CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application claims Priority from German Application No. DE 10 2007 034 197.2 filed on Jul. 23, 2007. 
       FIELD OF THE DISCLOSURE 
       [0002]    The present disclosure relates to an apparatus for loading and unloading a tray of a freeze drying plant as set forth in the preamble of the claims  1  and  2 , as well as to a method for a respective one thereof, according to the preamble of the claims  16  and  17 . 
         [0003]    The material to be dried in a freeze drying plant is filled into small bottles which are referred to as vials and transported with the help of said vials. Lids are provided on these vials and are closed upon completion of the freeze drying process. 
         [0004]    The vials, which are filled with the material to be freeze dried and whose lid is still open, are brought onto a transfer table from where they are conveyed to a tray in the interior of the freeze drying plant by means of a pusher apparatus. In the freeze drying plant there are provided a plurality of trays, which, for loading the freeze drying plant, are taken from a stack, raised to the height of the transfer table and loaded with the vials. Once the tray is filled, said tray is moved upward together with the already previously filled trays and the next tray is taken from the stack and brought to the level of the transfer table, and so on. Upon completion of the freeze drying process, the trays are brought together in such a manner that the tray located above the vials comes to rest on the lids of the vials which it pushes into the vials so that the vials are henceforth closed. Then, the trays are again pulled apart for the tray located on the height of the transfer plate to be unloaded. As soon as this tray has been unloaded, it is brought to the bottom of the freeze drying plant where it is stacked whilst the next tray is moved to the level of the transfer table in order to be unloaded, and so on. 
       BACKGROUND OF RELATED ART 
       [0005]    A device for loading and unloading a tray of a freeze drying plant is known from EP 1 619 459 A1, the pusher apparatus thereof including a bar that is adapted for upward and downward pivotal movement and that is retained on a carriage guided on the right and on the left side of the transfer table and on the tray. The carriages are guided on special rails which are attached to the right and left edge of the transfer plate and of the tray. The rails are configured to be a web protruding upwards at right angles and concurrently forming a lateral limitation for the vials located on the transfer table or on the tray. 
         [0006]    To load the tray with a number of vials, said vials are at first placed onto the transfer table. As soon as there are enough vials on the table, the bar retained on the carriages is brought to the foremost vials, a flexible metal tape being attached to a respective one of the right and left carriages and being actuated through a drive. Then, the bar is moved further in the direction of the tray, thus pushing the vials in front of it. The rails, which act as a side limitation, hereby ensure that no vials will fall down from the transfer table or from the tray. As soon as the foremost vials have been placed onto the tray, the metal tapes pull the carriages, and as a result thereof the bar, back into the initial position before the bar is pivoted away upward through a pivoting mechanism mounted to the carriage for the next vials to be passed underneath the bar and be placed onto the transfer plate. At the same time, the now filled tray is moved upward in the freeze drying plant and the next, empty tray is provided. If enough vials are on the transfer table, this process is repeated and the pusher device pushes the next group of vials onto the next tray. 
         [0007]    For unloading, the bar is again travelled upward through the pivoting mechanism and, through the flexible tapes, is brought together with the carriage as far as the rear edge of the tray where the bar is lowered again. Then, the tapes are pulled tight again, thus pulling the carriage and the bar together with the vials from the tray onto the transfer table from where the vials are then evacuated. 
         [0008]    Upon pushing the vials from the transfer plate onto the tray, it may happen that the vials, which had originally been placed correctly in discrete rows, get disarranged, some vials also being brought as far as the rail confining them laterally. If the number of vials continues to be pushed onto the tray, the outer vials are caused to touch the rail, the vials getting even more disarranged due to the occurring friction. Some vials may also tumble. 
         [0009]    Upon completion of the freeze drying process, the pusher apparatus is moved as far as the rear border of the tray by means of the carriages guided on the rails. Often, the carriage needs to push vials located close to the rail slightly aside in order to arrive at the rear end of the tray. Hereby, the vials are even further disarranged and discrete vials can tumble. 
         [0010]    During unloading, the vials are now at first pushed together in analogous fashion in the opposite direction and are moved from the tray onto the transfer table. Again, a friction occurs between the outer vials and the rail confining the sides so that the vials get even more disarranged and that a vial may tumble. 
         [0011]    Moreover, it happens that some vials get stuck on the underside of the tray located above after the freeze drying process. If now the pusher device is introduced with the bar into the freeze drying plant, the bar hits the vials sticking on the underside of the next tray; as they fall down, these vials can tip over. 
         [0012]    Food or drugs are often processed in freeze drying plants. As a result, the hygiene requirements are very demanding. As a result, tipped over vials are not allowed to be processed further and constitute scrap material. 
       SUMMARY  
       [0013]    In view thereof, it is the object of the present disclosure to provide an apparatus and a method of the type mentioned herein above for the vials to be transferred with little friction and securely to the tray and back. 
         [0014]    As a first technical solution to this object, an apparatus for loading and unloading a tray of a freeze drying plant having the features of claim  1  and a method of loading and unloading a freeze drying plant having the features of claim  16  are proposed. Advantageous developments of this apparatus will become apparent from the respective dependent claims. 
         [0015]    An apparatus for loading and unloading a tray of a freeze drying plant configured in accordance with this technical teaching and a method for loading and unloading a tray of a freeze drying plant configured in accordance with this technical teaching have the advantage that a side boundary is provided by positioning the transport carriage on the right and left border of the transfer table or of the tray, which prevents the vials from falling down. It is particularly advantageous to place the transport carriages for the vials located on the border to directly abut the transport carriage during loading and unloading. 
