Patent Publication Number: US-8117670-B2

Title: Variable volume container unit hoisting device for lowering and raising a telescopical expansion element

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a divisional application of U.S. application Ser. No. 10/834,136, filed Apr. 29, 2004, which claims priority under 35 U.S.C. §119 to German Patent Application Nos. 103 56 454.3, filed Dec. 3, 2003 and 10 2004 007 297.3, filed Feb. 14, 2004, the entire disclosure of which are herein expressly incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an expandable container, e.g., according to ISO standards, in particular as a working space, also known as shelters in English-speaking countries. 
     For example, an expandable container is described in German Utility Model 92 16 314.9 and includes a basic container with hinged side panels and one or more expansion elements that can be telescoped out of the basic container. An expansion element includes two side panels and a front panel. In the condition with the expansion element telescoped out, two side panels swung out on the basic container form the roof panel and the bottom panel of an expansion element. One disadvantage of this embodiment is the great sealing lengths required to seal the container along the roof panel and the bottom panel. This is a problem in particular with regard to the requirement for ABC tightness. 
     Another expandable container is known from EP 0 682 156 B1. This includes a basic container and one or more expansion element, which can be telescoped out of the basic container to expand the interior. The expansion elements are box-shaped and except for the side open toward the basic container are closed on all sides. To achieve a flat bottom inside the entire container, a hoisting device is provided to lower the expansion elements to such an extent that after being lowered, the bottom panels of the basic container and of the expansion element are at the same level. In the embodiment having two expansion elements, the dimensions of the two expansion elements must be selected so that the one expansion element can be retracted into the other expansion element. 
     DE 101 35 226 A1 describes a generic expandable container having a hoisting device to achieve a flat bottom. The expansion elements can be lowered with this hoisting device, so that after being lowered, the bottom panels of the basic container and the expansion element are at the same level. The expansion elements are open at the top. The basic container has a side panel that is hinged about a horizontal axis and forms the roof panel of an expansion element when said expansion element is telescoped out. An improved standing height in an expansion element can be achieved with this construction. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to create an expandable container, which has first an adequate standing height even in the expansion elements and second has an easy-to-operate and mechanically sturdy hoisting device. 
     This object has been achieved by providing a hoisting device which acts on the hinged side panel to lower and raise an expansion element. 
     According to the present invention, a mechanism which is already present on the container, i.e. one side panel of the basic container, can be pivoted about a horizontal axis so that when raised, it can also be used as a roof panel of an expansion element to lower the expansion elements, so that a uniform bottom level is obtained in the entire container. To this end, a hoisting device is configured as a linear actuator in particular to act on the hinged side panel. This linear actuator may support itself both on the basic container and on the foundation on which the container is located. 
     To prevent tilting of the expansion element in the pivoting movement of the side panel created by the hoisting device, an equalizing device is provided in a currently preferred embodiment of this invention. This permits parallel lowering, i.e., without tilting the expansion element out of the vertical. The bottom of the expansion element remains horizontal during this lowering operation. 
     In a further embodiment, an expansion element has multiple upper and multiple lower sliding or rolling elements, e.g. rollers, on its inner end (i.e., the end which comes to rest neighboring the basic container when the expansion element is telescoped). Furthermore, the basic container has multiple guide elements assigned to the upper sliding or rolling elements, the elements having ramps slanting downward toward the expanded expansion element on its end neighboring the relevant expansion element (when the expansion element is telescoped). In addition, the basic container has multiple lower stop, assigned to the sliding or rolling lower elements in the form of vertical profile strips, e.g., on its end neighboring the expansion element (when the expansion element is telescoped). If the expansion element is telescoped completely, it assumes a statically fixed, stable position in which the lower sliding or rolling elements stop on the assigned lower stops and the upper sliding or rolling elements rest on the ramps of the guide elements. This stable position forms the starting position for lowering the expansion element by actuating the hoisting device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a ) through  e ) are elevational, cross-sectional schematic views showing the sequence of unfolding a container according to the present invention in five steps; 
         FIG. 2  is a vertical sectional view through a first embodiment of the container of the present invention having a retracted expansion element; 
