another preferred embodiment the stop unit further comprises a spring device arranged between the carriage and the drive so that the carriage, in an activated state, can be returned to the release position, wherein the carriage preferably comprises a spring-contact section. 
         [0020]    The spring device absorbs the force which is exerted by the drive, during a change of the carriage from the release position to the stop position, to the carriage although the carriage cannot be extended completely over the entire width of the supporting rail due to a clip driver which is in the way. Damage of the stop unit is prevented in this manner. 
         [0021]    Further it is preferred: that the drive comprises a cylinder having a piston rod, that the piston rod is connected to a connecting element, that the connecting element is connected to a shaft which is supported in a freely movable manner in an opening of the carriage, and that the spring device is arranged between the carriage and the connecting element. 
         [0022]    The stop unit is positioned laterally relative to the supporting rail and, therefore, can be accessed well for the sake of installation and maintenance. The previously known switches or openers were integrated into the supporting rail and could not be accessed or maintained conveniently. 
         [0023]    Further, it is advantageous if the stop unit further comprises: a supporting-rail elevation which is connectable to the supporting rail and formed such that height of an intermediate space between the supporting rail and the carriage, which projects over the supporting rail in the stop position, reduces in a downstream direction such that a hanger, which is not in engagement with one of the drivers, can penetrate the intermediate space, but cannot pass the intermediate space in a downstream direction. 
         [0024]    By this measure, hangers having different (wire) hook thicknesses can be handled without prone to failure. 
         [0025]    With another preferred embodiment the supporting-rail elevation is adapted to a shape of the supporting rail such that the supporting-rail elevation replaces part of the supporting rail, can be clipped to the supporting rail from the outside, or can be fixed thereto. 
         [0026]    The supporting rail does not need to be cut by using a saw, or to be manipulated otherwise, for mounting the stop unit. The supporting-rail elevation is simply clipped-on from the outside and fixed to an arbitrary location. Mounting is simple and fast. 
         [0027]    With another advantageous embodiment the supporting-rail elevation comprises a rise which projects over a sliding area of the supporting rail, and which preferably comprises an increasing flank, a plateau extending in parallel relative to the sliding area, as well as a decreasing flank. 
         [0028]    Further it is advantageous if each of the hangers comprises a hanger head which, in a state when the hanger is slidingly transported on the supporting rail, comprises a cross section, which is preferably round, having a center in a plane perpendicular relative to the transverse direction, and wherein a bottom side of the abutting section is arranged in a height, relative to a sliding area of the supporting rail, which is greater than a height of the center relative to the sliding area. 
         [0029]    This arrangement ensures that an engaged hanger is pulled below the stopper for further downstream acting on the stopper such that the clips can pass the stop unit without damaging same. 
         [0030]    It is additionally preferred if the carriage further comprises a guiding section, wherein the guiding device comprises a rail for guiding the carriage which is configured such that the guiding section of the carriage slides in the rail along the transverse direction for guiding the carriage, preferably in terms of a positive engagement. 
         [0031]    With a particular embodiment the drive comprises a housing. 
         [0032]    Further, it is preferred that the sliding area of the supporting rail and a bottom side of the abutting section are arranged in two planes which are distanced and arranged in parallel to each other. 
         [0033]    With another embodiment the abutting section can be deflected flexibly in height relative to one of the clip drivers, which engages one of the hangers and just passes the stop unit, during movement to the stop position, thereby allowing the engaged hanger to move below the abutting section with regard to the conveying direction. 
         [0034]    It is clear that the above-mentioned and hereinafter still to be explained features cannot only be used in the respectively given combination but also in other combinations or alone without departing from the scope of the present invention. 