         [0016]    Taking into consideration that the vials are moved into the freeze drying plant or out of it together with the transport carriages, the vials can be well guided by the transport carriages serving as side boundaries. Taking further into consideration that the transport carriages and the vials are moved in the same direction, it appears that the relative velocity between the transport carriages and the vials is minimized by virtue of this arrangement. Advantageously, the vials move at the same speed as the transport carriages so that the relative velocity is reduced to zero. This offers the advantage that between the vials located on the border and the transport carriages there is no friction so that they are prevented from inadvertently tipping over, which generates less scrap and thus improves the efficiency of the freeze drying process. 
         [0017]    Moreover, it is thus achieved that the vials remain in the order in which they were placed so that each vial stays in an exactly defined position before and after unloading. Through this concrete positioning of the vials, it is possible to better control the freeze drying process since only the quality of the products contained in the vials will allow to draw conclusions on the freeze drying process. If it is found out for example that always the vials in a certain position have insufficient freeze drying quality, the freeze drying method can be improved in this point with the aim of reducing the generated scrap material. 
         [0018]    Still another advantage is that, for quality control, only those vials must be examined, which were on critical positions on the tray in order to see the overall quality of the freeze drying process. Accordingly, the number of random samples can be reduced, whilst the examination result is improved. 
         [0019]    As a second technical teaching to this solution, an apparatus for loading and unloading a tray of a freeze drying plant having the features of claim  2  and a method of loading and unloading a freeze drying plant having the features of claim  17  are proposed. Advantageous developments of this apparatus will become apparent from the respective dependent claims. 
         [0020]    An apparatus for loading and unloading a tray of a freeze drying plant configured in accordance with this technical teaching and a method for loading and unloading a tray of a freeze drying plant configured in accordance with this technical teaching have the advantage that, by displacing the transport carriages transverse to the travel direction, a distance can be created between the transport carriage and the vials. This offers the advantage that the transport carriages can be brought close to the vials located on the edge of the transfer table or on the edge of the tray during direct loading or unloading for example, meaning during a sliding travel, for a good guidance of the vials so that no vials will tip over and that the vials remain in the existing order and sequence whilst the transport carriages are moved at a distance from the vials, for example during a movement in which the vials are not being displaced, meaning during an empty run, in order to avoid contact with the vials so that no vials will tip over during the empty run and that the vials remain in the existing order and sequence. 
         [0021]    In a preferred embodiment, a guide element is disposed here on the right and the left edge of the transfer table and/or of the tray, for the transport carriage to rest thereon. This guide element is placed so that the transport carriage resting thereon serves for laterally delimiting the transfer table and/or the tray. It has been found advantageous to have the guide element extend as far as the rear edge of the tray for the transport carriage, in particular the pusher chain, to be correctly guided over its entire length and to prevent it from inadvertently sliding partially away or falling down. 
         [0022]    In a particularly preferred embodiment, a guiding groove is formed on the guide element, a downward extending guiding pin mounted to the underside of the transport carriage extending into said groove. This offers the advantage that the guiding pin interlockingly prevents the transport carriage from sliding out of place laterally. 
         [0023]    In a preferred developed implementation, the guide element is retained on the transfer table and/or on the tray for lateral displacement by about 1 mm to 10 mm, preferably by 4 mm. This offers the advantage that these guide elements can be moved readily at low cost, such as pneumatically, electrically or hydraulically. 
         [0024]    In an alternative preferred embodiment, an inner groove and an outer groove are formed in the guide element, a downward extending guide pin being formed on the underside of the transport carriage for engagement into the inner or into the outer groove, depending on the situation. It has proved advantageous to arrange the inner groove and the outer groove parallel to each other. 
         [0025]    A thus configured guide element has the advantage that the transport carriage resting on the guide element is shape-matingly secured from sliding laterally out of place by the guide pin guided in the inner or in the outer groove. The transport carriage is thereby free to move forward and backward in the direction of movement since the inner groove and the outer groove, which are also oriented in the direction of movement, do not constitute any obstacle in this direction but do constitute an obstacle in a direction transverse to the direction of movement so that the transport carriage is secured from sliding laterally out of place. 
         [0026]    In a preferred developed implementation, at least two connecting grooves are provided between the inner groove and the outer groove. As a result, it is possible for the transport carriage to be transferred with its guide pin from the inner groove into the outer groove for example insofar as the guide pin is guided through the respective one of the connecting grooves and vice versa. This offers the advantage that the transport carriage can be guided both in the inner and in the outer groove, depending on the case of application. As a result, the transport carriage is moved at a distance from the vials during an empty run. 
         [0027]    In another preferred developed implementation, at least two, preferably eight, guide pins are provided on the underside of the transport carriage in order to reliably avoid unwanted lateral displacement of the transport carriage over its entire length. The connecting grooves are thereby arranged such that the guide pins are located in the region of the connecting grooves when the transport carriage has been extended. As a result, the transport carriage can be readily displaced, through the respective connecting grooves, for example from the inner groove, into the outer groove and vice versa. 