         FIG. 3  is a vertical sectional view through the first embodiment of the container shown in  FIG. 2  but having an expansion element telescoped out and lowered; 
         FIG. 4  is a sectional view along line  4 - 4  in  FIG. 2 ; 
         FIGS. 5   a  and  5   b  are vertical sectional views through other embodiments of the container of the present invention; 
         FIG. 6  is a partial view of the container shown in  FIGS. 5   a  and  5   b  in direction Z in  FIGS. 5   a  and  5   b;    
         FIG. 7  is a horizontal sectional view along line  7 - 7  in  FIG. 5 ; 
         FIGS. 8   a - 8   c ,  9   a - 9   c ,  10   a - 10   c  and  11   a - 11   c  are sketches of the sequence of lowering an expansion element according to the second embodiment of the container shown in  FIGS. 5   a  and  5   b;    
         FIG. 12   a  is a side view of a container according to the present invention with the expansion element telescoped out and lowered, and  FIGS. 12   b  and  12   c  illustrate additional surface elements. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIGS. 1   a ) through  e ) show the individual steps in construction of an expandable container according to the present invention having two expansion elements  10 ,  20 .  FIG. 1   a ) shows the starting state (i.e., shipping state). The box-shaped basic container  1  contains the two expansion elements  10 ,  20  (see  FIG. 1   d )). The expansion element  20  is retracted into the expansion element  10  which is slightly larger with regard to length and height. A bottom panel  15 ,  25  and front panel  16 ,  26  of the two expansion elements  10 ,  20  and a side panel  27  of the interior expansion element  20  can be seen on each side. The basic container  1  has a bottom panel  2 , a roof panel  3  and two hinged side panels  4 ,  5 , each of the hinged panels mounted to rotate about a horizontal axis  41 ,  51  on the upper edge of a container panel. 
     In  FIG. 1   b ) the two hinged side panels  4 ,  5  have been raised up and are now essentially in one horizontal plane. The side surface of the basic container  1  and the raised side panel  4 ,  5  form a right angle. In this position, the raised side panels  4 ,  5  are supported on a hoisting device  55 , which is a support in the form of a linear actuator and which is variable in length and is arranged with its other end on the basic container  1 . The hoisting device  55  can be configured, for example, as a telescopable hoisting cylinder (e.g., hydraulic, pneumatic, electro-mechanical). 
       FIG. 1   c ) shows the smaller expansion element  20  already completely extracted. This is accomplished by rollers  23 ,  24  provided on the expansion element  20  ( FIG. 3 ) in the upper area of the side panel of an expansion element. These rollers engage in the guide rails  80  (see also  FIG. 2 ) which are provided on the raised side panel  5 . Two guide rails are advantageously provided for each expansion element. In addition, the bottom area of the expansion element  10 ,  20  has additional rollers  21  which roll on the bottom panel  15  of the larger expansion element  10  when telescoped out. When raised, the side panel  5  of the basic container  1  then forms the roof panel of the expansion element  20 . The raised side panel  4  or  5  is therefore also referred to below as a roof panel, depending on the context. 
     In  FIG. 1   d ), the larger expansion element  10  is also completely extracted via the guide rails  80  provided on the raised side panel  4 . The two expansion elements were each telescoped out in the horizontal direction, i.e., without any change in the vertical. The bottom levels of the expansion element  10 ,  20  and the basic container  1  are thus different from one another, with the bottom level of the basic container  1  being the lowest and the bottom level of the small expansion element  20  being the highest. For example, the difference in level of the smaller expansion element from the basic container amounts to approx. 100 mm and the difference in level of the larger expansion element  10  from the basic container  1  amounts to approx. 50 mm. 
       FIG. 1   e ) shows the completely unfolded container with the expansion elements  4 ,  5  lowered, so that now a uniform bottom level is established within the entire expanded container. To do so, the length of the hoisting device  55  assigned to the respective expansion element has been reduced ( FIG. 1   d )). The roof panels  4 ,  5  are therefore mounted so they can rotate about the horizontal axis  41 ,  51  and are pivoted downward out of their horizontal position. In order to prevent tilting of the expansion element  20 , which is connected to the roof panel  4 , 5  via the guide rails, according to a first embodiment of this invention, an equalizing device is provided, to be explained in detail later with reference to  FIGS. 2 through 4 . With a vertical change in position (due to the change in length of the hoisting device  55  of the exterior end of an expansion element, this equalizing device mediates or undergoes a preferably equally great vertical change in position of the end of the expansion element  10 ,  20 , which is on the inside and adjacent the basic container  1 . As a result, a parallel lowering may thus be achieved in which the bottom surface of the expansion element  10 ,  20  is oriented horizontally during the lowering operation and in particular is oriented horizontally on reaching the end position. 