         [0035]    Embodiments of the invention are illustrated in the figures and will be explained in more detail in the description below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]      FIGS. 1A-1C  show different views of an overhead conveyor in accordance with the invention; 
           [0037]      FIGS. 2A-2C  respectively show different views of different moments during a stopping process of the stop unit in accordance with the  FIG. 1 ; 
           [0038]      FIGS. 3A-3E  show different side views of the stop unit of  FIG. 1  at different magnifications; 
           [0039]      FIGS. 4A-4B  show top views of the stop unit of  FIG. 1  for illustrating the situation of  FIG. 2B ; and 
           [0040]      FIG. 5  shows a top view of a modified carriage. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0041]    With reference to the  FIGS. 1A-1C  the structure of a stop unit  30  in accordance with the invention will be described below, the stop unit  30  being used with an overhead conveyor or in a conveyor system  10 , wherein the description will be presented under common reference to all views of the  FIGS. 1A-1C .  FIG. 1A  shows a front view along a longitudinal direction X, in a partial sectional view, on the overhead conveyor  10 .  FIG. 1B  shows a side view of the overhead conveyor  10 , and  FIG. 1C  shows a perspective view of the overhead conveyor  10  of  FIGS. 1A and 1B . 
         [0042]    Hangers  12  are transported in a sliding manner on a supporting rail  16  by means of the overhead conveyor  10  by means of clip drivers  14 . The supporting rail  16  is open upwardly (to one side) for allowing receiving the clip drivers  14 , at least partially, therein and guiding same in the longitudinal direction X. It is clear that arbitrary courses of curves including increases and decreases can be represented by means of the supporting rail  16 , which is exemplarily shown as a straight line. For the sake of a simplified description the supporting rail  16 , in the present case, is represented only as a straight line and in a horizontal attitude. The hangers  12  are sitting with their hooks  18  at two points on the supporting rail  16 , having, for example, an U-shaped cross section. It is clear that with other shapes of cross section more or less contact points will be present at the hook  18 , which is laterally open in a downward direction and which preferably has the round shape. 
         [0043]    The supporting rail  16  is carried—typically over head—by means of a supporting section  20 . The supporting section  20  can have one or more notches  22  ( FIG. 1A ) in side areas thereof for attaching additional components of the overhead conveyor  10 . For example, U-shaped guiding sections  24 , which are open downwardly, are inserted into the lateral notches  22  of the supporting section  20 . The cross sectional shape of the guiding section  24  can be selected arbitrarily, and can be adapted preferably to the cross section of a traction member such as a conveying chain. In the guiding section  24 - 2  ( FIG. 1A ), illustrated at the right, a run of an endlessly circulating conveying chain is shown, which is connected to the clip drivers  14 . 
         [0044]    The supporting section  20  can comprise a connecting element  26  having an L-shape, the connecting element  26  supporting the supporting rail  16 . It is clear that the connecting element  26  can be provided merely in a distributed manner, across the length of a conveyor track, and does not need to extend over the entire length of the supporting rail  16 , which is typically formed continuously. 
         [0045]    The stop unit  30  of the invention will be described below. The stop unit  30  can comprise one supporting element  32  (e.g., a rail, section, etc.), which can be Z-shaped, by which supporting elements  32  a guiding device  34  is fixed laterally to the supporting rail  16  on the supporting section  20 . For example, the supporting element  32  can be fixed in the notch  22  in the top side of the supporting section  20 . The supporting element  32  is preferably designed such that the guiding device  34  is arranged at a level of the hanger  12  in the clip driver  14 , where the clip driver  14  grabs the hook  18  of the hanger  12  and, in a normal state, picks up same. In the example of  FIG. 1A  the guiding device  34  is provided at a bottom side of a horizontal leg of the supporting element  32 , the leg being turned away from the supporting section  20 . A horizontal leg  32 - 2  of the supporting element  32 , facing the supporting section  20 , is connected to the turned-away leg of the supporting element  32  via a vertical leg  32 - 1 . 
         [0046]    The guiding device  34  serves for receiving a supported carriage  36  ( FIG. 1A ), which is movable horizontally and transversely relative to the longitudinal direction X. The carriage  34  can be received in and guided by a carriage-guiding rail  35 . The receipt can be achieved by positive engagement. The carriage  36 , in the front view of  FIG. 1A , has, for example, an L-shape with a short vertical leg and a longer horizontal leg, i.e. a stopper  46 . 