         [0028]    The transport carriage can be configured to be either a rod or a pusher chain. 
         [0029]    In another preferred embodiment, a centering apparatus is disposed in the freeze drying plant, behind the tray to be loaded, for taking hold of the head of a transport carriage. This offers the advantage that the transport carriage, or at least part thereof, can be reliably transferred into the respective other groove. If the transport carriage is configured to be a pusher chain, the centering apparatus only displaces the head of the pusher chain and some of the chain links adjoining said head. On the opposite side, the pusher chain, together with some adjoining chain links, are displaced by the drive of the pusher chain, a more or less large central region remaining to a more or less large extent inside the output groove. If the pusher chain is again caused to move out of the freeze drying plant, the pusher chain pulls itself straight by itself. 
         [0030]    Further advantages of the apparatus of the disclosure for loading and unloading a tray of a freeze drying plant and of the methods of the disclosure for loading and unloading a tray of a freeze drying plant will become apparent in the appended drawings and in the following description of embodiments thereof. Likewise, the disclosure lies in each and every novel feature or combination of features mentioned above or described herein after. The embodiments discussed herein are merely exemplary in nature and are not intended to limit the scope of the disclosure in any manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0031]    In said drawings: 
           [0032]      FIG. 1   a  shows in a schematic illustration a sectional side view of a first embodiment of an apparatus of the disclosure and of a freeze drying plant at a first time period, taken along line Ia-Ia in  FIG. 1   b;    
           [0033]      FIG. 1   b  is a sectional top view of the apparatus and the freeze dryer plant shown in  FIG. 1   a , taken along line Ib-Ib in  FIG. 1   a;    
           [0034]      FIG. 1   c  is a sectional front view of the apparatus. 
           [0035]    and the freeze drying plant as shown in  FIG. 1   a , taken along line Ic-Ic in  FIG. 1   a;    
           [0036]      FIG. 1   d  is an enlarged detail of the apparatus of the disclosure, taken along line Id in  FIG. 1   c;    
           [0037]      FIG. 1   e  is an enlarged detail of the apparatus of the disclosure, taken along line Ie in  FIG. 1   b;    
           [0038]      FIG. 1   f  is a sectional side view of the enlarged detail as shown in  FIG. 1   e,  taken along line If-If in  FIG. 1   e;    
           [0039]      FIG. 2   a  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a second time period, taken along line IIa-IIa in  FIG. 2   b;    
           [0040]      FIG. 2   b  is a sectional top view of the apparatus and of the freeze drying plant as shown in  FIG. 2   a , taken along line IIb-IIb in  FIG. 2   a;    
           [0041]      FIG. 2   c  is an enlarged detail of the apparatus of the disclosure, taken along line IIc in  FIG. 2   b;    
           [0042]      FIG. 3   a  is a sectional top view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a third time period; 
           [0043]      FIG. 3   b  is an enlarged detail of the apparatus of the disclosure taken along line IIIb in  FIG. 3   a;    
           [0044]      FIG. 4  is a sectional top view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a fourth time period; 
           [0045]      FIG. 5  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a fifth time period; 
           [0046]      FIG. 6  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a sixth time period; 
           [0047]      FIG. 7  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a seventh time period; 
           [0048]      FIG. 8   a  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at an eighth time period; 
           [0049]      FIG. 8   b  is an enlarged detail view of the apparatus of the disclosure taken along line VIIIb in  FIG. 8   a;    
           [0050]      FIG. 9  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a ninth time period; 
           [0051]      FIG. 10  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a tenth time period; 
           [0052]      FIG. 11  is a sectional side view of the apparatus and of the freeze drying plant as shown in  FIG. 1   a , at a eleventh time period; 
           [0053]      FIG. 12   a  is a schematic sectional side view of a second embodiment of an apparatus of the disclosure and of a freeze drying plant at a first time period; 
           [0054]      FIG. 12   b  shows the apparatus as shown in  FIG. 12   a  at a second time period; 
           [0055]      FIG. 12   c  shows the apparatus as shown in  FIG. 12   a  at a second time period; 
           [0056]      FIG. 13   a  is a schematic sectional top view of a third embodiment of an apparatus of the disclosure and of a freeze drying plant at a first time period, taken along line XIIIa-XIIIa in  FIG. 13   c;    
           [0057]      FIG. 13   b  shows an enlarged detail of the apparatus of the disclosure as shown in  FIG. 13   a , taken along line XIIIb in  FIG. 13   a;    
           [0058]      FIG. 13   c  is a sectional front view of the apparatus and the freeze drying plant shown in  FIG. 13   a , taken along line XIIIb-XIIIb in  FIG. 13   a;    
           [0059]      FIG. 13   d  is a sectional view of an enlarged detail of the disclosure as shown in  FIG. 13   c , taken along line XIIId-XIIId in  FIG. 13   c , at a first time period; 
           [0060]      FIG. 13   e  shows the enlarged detail of  FIG. 13   d , at a second time period; 
           [0061]      FIG. 14   a  is a schematic sectional side view of a fourth embodiment of an apparatus of the disclosure and of a freeze drying plant at a first time period, taken along XIVa-XIVa in  FIG. 14   b;    
           [0062]      FIG. 14   b  is a sectional top view of the apparatus and of the freeze drying plant as shown in  FIG. 14   a , taken along line Linie XIVb-XIVb in  FIG. 14   a;    
           [0063]      FIG. 14   c  is a sectional front view of the apparatus and of the freeze drying plant shown in  FIG. 14   a , taken along line XIVc-XIVc in  FIG. 14   a;    
           [0064]      FIG. 14   d  shows an enlarged detail of the apparatus of the disclosure as shown in  FIG. 14   a , taken along line XIVd in  FIG. 14   c;    
           [0065]      FIG. 14   e  shows an enlarged detail of the apparatus of the disclosure as shown in  FIG. 14   a , taken along line XIVe in  FIG. 14   c;    
           [0066]      FIG. 14   f  is a sectional side view of an enlarged detail as shown in  FIG. 14   e , taken along line XIVf-XIVf in  FIG. 14   e.    
       