     An important advantage is that only the respective hoisting device  55  need be operated in order to lower the bottom panel. The mechanism for achieving the parallel lowering is coupled to the movement of the hoisting device  55  and thus takes place automatically without any further external intervention. 
     Reference is made to  FIG. 2  for a more detailed explanation of the lowering mechanism according to the first embodiment of this invention. This figure illustrates a vertical section through a container according to the present invention showing the basic container  1  with an expansion element  20  completely retracted into it. The hinged side panel  5  of the basic container  1  has been raised from its vertical shipping state position to a horizontal position about the fulcrum  51 . A guide rail  80  can be seen on the raised side panel  5 . The guide rail is divided into two sections  80   a ,  80   b  which are connected by a hinge  85 . By way of the hinge  85 , the section  80   a  which is on the inside (i.e., adjacent to the basic container  1 ) can be rotated downward. The section  80   b , which is on the outside (i.e., in the direction of the outer edge of the unfolded container), is rigidly connected to the side panel  5 . On the upper edge of its associated side panel, the expansion element  20  has a roller  23  which engages in the guide rail  80  when the expansion element has been telescoped out.  FIG. 2  shows this roller in dash lines in its starting position before the expansion element  20  is telescoped out. At the outer end of the guide rail, the end position of the roller is shown with dot-dash lines, with the expansion element  20  completely telescoped out. Another roller  24  is at the same height on the rear end (not shown in  FIG. 2 ) of the expansion element (see  FIG. 3 ). 
     In addition, the expansion element  20  has bottom rollers  21 , which roll on the bottom panel  15  of the larger expansion element  10  when telescoped out. The longitudinally adjustable hoisting device  55  acts approximately in the middle of the raised side panel  5 . At its other end, this support is supported on the basic container  1 . 
     The equalizing device, which prevents the expansion element from tilting when lowered by the hoisting device  55 , includes a cable  57 , made, for example, of steel. It is connected at one end to the outer end of the guide rail  80  or, alternatively to the side panel  5 . The cable  57  is guided over a pulley U 1  in the lower area of the basic container  1  and from there over another pulley U 2  in the upper area of the basic container  1  above the fulcrum  51  and is attached to the hinged section  80   a  of the guide rail  80  at fastening point B 2 . 
     The length of the cable is adjusted so that, with side panel  5  raised as shown in  FIG. 2 , the hinged section  80   a  of the guide rail  80  is aligned horizontally, with no bend in the hinge  85 . The cable is advantageously acted upon by a tension device with a prestress. The expansion element  20  can then be telescoped out via the rollers  23 ,  24  ( FIG. 3 ), which roll on the guide rails  80 . With the expansion element  20  completely telescoped out, the two rollers  23 ,  24  come to rest in the area of the beginning and end, respectively, of the guide rail  80 . One roller  23  thus comes to lie on section  80   b , which is rigidly connected to the raised side panel  5 , while the other roller  24  comes to lie on the section  80   a  of the guide rail that is folded down in relation to section  80   a.    
     For lowering the expansion element  20 , the hoisting device is operated, i.e., the length of the hoisting device  55  is reduced. The side panel  5  together with the side of the expansion element  20  on the outside pivots downward about the fulcrum  51 . Due to the resulting change in distance of the fastening point B 1  of the cable  57  from the lower pulley U 1 , a corresponding cable length is released on the other end of the cable. This results in the hinged section  80   a  of the guide rail  80  in which the one guide roller  24  of the expansion  20  engages, also being lowered downward together with the interior end of the expansion element  20 .  FIG. 3  shows the container in the state with the expansion element  20  telescoped out and lowered. 
     By adaptation, specifically (1) of the position of the lower pulley U 1  in relation to the outer fastening point B 1  of the cable  57 , (2) of the position of the fastening point B 2  of the cable  57  on the hinged section  80   a  of the guide rail, and (3) of the position of the hinge  85  for the pitch of the guide rail  80 , the vertical change in position experienced by the exterior end of the expansion element  20  is made just equal to the vertical change in position experienced by the interior end of the expansion element  20 . A strictly parallel lowering of the expansion element  20  can thus be achieved without it being tilted out of the horizontal. The bottom  25  of the expansion element is in a horizontal position during the entire lowering movement, in particular on reaching its end position. 