         [0047]    The carriage  36  can be extended transversely by means of a drive  38  at a level of a vertex of the hooks  18 , in this case along the direction Z, at a small distance completely across the supporting rail  16 , as will be described in more detail with reference to  FIG. 2C  below. In  FIG. 1A  and  FIG. 2A  a release position of the stop unit  30  is respectively shown, in which release position the carriage is retracted so far relative to the supporting rail  16  that the clip driver  14 , particularly if hangers  12  are engaged, can pass without any collision. Movability of the carriage  36  is indicated in  FIG. 1A  by means of a double arrow  40  extending in parallel relative to the direction Z, which is thus oriented perpendicular relative to the longitudinal direction X. The perpendicular orientation is preferred in particular. The carriage  36 , however, can also be slightly moved obliquely relative to the supporting rail  16 , for example, at an angle between 70° and 89° (in the plane XZ). The guidance of the carriage  36  is taken over by the carriage-guiding rail  35 , which is adapted to receive forces and forward same to the supporting section  20 , the forces being orientated perpendicular relative to actuating direction  40  of the carriage  36 . 
         [0048]    The drive  38  can be positioned above the carriage-guiding rail  35  and the carriage  36 , for example, in a region of the vertical leg  32 - 1  and the horizontal leg of the supporting element  32 , which is turned away. A spring device  42  is provided between the drive  38  and the carriage  36 . In  FIG. 1 , for example, a spiral spring  44  is shown, which extends around a shaft  45  having a shape of a cylinder, wherein the shaft  45  can penetrate through the carriage  36  via an opening  89  (upper part of  FIG. 2B ) in the vertical leg of the carriage  36 . The shaft  45 , which is orientated horizontally, is fixedly connected to a vertically arranged connecting element  48 . The connecting element  48 , in turn, is connected to a piston rod  50  of the drive  38 , which is exemplarily implemented in terms of a (pneumatic) cylinder  52 . The housing  54  of the drive  38  encloses the cylinder  52 . The piston rod  50  moves in the horizontal direction Z within the cylinder  52  and thus causes the movement  40  of the carriage  36  via the connecting element  48 . The connecting element  48  couples in a non-positive manner to the carriage  36  via the spring device  42 . If an extension movement of the carriage  36  (movement to the left in  FIG. 1A ) is obstructed by an obstacle such as one of a clip driver  14  and a hanger  12 , or a hook  18 , the spring device  42  can be compressed. Then, the shaft  45  reaches through the carriage  36 , as will be explained in further detail with reference to  FIG. 2B . In this state the carriage  36  temporarily rests and thus has the option to evade the obstacle. In this manner it is achieved that destroying collisions are avoided. 
         [0049]    It is clear that other spring devices  42  can be used instead of the spiral spring  44  such as flat springs, gas-pressurized springs, or the like. 
         [0050]    Further, in  FIG. 1A , for example, two (pneumatic) terminals  56 - 1  and  56 - 2  are illustrated for supplying pressurized air to the drive  38  or the cylinder  52 . 
         [0051]      FIG. 1B  shows a side view of the stop unit  30  of  FIG. 1A . Three hangers  12 - 1 ,  12 - 2 , and  12 - 3  are exemplarily shown, which are transported downstream in a conveying direction  60  being oriented, for example, in parallel relative to the longitudinal direction X. The hanger  12 - 1 , which is located the farthest downstream, has passed the stop unit  30  without being released. The center hanger  12 - 2  is located exactly in the region of the stop unit  30  and is still in engagement with the clip driver  14 - 2 . The hanger  12 - 3 , which is located the farthest downstream, is located in front of the stop unit  30  in terms of material flow. 