    
    
     DETAILED DESCRIPTION 
       [0067]    The  FIGS. 1   a  through  1   f  show, in a schematic illustration, an apparatus of the disclosure for loading and unloading a tray of a freeze drying plant and such a freeze drying plant  10 . This freeze drying plant  10  includes a large chamber  12  that is provided on one side with an opening  14  for loading and unloading. This opening  14  can be closed with a door that has not been illustrated herein. Inside the chamber  12 , there is provided a number of trays  16  that are adapted for vertical travel through a mechanism that has not been illustrated herein. 
         [0068]    The apparatus for loading and unloading a tray and the freeze drying plant associated therewith illustrated in the drawing are illustrated merely schematically. Many details have been omitted in order to allow for increased clarity in illustrating the basic principle of the apparatus and of the freeze drying plant. 
         [0069]    The product to be dried is usually filled into small bottles referred to as vials  18 , said vials  18  being provided with a lid which is open before the freeze drying process, said lid being closed after the freeze drying process in order not to soil the freeze dried product. Such an apparatus for loading and unloading a tray of a freeze drying plant and the freeze drying plant itself are usually placed in clean rooms for the drugs contained in the vials not to be contaminated. This however also means that the entire loading and unloading process must be completely automated. 
         [0070]    The apparatus for loading and unloading a tray  16  of a freeze drying plant  10  with a number of vials  18  includes a transfer table  20  on which the vials  18 , which usually arrive one by one or in rows, are collected until a sufficient number of vials  18  is available on the transfer table  20 . The transfer table  20  is thereby configured to be a planar, level surface and is limited on the right and on the left side by a respective guide element  22 . In the embodiment shown, the guide element  22  is directly connected to the transfer table  20 , the upper side of the guide element  22  being flush with the top side of the transfer table  20 . In the guide element  22 , an outer groove  24  is provided on the outer edge, said groove extending over the entire length of the guide element  22 . Directly next to the outer groove  24  there is provided an inner groove  26 , which is offset slightly inward parallel to the outer groove  24  and which also extends over the entire length of the guide element  22 . 
         [0071]    As can be inferred in particular from  FIG. 1   b , each of the trays  16  comprises on its right and left edge a corresponding guide element  22 ′, each of them also respectively having an outer groove  24  and an inner groove  26 . For loading the tray  16 , said tray is caused to travel into the region of the opening  14  by means of the hoist mechanics that has not been illustrated herein so that the guide element  22  and the guide element  22 ′ abut flush with each other. As a result, the outer groove  24  and the inner groove  26  of the guide element  22  directly merges into the outer groove  24  and the inner groove  26  of the guide element  22 ′, as can be seen best from  FIG. 1   d.    
         [0072]    Between the outer groove  24  and the inner groove  26  there are provided at certain intervals connecting grooves  28  which connect the outer groove  24  and the inner groove  26 . The connecting grooves  28  are many times longer than the diameter of the guiding pin  36 . 
         [0073]    On each of the guide elements  22 , which are arranged flush with the transfer table  20 , there is disposed one transport carriage configured to be a pusher chain  30 . This pusher chain  30  is stored on a cylinder  32  that causes it to move. The direction of rotation of the cylinder  32  determines the direction in which the pusher chain  30  moves. The cylinder  32  guides the pusher chain  30  about a deflection pulley  34  to the guide element  22  on the transfer table  20 . The pusher chain  30  itself is composed of a number of individual links that are movable with respect to each other and which has certain stiffness while it pushes so that it can be utilized similar to a rod. At the underside of the pusher chain  30 , there are disposed at regular intervals guiding pins  36 , as can be seen best from  FIG. 1   f . At the time period shown in the  FIGS. 1   a  through  1   f , the guiding pins  32  of the pusher chain  30  engage the inner groove  26  of the guide element  22 , thus reliably guiding the pusher chain  30  on the edge of the transfer table  20  or of the tray  16 . It is understood that the guiding pins  36  are adapted to the size of the inner groove  26  or of the outer groove  24 . As explained in closer detail herein after, the pusher chain  30  with its guiding pins  36  can also be guided in the outer groove  24 . 
         [0074]    In addition to the right and left pusher chain  30 , the pusher device also has a loading element configured to be a loading pusher  38  that can be stowed in a shelf  40  located above the transfer table  20  when not needed. In this case, the loading pusher  38  is placed so far at the top on the shelf  40  for the vials  18  to be capable of passing underneath the loading pusher  38 . The shelf  40  is provided with a corresponding automated mechanics and can place the loading pusher  38  onto the right and the left pusher chain  30  from where it can be retrieved in due time. On the right and on the left side of the loading pusher  38 , long holes  42  engage into corresponding pins  54  on one of the links of the pusher chain  30  for the loading pusher  38  to be thus reliably retained on the right and left pusher chain  30 .  1   f  now the right and the left pusher chain  30  are moved towards the tray  16 , the loading pusher  38  is entrained, thereby pushing the vials  18  located on the transfer table  20  in front of it until they arrive on the tray  16 . 