     The direction of movement of the expansion element  20  is essentially vertical at this stage. The horizontal movement executed by the expansion element  20  on the basis of the fact that the exterior end of the pivotable roof  5  is moving on a circular path about the axis  51  can be disregarded if the radius of the pivoting movement (e.g., the width of the expansion element  10 ,  20  in the case of ISO containers is several meters) and a typical objective of approx. 100 mm for the lowering are taken into account. 
     The lowering movement described above is completely reversible. In raising the expansion element  20 , the above-described mechanism described here is run through in a reverse chronological sequence. For raising, the hoisting device  55  is actuated causing a change in length of the support. The roof panel  5  pivots upward about the axis  51 . The resulting change in position of the fastening point B 1  of the cable  57  on the outer end of the roof panel  5  results in the hinged section  80   a  of the guide rail  80  and thus the inside of the expansion element  20  being raised. A parallel raising thereby results without tilting out of the vertical. When the roof panel  5  has reached a horizontal position, the hinged section  80   a  of the guide rail  80  is in contact with the roof panel  5 . The expansion element  20  can then be inserted into the basic container  1 . 
     To ensure accurate vertical and parallel lowering in cases, additional guide devices  99  may be mounted on the basic container  1 . They may be in the form of a rail running vertically, in which the pins  98  ( FIG. 4 ), pegs or bolts that are connected to an expansion element  10 ,  20  engage. 
     Diagonal tension braces  101  can also be mounted for tension release of the hoisting device  55  when the expansion elements  10 ,  20  are telescoped out. In a particularly advantageous embodiment, the tension braces may be configured as cables, so as to be mounted permanently (when the expansion element is retracted as well as when it is telescoped out and also in the transitional phase) on the diagonally opposing mounting points between an expansion element  10 ,  20  and the basic container  1 . 
     When telescoped out, the cables  1010  define the maximum horizontal telescoping path of an expansion element  10 ,  20 . They also ensure correct alignment of the expansion element (no tilting of the expansion element out of the vertical) when the expansion element is completely lowered. When the expansion element is retracted, the cables  1010  are in a niche between the side panel  27  of an expansion element and the basic container  1 . 
       FIGS. 5   a  through  11   c  show a second embodiment of the container according to the present invention which, in contrast to the first embodiment shown in  FIGS. 2 through 4 , a cable or other equalizing device is unnecessary for lowering the interior end of an expansion element. 
     The basic container  1  is shown in  FIGS. 5   a  and  5   b  with expansion element  20  telescoped out. The solid lines show the state before the expansion element  20  is lowered, the dashed lines show the state with the expansion element lowered. The hoisting device  55  is implemented, as in the first embodiment shown in  FIGS. 2 through 4 , as a linear actuator which acts on the hinged side panel  5  to achieve lowering and raising of the expansion element  20 . 
     Two variations are shown in  FIGS. 5   a  and  5   b  with regard to the support of the hoisting device  55  acting as a linear actuator. According to the first variation, the hoisting device  55  acting as an actuator is supported on the basic container  1 . Alternatively, the hoisting device  55  acting as an actuator can be supported on the foundation on which the container is located. Support of the hoisting device  55  on the foundation is also contemplated for the first embodiment of the container shown in  FIGS. 2 through 4 . 
     In the embodiment shown in  FIGS. 5   a  and  5   b , the two functions of (a) raising the side panel  5  from its vertical starting position ( FIG. 1   a ) into its horizontal position ( FIG. 1   b )) around joint or fulcrum  51  ( FIG. 6 ); and (b) lowering the expansion element  20  are also assigned to different hoisting devices. There is also a second linear actuator  56  which folds up the side panel and acts between the basic container  1  and the hinged side panel  5 . The other hoisting device  55  is specifically responsible for the lowering and raising of the expansion element  20 . In accordance with the different operating loads, the actuator  56  may be configured as weaker than the hoisting device  55  acting as an actuator. Such a division of the two functions to different hoisting devices is also contemplated in the first embodiment of the inventive container shown in  FIGS. 2 through 4 . 
     During telescoping, the expansion element  20  is guided in the guide rail  180  on precisely one point, namely roller  123 . The expansion element is rotatable around a horizontal axis D on this point. This roller  123  is positioned in a region extending in the horizontal direction between the center of gravity S of the expansion element  20  and the exterior end of the expansion element  20 . 