         [0052]    Supporting arms  62  of the clip drivers  14  can be recognized in  FIG. 1B , the supporting arms  62  being connected to a conveying chain (which is not illustrated in more detail). Respectively one clip  64  is pivotally supported beneath the supporting arms  62 , the clip  64  being pivotable around a pivotal axis  66 . The pivotal axis  66  is arranged in a region of a downstream located end of the supporting arm  62 , and in the present case it is orientated parallel relative to the transverse direction Z. Pivotal movement  68 , by which the clips  64  can be opened for disengaging the hangers  12  from the clip drivers  14 , is indicated by means of an arrow in  FIG. 1B . The coupling of the supporting arms  62  to the conveying chain, which is not depicted here, can be achieved via coupling elements  70 . 
         [0053]    The clip drivers  14  can be guided in a (vertical) slot  72  within the supporting rail  16 , as can be recognized well in the perspective view of  FIG. 1C . 
         [0054]    With reference to  FIGS. 2A-2C  different states of the stop unit  30  of the invention will be described below.  FIG. 2A  shows different views of a classic release position. The views of  FIGS. 2B  show a release position interpreted narrowly. The views of  FIG. 2C  show a stop position of the carriage  36 , or the stop unit  30 . Each of the  FIGS. 2A-2C  shows a front view (upper part) similar to  FIG. 1A , a top view (center part) as well as an enlarged sectional view (lower part) of the upper front view. The enlargement is respectively indicated in the upper front view by means of a circle being designated by A, B, and C. 
         [0055]      FIG. 2A  shows the classic (normal) release position in which the carriage  36  is completely retracted in the positive direction Z with its stopper  46  by extending the piston rod  50  ( FIG. 1A ) correspondingly. Thus, no collision can happen between the carriage  36  and the hooks  18  of the hangers  12 . All of the hangers  12 - 1  to  12 - 3  shown in  FIG. 2A  can pass the stop unit  30  without collision. 
         [0056]      FIG. 2B  shows the stop unit  30  at a (slightly) later time, when a superordinated (not shown) control (e.g., material flow computer) outputs a signal to the stop unit  30 , which signal causes the stop unit  30  to extract the carriage  36  by retracting the piston  50  in the negative direction Z. If this command is executed at a time when the third hanger  12 - 3  (with the associated clip driver  14 - 3  thereof) just passes the carriage  36 , it can happen that the stopper  46  cannot be extended completely across the entire width B ( FIG. 2C  below) of the supporting rail  16 , but abuts against the clip driver  14 - 3 , which is not shown in  FIG. 2B , or directly against the hook  18 - 3  of the hanger  12 - 3 . The carriage  36  can be moved back against the force of the spiral spring  44  (cf. arrow  90 ), namely along the positive direction Z, even if the driver  38  actually requires movement via the piston rod  50  into the opposite direction. The front view (upper part) of  FIG. 2B  clearly shows how the shaft  45  penetrates through an opening  89  in the spring contact section  88  ( FIG. 1A ) which is implemented by the shorter vertical leg of the carriage  36 . With reference to the  FIGS. 4A  and  4 B it will be described below in more detail how it is possible that the stopper  46  of the carriage  36  performs the retraction movement  90  although the carriage  36  is extracted in an abutting manner against one of the clip drivers  14 . 
         [0057]      FIG. 2C  shows the stop position of the stop unit  30 . The stopper  46  of the carriage  36  is extended so far, in the stop position, along the negative direction Z (cf. arrow  92 , lower part) that the carriage  36  completely projects over the supporting rail  16  with the abutting section  84  thereof. The abutting section  84  is slightly distanced in a vertical direction (direction Y) relative to a top side of the supporting rail  16 , as will be explained in more detail with reference to  FIGS. 3D and 3E . The  FIG. 2C  shows the stop unit  30  at a later time than in  FIG. 2B . The (hitten) hanger  12 - 3  has passed the stop unit  30  so that there is no obstacle for a complete extension movement  92  of the carriage  36  since the third hanger  12 - 3  and the fourth hanger  12 - 4  were sufficiently distanced relative to each other in the conveying direction  60 . Therefore, the subsequent hangers  12 - 4  to  12 - 6  are accumulated at the abutting section  84  of the carriage  36 . The abutting section  84  effects, by means of the upstream located edge thereof, that the clips  64  are rotated upwardly (cf. arrow  68 ) about the pivotal axis  66  ( FIG. 1B ) for releasing the hangers  12  while the clip drivers  14  are continuously moved in the downstream direction. 