         [0075]    As can be seen in particular from the  FIGS. 1   b  and  1   c , the right and the left pusher chain  30  is disposed on the transfer table  20 , meaning on the guide element  22  for the pusher chains  30  forming a lateral limitation of the transfer table  20 . The vials  18  are placed so close on the transfer table  20  that the vials  18  placed on the border can hit the corresponding pusher chain  30 . This applies in an analogous fashion for the tray  16 . 
         [0076]    The apparatus for loading and unloading a tray also has two centering apparatus  44  that are mounted to a wall of the chamber  12  of the freeze drying plant  10  that is opposite the opening  14 . Each of these centering apparatus  44  are positioned so as to be capable of receiving a head  46  of the pusher chain  30  as soon as said chain has passed the rear edge of the tray  16 . The centering apparatus  44  is displaceable horizontally in order to transfer the pusher chain  30  from the inner groove  26  into the outer groove  24  and vice versa. Details thereof will be described in detail herein after with respect to the loading method. 
         [0077]    In order to prevent the head  46  of the pusher chain  30  from falling down when said head  46  projects beyond the rear edge of the tray  16 , a supporting table  47  is provided there. As a result, the head  46  always finds the way into the centering apparatus  44 . 
         [0078]    The apparatus for loading and unloading a tray  16  of a freeze drying plant  10  also possesses a retaining mechanism  48  for receiving an unloading pusher  50 . Just like the centering apparatus  44 , the retaining mechanism  48  is also mounted to the wall of the chamber  12  of the freeze drying plant  10  that is opposite the opening  14 . It is understood that both the centering apparatus  44  and the retaining mechanism  48  are mounted to the chamber  12  together with the unloading pusher  50  so as not to hinder the vertical motion of the trays  16 . The retaining mechanism  48  carries the unloading pusher  50  if it is not needed for unloading the trays  16 . On the other side, the retaining mechanism  48  is capable of settling the unloading pusher  50  onto the pusher chains  30  deployed as far as behind the rear edge of the tray  16  in such a manner that long holes  52  of the unloading pusher  50  located on the right and left edge engage into mating pins  54  provided on the pusher chain  30  for the right and the left pusher chain  30  to be capable of entraining the unloading pusher  50 . 
         [0079]    The method for loading and unloading the tray  16  of the freeze drying plant  20  with a number of vials  18  will be described in detail herein after. 
         [0080]    To load a tray  16  of the freeze drying plant  10 , the uppermost tray  16  of the stack located on the bottom of the chamber  20  is moved upward with a mechanics that has not been illustrated herein so that the tray  16  is flush with the transfer table  20 . It is understood that the door of the freeze drying plant  10  has been opened before. A supplying device  56 , which has been merely outlined herein, supplies the vials  18 , which are collected on the transfer table  20 . These vials  18  are thereby placed in rows, one row of vials  18  extending from a right pusher chain  30  to a left pusher chain  30 . The spacings are thereby dimensioned for the desired number of vials  18  to register between the pusher chains  30 . The pusher chains  30  are thereby deployed so far that their front head lies in front of the first row of vials  18  on the transfer table  20 . As soon as all the vials  18  have been gathered on the transfer table, the shelf  40  lowers the loading pusher  38  from its raised position onto the right and onto the left pusher chain  30 , the long holes  42  of the loading pusher  38  receiving a pin  54  mounted on the top side of the pusher chain  30 . 
         [0081]    Next, the cylinder  32  is put into operation and drives the right and the left pusher chain  30  together with the loading pusher  38  forward for the vials  18  to be pushed from the transfer table  20  to the tray  16 . The vials  18 , the right and the left pusher chain  30  and the loading pusher  38  are forced to move at the same speed so that no friction occurs between the vials  18  disposed on the border and the pusher chains  30 . As a result, no friction occurs between the vials  18  and the pusher chain while the tray  16  is being loaded so that no vial  18  can tip over. Another advantage is that through this orderly displacement of the vials  18  the sequence and order of the vials  18  on the transfer table  20  is maintained. 
         [0082]    In the  FIGS. 1   a  through  1   f , the apparatus of the disclosure and the freeze drying plant  10  is illustrated at a first time period, shortly before the vials  18  are displaced from the transfer table  20  onto the trays. In the  FIGS. 2   a  through  2   c , there is illustrated a second time period at which the vials  18  have completely arrived on the tray  16  and at which the pusher chains  30  are in their completely extended end position. 