     The expansion element  20  also has an upper roller  201  and a lower roller  202  on its interior end neighboring the basic container. The two rollers  201 ,  202  are each attached via a shaft receiver  205  ( FIG. 6 ) to a side panel of the expansion element  20 . The upper roller  201  is associated with a guide element  211 . The guide element  211  is positioned on the top of the basic container  1 , on an end neighboring the expansion element  20 . The element  211  has the shape of an angle with horizontally and vertically aligned legs and a ramp connecting the two legs, which ramp slopes down toward the expansion element  20 . The ramp has a horizontal length of 10 mm in a typical embodiment. Preferred angles are in the range from 20 to 50 degrees in relation to the vertical. 
     The lower roller  202  is assigned a stop  212  positioned on the basic container  1  on its end neighboring the expansion element  20 . The stop  212  has the shape of an essentially vertically running profile which runs over nearly the entire height of the basic container  1  in this illustrated embodiment. 
       FIGS. 5   a ,  5   b  and  7  show the rollers  201 ,  202 , positioned on a side panel  27  of the expansion element  20 . Of course, corresponding rollers are provided on the diametrically opposing side panel of an expansion element  20 , and work together with a guide element and a vertical stop provided on the other side of the basic container.  FIG. 7  is a horizontal sectional view along line  7 - 7  of  FIG. 5   a , in which the upper roller  201  and guide element  211  and stop profile  212  are illustrated in detail. Upper roller  201  and lower roller  202  are illustrated in  FIGS. 5   a ,  5   b  and  7 , each in their position with expansion element  20  lowered completely. 
     As will be described in greater detail later with reference to  FIGS. 8   a - 11   c , the rollers  201 ,  202  and the guide element  211  and stop  212  associated therewith provide a statically fixed position for the expansion element  20  and can be used as a starting position for the lowering operation. In this starting position, the lower roller  202  is supported on the stop  212 , and the upper roller  201  is supported on the ramp of the angular guide element, so that the tilting moment induced by the weight (center of gravity S) is absorbed around the fulcrum D. 
     After the expansion element  20  has been completely lowered, the hoisting device  55  can be dismounted and stowed in a niche of the basic container  1 . In the telescoped and lowered state of the expansion element  20 , the loads of the expansion element  20  are advantageously absorbed by the stop  212 , on which both the lower and the upper roller  201 ,  202  are supported. Alternatively or additionally, the operating loads can be absorbed by a tension brace  101  between basic container  1  and the expansion element  20  when expansion element  20  is telescoped and lowered as illustrated in  FIGS. 5   a  and  5   b.    
     In a particularly advantageous embodiment, the tension brace  101  is implemented as a cable that is permanently attached to the diagonally opposing attachment points between an expansion element  20  and the basic container  1  (both with the expansion element retracted and with the expansion element telescoped, and in the transition phase). When the expansion element is retracted, the cable  101  is located in a niche between the side panel  27  of an expansion element  10 ,  20  and the basic container  1 . 
       FIGS. 8   a - 11   c  show the sequence of lowering an expansion element for the embodiment of the container illustrated in  FIGS. 5   a  through  7 . In each of  FIG. 8   a - 11   c , the regions around the upper guide element  211  and the lower stop  212  are also shown enlarged in the isolated memo. 
     As the expansion element  20  is telescoped out of the basic container  1 , it rolls on bottom rollers  21  which positioned on its bottom panel  25 . The bottom rollers  21  roll on the bottom panel  15  of the larger expansion element  10  ( FIG. 1 ), which is not located completely in the basic container  1 . In addition, the expansion element  20  is guided by the roller  123  in the guide rail  180  which is attached to the raised side panel  5  where it is mounted to rotate around a horizontal axis or fulcrum point D. The raised side panel  5  is in a horizontal position during the telescoping. 
       FIGS. 8   a - c  shows the expansion element  20  almost completely telescoped out. The last of the bottom rollers  21  has reached the outermost edge of the bottom panel  25 . The load is now taken by the guide element  211  positioned on top of the basic container  1 . The upper roller  201  positioned on the expansion element  20  now lies on the horizontal leg of the guide element  211 . 