         [0058]    It can be recognized in the enlarged illustration of  FIG. 2C  that the abutting section  84  projects the supporting rail  16  over its entire width B. Thus, only perpendicular forces act on the carriage  36  which cannot initiate a retraction movement  90 . A guiding section  86  of the carriage  36  follows the abutting section  84  in the transverse direction Z. The abutting section  84  and the guiding section  86  define the long leg, or stopper  46  (cf.  FIG. 1A ), of the L-shaped carriage  36 . The guiding section  86  can comprise a spring at the top side thereof, the spring projecting upwardly and communicates, in a positive engagement, with a notch of the carriage-guiding rail  36  which is correspondingly open downwardly and not shown in further detail in  FIG. 2C . 
         [0059]    The  FIGS. 3A-3E  show different views of the stop unit  30  in the stop position at different magnifications.  FIG. 3A  shows a side view.  FIG. 3B  shows a top view.  FIG. 3C  shows an enlargement of a region surrounded by a circle in  FIG. 3A .  FIG. 3D  shows a side view, similar to  FIG. 3C , wherein only isolated parts are illustrated.  FIG. 3E  shows a side view of  FIG. 3D  which is schematized stronger. 
         [0060]    In  FIG. 3A  a supporting-rail elevation  94  is shown in addition to the elements of the stop unit  30 , which have been explained up to now. The supporting-rail elevation, or the “elevation”,  94  is adapted to the shape of the supporting rail  16 . The supporting-rail elevation  94  can replace part of the supporting rail  16 , wherein the transitions between the supporting rail  16  and the supporting-rail elevation  94  should be continuous so that the supporting-rail elevation  94  does not represent an obstacle for the transportation of the hangers  12 , if the stop unit  30  is in the release position. Alternatively, the supporting-rail elevation  94  can be clipped onto the supporting rail  16  from the outside. The supporting-rail elevation  94  is characterized by a rise  95 , which will be explained in more detail with reference to  FIG. 3D . The rise  95  projects from the top side of the supporting rail  16  and effects, together with the stopper  46  of the carriage  36  if the carriage  36  is in the stop position, a blockade of the hangers  12  in an intermediate space  96  formed between the extended stopper  46  and the top side of the supporting rail  16 , as will be explained in more detail below. 
         [0061]    In  FIG. 3A  a situation is shown in which the three hangers  12 - 1  to  12 - 3  have already been separated from their associated clip drivers  14 , wherein merely the clip driver  14 - 3  is depicted in terms of its clip  64 - 3 . The clip driver  14 - 3  has just been released from the hanger  12 - 3  so that the hanger  12 - 3  is disengaged from the clip driver  14 - 3 . 
         [0062]      FIG. 3B  shows a top view of the side view of  FIG. 3A . 
         [0063]      FIG. 3C  shows an enlarged illustration of a part of  FIG. 3A . For the sake of a facilitated illustration only the clip  64  is shown. The clip  64  sits with its bottom side on a top side of the stopper  46  of the carriage  36  and is pulled over the top side of the stopper  46  along the conveying direction  60 . The intermediate space  96  is provided between the stopper  46  and the supporting rail  16 . The bottom side of the stopper  46  is located in a plane E 1  extending parallel to a second plane E 2 , which is defined by the top side (sliding area  110 ) of the supporting rail  16 . The distance of the first plane E 1  relative to the second plane E 2  corresponds to a height H 1  of the intermediate space  96 . 
         [0064]    A hook nose  98 , which defines a receiving region, or slot,  100  in the clip  64 , lies, in the present case, above the first plane E 1  and above the second plane E 1  and is positioned at an upstream end of the clip  64 . This merely effects that the hooks  18  are disengaged from the clip  64 , i.e. released. 