         [0083]    As can be seen in  FIG. 2   c  in particular, the head  46  of the pusher chain  30  is taken hold of by the centering apparatus  44  as soon as the pusher chain  30  has reached its end position, the head  46  resting on the supporting table  47 . The centering apparatus  44  thereby also fixes the head  46  of the pusher chain  30  and pushes the head  46 , and as a result thereof at least one part of the pusher chain  30 , from the inner groove  26  onto the outer groove  24 . At the same time, the deflection pulley  34  at the other end of the pusher chain  30  is also offset outward for this part of the pusher chain  30  to be also transferred from the inner groove  26  onto the outer groove  24 . Now, large portions of the pusher chain  30  are in the outer groove  24 , whilst in the center area of the pusher chain  30  parts may still lie on the inner groove  26  or in the connecting webs  28 . As soon however as the pusher chain drive pulls the pusher chain  30  tight, all of the remaining parts of the pusher chain  30  are pulled into the outer groove  24 . 
         [0084]    As can be seen from  FIG. 3   b  in particular, the pusher chain  30  is now guided in the outer groove  24  and is spaced a significant distance from the vials  18 . In the  FIGS. 3 and 3   b , this third time period is shown. 
         [0085]    Then, the two pusher chains  30  are pulled out of the freeze drying plant  10  together with the loading pusher  38 , said pusher chain  30  winding onto the cylinder  32  as is best seen from  FIG. 4 . Arrived at the shelf  40 , the loading pusher  38  is taken hold of by the shelf  40  and raised. 
         [0086]    As soon as the pusher chain  30  is wound as far as possible on the cylinder  32 , the deflection pulleys  34 , which are not shown in closer detail in  FIG. 4 , are moved inward for the pusher chain  30  to be transferred from the outer groove  24  into the inner groove  26 . It is understood that, upon transfer of the pusher chain  30  from the outer groove  24  into the inner groove  26 , the guiding pins  36  disposed underneath the pusher chain  30  are guided via the connecting grooves  28 , as this is best illustrated in the  FIGS. 1   e  and if. Associated therewith, the fully loaded tray  16  is moved further upward inside the chamber  12  together with the trays  16  loaded before and the next tray  16  is taken from the stack and brought to the transfer table  20 , as it is shown in  FIG. 5  at a fifth time period. Now, the loading process can begin again. 
         [0087]    As soon as all the trays  16  are loaded, the transfer table  20  is removed from the freeze drying plant  10  and the door of the freeze drying plant, which has not been illustrated herein, is closed for the actual freeze drying process to take place. 
         [0088]    Upon completion of the freeze drying process, the trays  16  are caused to travel vertically downward simultaneously or consecutively for the tray to abut the vials located underneath, thus pushing the lid located in the vials downward and closing them. Next, the trays  16  are again spaced slightly apart so as to allow for unloading the trays. Now, the door of the freeze drying plant  10  is opened again and the transfer table  20  is moved to the opening  14  in order to unload the first tray  16 . At the sixth time period shown in  FIG. 6 , some trays  16  have already been unloaded and stacked on the bottom of the chamber  12 . Another tray  16  is moved flush with the transfer table  20  and ready for unloading. For this purpose, the two pusher chains  30  are now moved into the freeze drying chamber  12  in the respective outer groove  24  on the guide elements  22  and  22 ′ without the loading pusher  30  until the head  46  of the pusher chain  30  reaches the centering apparatus  44  for the tongs  58  to fix the head  46  of the pusher chain  30 , as this is shown in  FIG. 7  at the seventh time period. 
         [0089]    Next, the deflection pulley  34  and the centering apparatus  44  are caused to move in the opposite direction for the pusher chains  30  to be displaced from the outer groove  24  into the inner groove  26  as shown in the  FIGS. 8   a  and  8   b  at the eighth time period. 
         [0090]    Next, the retaining mechanics  48  places the unloading pusher onto a foremost link of the pusher chain  30  for the pin  54  to engage the long hole  52  of the unloading pusher  50 , thus retaining it. This ninth time period is shown in  FIG. 9 . 
         [0091]    Next, the cylinder  32  pulls the pusher chains  30  together with the unloading pusher  50  out of the chamber  12 , the pusher chains  30  winding again on the cylinder  32 . As soon as all the vials  18  have arrived on the transfer table  20 , as is shown in  FIG. 10  at the tenth time period, the vials  18  are evacuated for further processing through an evacuation device  56  that has not been illustrated herein. Since no relative movement takes place between the vials  18  and the pusher chain  30  when the vials  18  are being removed from the freeze drying plant  10 , the vials  18  keep their positions relative to the other vials  18 . As a result, it is possible to conclude the quality of the freeze drying process via a quality control of the products contained in the vials. Also, through this known position of the discrete vials  18 , it is possible to remove from the plant at a later stage those vials  18  that were located on critical points on the tray  16 . As a result, the quality control of the freeze drying process is facilitated since only the known, critical vials  18  need to be subjected to quality control in order to allow for detecting the quality of the freeze drying process. 