     If the expansion element  20  is telescoped out even further as seen in  FIGS. 9   a - 9   c , the upper roller  201  reaches the ramp of the guide element  211  which slopes outward. Because of the torque, in relation to the fulcrum D, induced by the weight of the expansion element (center of gravity S), the upper roller  201  rolls on the ramp of the guide element  211  until the lower roller  202  positioned on the expansion element  20  stops on the vertical stop  212  of the basic container  1 . The expansion element is now located in a stable, statically-fixed position (i.e. geometrically clamped), in which the roller pair  201 ,  202  generates a countertorque having the same absolute value as the torque induced by the weight of the expansion element  20 . This stable position, which is illustrated in  FIGS. 9   a - 9   c , forms the starting position for lowering the expansion element. The raised side panel  5  is still in a horizontal position as before. 
     With reference to  FIGS. 10   a - 10   c , the expansion element  20  is now lowered by actuating the hoisting device  55  ( FIGS. 5   a  and  5   b ) which acts on the raised side panel  5  and pivots it downward around the fulcrum  51 . At the same time, the lower roller  202  rolls downward on the vertical stop  212 . The upper roller  201  also rolls downward on the guide element  211 , via the ramp, and then on the vertical leg of the guide element  211  until the completely lowered position of the expansion element  20  is reached as shown in  FIGS. 11   a - 11   c.    
     Those skilled in the art will recognize that the lower stop  212  and the leg of the guide element  211  do not necessarily have to be aligned exactly vertically. Reliable lowering is possible even if these two elements cited are tilted out of the vertical. Likewise, it will also be apparent to those skilled in the art that, in order to reduce the surface pressure a single roller  201 ,  202  may also be replaced by a group of rollers, e.g., two or three rollers which are positioned on a shared frame. Instead of the rolling elements  201 ,  202 , sliding elements can also be used. For example, a pin having a rectangular cross-section can be used as a sliding element, one of its surfaces being implemented as a sliding surface (e.g., using a slide coating). 
     The lowering movement described is completely reversible. By actuating the hoisting device  55  (i.e., extending the linear actuator), the expansion element  20  is raised until it reaches the stable position shown in  FIGS. 9   a - 9   c . From this position, the expansion element  20  is retractable into the basic container  1 . 
     After the lowering operation is concluded, trapezoidal openings  95  are formed between the upper edge of the side panel and the roof panel  4 ,  5  with the expansion elements  10 ,  20  as previously described with reference to  FIG. 1   e ). To close these openings, additional trapezoidal surface elements  18 ,  28  may be collapsibly mounted on the upper edge of the side panels  17 ,  27 . After the expansion elements have been completely telescoped out and lowered, they can be raised, as illustrated in  FIGS. 12   a - 12   c  so that openings between the roof panel  4 ,  5  and the side panel  17 ,  27  are now closed. The unfolding process is illustrated in detail in  FIGS. 12   b  and  12   c , which are illustrations of the isolated portions taken along lines B-B and A-A of  FIG. 12   a . Thus, a container interior is formed which is completely closed to the outside. Instead of being mounted on the upper edge of the side panels, the additional surface elements can also be collapsibly mounted on the roof panel  4 ,  5  of an expansion element  10 ,  20 . 
     In a further embodiment, the additional surface elements can be integrated into the side panels of an expansion element, so that the side panels are implemented as double-paneled and the additional surface element is positioned between the two panels of the side panel. If necessary, the additional surface elements can be telescoped out using, for example, a spring force. For this purpose, reference is again made to  FIGS. 8   a - 11   c  where an additional surface element  128  is integrated into the side panel there. When the gaps between side panel and roof panel  5  arise as the expansion element  20  is lowered, the additional surface element  128  automatically telescopes out of the side panel and closes the momentarily existing gap. As seen in  FIGS. 8   a - 8   c , the additional surface element  128  is still positioned completely inside the side panel at the beginning of lowering. When the expansion element  20  is completely lowered, the additional surface element  128  is also maximally telescoped out of the side panel. 
     In another contemplated embodiment, the additional surface elements may be configured with double panels. For sealing purposes, gaskets, such as contact gaskets, can be provided on the additional surface elements or on the basic container or the expansion elements  10 ,  20 . The additional surface elements  18 ,  28  can also be structurally separate from the container elements and shipped as separate components, which are inserted as needed. 
     The examples illustrated in the drawings show embodiments having exactly two expansion elements. Embodiments having exactly one or more than two expansion elements are of course also contemplated. The telescoping operation and the lowering operation take place like the processes depicted here for the individual expansion elements  10 ,  20 . 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.