         [0065]    Further, it can be recognized in  FIG. 3C  that beside the third hanger  12 - 3 , or the hook  18 - 3 , the first hanger  12 - 1  and the second hanger  12 - 2  are already accumulated in the intermediate space  96 . The rise  95  prevents the hangers  12 - 1  and  12 - 2  from leaving the intermediate space  96  in the conveying direction  60 , since the intermediate space  96  tappers in the downstream direction. 
         [0066]    The supporting-rail elevation  94  and its rise  95  are illustrated in more detail in  FIG. 3D . In the side view of  FIG. 3D  the supporting-rail elevation  94  comprises an, relative to the supporting rail  16 , increasing flank  104 , a plateau which extends preferably in parallel to the supporting rail  16 , as well as a decreasing flank  108 . The supporting-rail elevation  94  has a length X 0 -X 7  in the longitudinal direction X. In the supporting-rail elevation  94  has, in a first section which extends from X 0 -X 2 , an identical height like the supporting rail  16 . This means that a top side of the supporting-rail elevation  94  in the region X 0 -X 2  is located in same plane like the sliding area  110  of the supporting rail  16 . The increasing flank  104  extends from X 2 -X 3 , wherein the height steadily increases up to almost H 1 . The plateau  106  extends from X 3 -X 5  almost on the height H 1 . The plateau  106  is located slightly deeper than the bottom side of the stopper  46  of the carriage  36  for avoiding collisions. The decreasing flank  108  extends from X 5 -X 6 , wherein the height difference, relative to the sliding area  110 , is again reduced to zero. An end section, which has the same level like the supporting rail  16  and which is not designated in more detail in  FIG. 3D , extends from X 6 -X 7 . 
         [0067]    The stopper  46  comprises, in a height direction Y a thickness D. The stopper  46  extends from X 1 -X 4  in the longitudinal direction X. The relative position of the rise  95  relative to the stopper  46  is to be selected such that none of the hangers  12 —in dependence on the (wire) thickness of the hook  18 —can pass the intermediate space  96  inadvertently. The stopper  46  can be supported such that it slightly gives way in the positive direction Y. This will be explained hereinafter in more detail. The stopper  46  preferably overlaps at least part of the plateau  106 . The height of the plateau  106  is selected such that the stopper  46 , in the stop position, does not collide with the rise  95  during extension. 
         [0068]      FIG. 3E  shows the illustration of  FIG. 3D  in a sectional view in abstracted terms, wherein the supporting-rail elevation  94  is not shown. The illustrated sectional plane lies in the plane XY centered in the supporting rail  16  with regard to the extension thereof in the direction Z. In this case, the hook  18  comprises a circular wire. It is clear that other cross sectional geometries can be selected. A center M is at a height H 2 , which is located beneath the bottom side of the stopper  46 , the bottom side having a height H 1 . The height H 2  of the center M of the hook  18  is dependent on the wire diameter as well as on a diameter of the hanger head, which is located in the plane YZ (cf.  FIG. 1A ). In  FIG. 1A  the head of the hanger  18  is situated at two points on the supporting rail  16  so that the vertex of the head is located above the sliding area  110 .  FIG. 3E  shows a sectional view along the longitudinal direction X crossing this vertex. 
         [0069]    This specific geometry ensures that the hook  18  can dive beneath the stopper  46 , if the clip  46  has not released the hook  18 . This is particularly the case if the stopper  46  hits one of the clip drivers  14  at its downstream end when the stopper  46  is extended from the release position to the stop position, wherein the clip driver  14  still holds the hanger  12 . The slot  100  (cf.  FIG. 3C ) is configured such that an engaged hanger  12  can move in the vertical direction Y. 
         [0070]    The situation ( FIG. 2B ) just described generally involves the danger of damaging the overhead conveyor  10 . This damage is avoided by returning the stopper  46  against the force of the spring device  42  (cf. arrow  90  in  FIG. 2B , lower part) by means of the still engaged hanger  12 . This operating principle will be described below with reference to  FIGS. 4A and 4B , which are to be taken in common with  FIGS. 3D and 3E . 