         [0092]    Once all the vials have been evacuated, the pusher chains  30  are again moved together with the unloading pusher  50  as far as the rear wall of the chamber  12  for the retaining mechanism  48  to be capable of receiving again the unloading pusher  50  as this can be seen at the eleventh time period shown in  FIG. 11 . Next, the centering apparatus  44  again take hold of the heads  46  of the pusher chains  30  and transfer pusher chains  30  in the way described before from the inner groove  26  into the outer groove  24  before the pusher chains  30  are again pulled out of the freeze drying plant by the cylinder  32 . Now, the tray  16 , which has been emptied in the meantime, is placed onto the stack on the bottom of the chamber  12  and the next tray  16  is moved to the transfer table  20  to be emptied before the next tray  16  is emptied in the way described. This process is repeated until all of the trays  16  are empty. 
         [0093]    The advantage of mounting the unloading pusher  50  to the rear wall of the chamber  12  is that the unloading pusher needs not be passed over the freshly closed vials  18  in order to remove the vials  18  from the tray  16 . As a result, the vertical spacing between neighbouring trays  16  can be reduced so that, although the chamber keeps the same size, additional trays can be integrated, this in turn increasing the economic efficiency of the freeze drying plant. 
         [0094]    Another advantage is that the vials, which sometimes adhere to the upper tray, can no longer be detached by the incoming unloading pusher and overturn. With the unloading pusher disposed behind the trays, one achieves that the vials adhering to the upper trays are only detached if the entire field of the vials is moved toward the output. In this case, the vial falling down from the top is guided by the neighbouring vials so that this vial cannot fall down. This is also promoted by the fact that the free space between the upper edge of the vials and the underside of the next tray is smaller. In other words, the vial cannot fall so low when it detaches from the upper tray so that the probability for the vial to tilt over is reduced to a minimum. 
         [0095]    The  FIGS. 12   a  through  12   c  schematically show a second embodiment of an apparatus of the disclosure. This second embodiment only differs from the first embodiment shown in the  FIGS. 1   a  through  1   f  by the fact that a pusher  238  is utilized for pushing the vials  218  instead of the loading pusher. This pusher  238  is caused to move by a separate apparatus that has not been illustrated herein, said apparatus being connected to the actual pusher  238  through a connecting rod  239 . This pusher extends over the entire width of the transfer table  220 , meaning from the left pusher chain  230  to the right pusher chain  230 . As can be seen from  FIG. 12   a  in particular, the vials  218  are delivered through the feeding device  256 . From there, the vials  218  are pushed by the pusher  238  onto the transfer table  220 . As soon as enough vials  218  have gathered on the transfer table, the pusher  238  acts onto the foremost vials  218  and pushes all of the vials  218  located on the transfer table  220  onto the tray  216 , as can be seen from the  FIGS. 12   b  and  12   c . The pusher chains  230  are thereby driven forward at the same speed as the pusher  238  for no friction to occur between the pusher chains  230  and the vials  218  abutting thereon so that no vials  218  will tip over and for the vials  218  to arrive on the tray  216  in the given classification. For the rest, this second embodiment is identical with the first embodiment shown in the  FIGS. 1   a  through  1   f  and described herein above. 
         [0096]    In the  FIGS. 13   a  through  13   e , there is schematically illustrated a third embodiment of an apparatus of the disclosure. This third embodiment differs from the first embodiment shown in the  FIGS. 1   a  through  1   f  by the mere fact that the guide element  322  retained on the transfer table  320  and the guide element  322 ′ retained on the tray  316  only comprises one single guiding groove  325  and that no centering apparatus is provided. Instead, the guiding elements  322  and  322 ′ are retained for lateral displacement on the transfer table  320  and on the tray  316 , said guiding elements  322  and  322 ′ being displaceable towards the right and towards the left by 1 mm through 30 mm, preferably by 15 mm, so that the transport carriage, which is configured to be a pusher chain  330 , can be spaced apart from the vials  318  at need. This preferably occurs whenever the pusher chain  330  has to make an empty run in order for it to get spaced from the vials  318  normally abutting the pusher chain  330  so that these vials  318  will not inadvertently tip over or become displaced from their original position. The laterally slidable guiding elements  322  and  322 ′ are thereby operated by a pneumatic control. For the rest, this third embodiment is identical with the first embodiment illustrated in the  FIGS. 1   a  through  1   f  and described herein above. 
         [0097]    In the  FIGS. 14   a  through  14   f , there is schematically shown a fourth embodiment of an apparatus of the disclosure. This fourth embodiment merely differs from the first embodiment shown in the  FIGS. 1   a  through  1   f  by the fact that a rod  430  is utilized instead of the pusher chain. Like the pusher chain, this rod  430  is guided in the inner groove  426  or in the outer groove  424  via guiding pins  436  and has on its upper side pins  454  for receiving the loading pusher  438  and the unloading pusher  450 . For the rest, this fourth embodiment is identical with the first embodiment illustrated in the  FIGS. 1   a  through  1   f  and described herein above. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 List of Numerals: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 Freeze drying plant 
               
               
                   
                 12 
                 Chamber 
               
               
                   
                 14 
                 Opening 
               
               
                   
                 16, 216, 316 
                 Tray 
               
               
                   
                 18, 218, 318 
                 Vial 
               
               
                   
                 20, 220, 320 
                 Transfer table 
               
               
                   
                 22, 322 
                 Guiding element 
               
               
                   
                 22′, 322′ 
                 Guiding element 
               
               
                   
                 24, 424 
                 Outer groove 
               
               
                   
                 26, 426 
                 Inner groove 
               
               
                   
                 28 
                 Connecting groove 
               
               
                   
                 30, 230, 330 
                 Pusher chain 
               
               
                   
                 430 
                 Rod 
               
               
                   
                 32 
                 Cylinder 
               
               
                   
                 34 
                 Deflection pulley 
               
               
                   
                 36, 436 
                 Guiding pin 
               
               
                   
                 38, 438 
                 Loading pusher 
               
               
                   
                 238 
                 Pusher 
               
               
                   
                 40 
                 Shelf 
               
               
                   
                 42 
                 Long hole 
               
               
                   
                 44 
                 Centering apparatus 
               
               
                   
                 45 
                 Supporting table 
               
               
                   
                 46 
                 Head 
               
               
                   
                 48 
                 Retaining mechanism 
               
               
                   
                 50, 450 
                 Unloading pusher 
               
               
                   
                 52 
                 Long hole 
               
               
                   
                 54, 454 
                 Pin 
               
               
                   
                 56 
                 Feeding device 
               
               
                   
                 58 
                 Tongs
The subject matter of the disclosure is an apparatus for loading and unloading a tray ( 16) of a freeze drying plant ( 10) with a number of vials ( 18), with a transfer table ( 20) provided upstream of the freeze drying plant ( 10) for receiving temporarily said vials ( 18), and with a pusher apparatus for displacing said vials ( 18) from said transfer table ( 20) to said tray ( 16) or from said tray ( 16) to said transfer table ( 20), said pusher apparatus including a right-handed and a left-handed transport carriage ( 30) and a loading element ( 38). To provide an apparatus for loading and unloading a tray ( 16) of a freeze drying plant ( 10) in which the vials ( 18) are securely transferred with little friction onto the tray ( 16) and back is achieved in that the transport carriages ( 30) are disposed on the transfer table ( 20) and/or on the tray ( 16) so as to form a lateral limitation of the transfer table ( 20) and/or of the tray ( 16) for the vials ( 18) located on the edge of the transfer table and/or of the tray ( 16) to directly abut a transport carriage ( 30) during loading or unloading.