         [0071]    The  FIGS. 4A and 4B  show top views at different times of the system shown in  FIGS. 3D and 3E . 
         [0072]      FIG. 4A  shows a state like  FIG. 2B , in which state the stopper  46  is moved from its release position to the stop position, but is hindered by the clip  64  to completely extend to the stop position. In  FIG. 4A  the front face of the stopper  46  abuts against a side area of the clip  64  engaging the hook  18 . The stopper  46  cannot be extended further, even if the driver  48  still remains activated. The spring device  42  absorbs the force exerted by the drive  38  by compressing the spring device  42  (cf.  FIG. 2B , upper part). The conveying chain (which is not illustrated here) is then moved further downstream along the conveying direction  60  until the situation shown in  FIG. 4B  is achieved, wherein the hook  18  is pulled beneath the stopper  46 . 
         [0073]    The stopper  46  comprises a first oblique front face  114  at the free end  112  thereof, and an (optional) second front face  116  which can be orientated in parallel relative to the side area of the clip  64 . The first oblique front face  114  breaks up the rectangular geometry of the stopper  46  in the region of the free end  112 . In this sense, the free end  112  lacks one “corner”. This missing corner is located, in the longitudinal direction X, in a region of the supporting-rail elevation  94  where the increasing flank  104  is arranged. The first oblique front face  114  serves as a force-introduction area, which is required for returning the stopper  46  against the force of the drive  38 . 
         [0074]    As soon as the hook  18  is in contact with the stopper  46 , because the conveying movement, of course, is continued, the hook  18  will be pulled beneath the stopper  46  due to the special arrangement (cf.  FIG. 3E ) as well as due to its geometry and the geometry of the slot  100  in the clip  64 . As soon as the hook  18  has reached the increasing flank  104  (cf.  FIG. 3D ), the intermediate space  96  tapers. The conveying movement, however, still continues. There is a space at one (free) side opposite to the stopper  46  for moving the hook  18  in a vertical upward direction. The continued conveying movement then results in a rotational movement  120  of the hook  18 , since the hook  18  is jammed by the increasing flank  104  at one of the sides which is facing the stopper  46 . 
         [0075]    As soon as the hook  18  has rotated to the position shown in  FIG. 4B , the hook  18  exerts a force F onto the first oblique front face  114  which causes the retraction movement  90  ( FIG. 2B , low part) of the stopper  46 . Then, the path of the engaged hook  18  is free for passing the stop unit  30  in the conveying direction  60 . Damage is prevented. 
         [0076]    The first front face  114  forms an angle α together with the longitudinal direction X of the supporting rail  16 . The angle α is, for example, 45° and typically lies in a range of 45°±25°. 
         [0077]      FIG. 5  shows a modified embodiment of the abutting section  84  of the carriage  36 . The front face of the stopper  46  is oriented obliquely over its entire length relative to the longitudinal direction X. The free end  112  comprises a tip  118 ′, which is tapered to a point, whereas the tip  118  of the stopper  46  of  FIGS. 4A and 4B  defines a rectangular angle. 
         [0078]    In the above description of the invention identical parts and features have been designated by the same reference numerals, wherein the disclosures contained in the entire description can be transferred to parts and features having the same reference numerals. Indications of positions such as “above”, “below”, “lateral”, “vertical”, “horizontal”, etc. are related to the immediately described drawings and are to be transferred to a new position correspondingly, if position changes. 
         [0079]    Further, it is to be noted that indications of directions and orientations were considered which, in principle, refer to the designations typically used in (intra-)logistics. Hence, the longitudinal direction (conveying direction) is designated by “X”, the depth (width) is designated by “Z”, and the (vertical) height is designated by “Y”. A corresponding (Cartesian) coordinate system X, Y, Z can be derived respectively from the figures. 
         [0080]    Therefore, what we claim is: