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STATEMENT OF RELATED APPLICATIONS 
   This patent application is the Patent Cooperation Treaty (PCT) Chapter II National Phase application in the United States of International Application No. 
   PCT/EP2003/009205 having an International Filing Date of 20 Aug. 2003 and a Priority Date of 10 Sep. 2002 based and claiming priority on German Patent Application No. 10242208.7, and designating the United States. 
   BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates to a wall element or door element—element—having (lower) castors which can be moved on floor runners which are designed as hollow bodies with a slot running in the longitudinal direction, with the runners being mounted in each case on an adjustable castor carrier and the latter being connected to the element. 
   2. Prior Art 
   Wall elements or door elements of this type are also referred to as sliding walls or sliding doors. They conventionally consist of a supporting frame which runs all the way round and has hollow profiles, predominantly made of aluminium. Castors are fitted to the elements at the bottom and top. The lower castors enter into a slot of a floor runner and can thus be moved along the runner with lateral guidance being ensured. A filling comprising panel elements is conventionally connected to the frame. 
   In order to adapt the wall element or door element to local structural stipulations, vertical adjustability is provided. Since the castors always have to have contact with the floor runners, the element can be raised and lowered relative to the castors. For this purpose, the castor carrier, which is preferably designed as a pivotable lever, is adjustable. With the elements closed on both sides, the castor carrier is actuated from a narrow side of the element, namely is pivoted in order to vertically adjust the element in one or other direction. 
   BRIEF SUMMARY OF THE INVENTION 
   The invention is based on the object of improving wall elements or door elements of the described type with regard to the functionality, in particular of ensuring that the castors are supported on the floor runners. 
   In order to achieve this object, the wall element or door element according to the invention and the (floor) castor carrier are characterized by the following features: 
   a) a securing member is fitted in the region of at least one castor, the said securing member entering with anchoring ends into the runner and securing the element against lifting off, 
   b) the securing member is mounted on an axis of rotation of the castor. 
   The wall element or door element according to the invention is secured against lifting off by the securing member as a result of being anchored in the hollow runner. The securing member is preferably designed as a tilting lever which is mounted pivotably on the axis of rotation of the castor and enters with anchoring ends into the runner in a form-fitting manner. In this case, the anchoring ends are designed as hook-shaped elements having thickened areas or hooking elements at the ends in the runner. 
   The mounting of the securing member (exclusively) on the axis of rotation of the castor means that the securing member is independent of any lifting movements of the element relative to the castor. As a result, the castor carrier, as connecting member between the castor and element, can be designed as a member which can be tilted in a vertical plane and which is actuated via a narrow side of the closed element by a suitable tool. 
   The securing member is constructed in a simple manner and consists, in particular, of plastic. The mounting of the securing member on the axis of rotation of the castor means that the castor unit can be produced in a simple manner and can be fitted in the conventional manner. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristic features of the invention will be explained in greater detail below with reference to the drawings, in which: 
       FIG. 1  shows a lower sub-region of a wall element or door element in side view, 
       FIG. 2  shows a detail II from  FIG. 1  on an enlarged scale, 
       FIG. 3  shows a castor unit together with the runner in a perspective illustration on an even more enlarged scale, 
       FIG. 4  shows the castor unit according to  FIG. 3  in side view, 
       FIG. 5  shows a vertical section through the castor unit according to  FIG. 4  in the sectional plane V-V, 
       FIG. 6  shows the castor unit with a vertical subsection and front view in the lower region. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  shows a lower sub-region of a wall element or door element which has a frame  10  running all the way around. Covering panels  11  are fitted on both sides of the frame  10 , with the result that the wall element or door element is closed on both sides. 
   The wall element or door element can be moved by means of lower castors  12  on a runner  13 , which is fitted on the floor. Two castors  12  are fitted to ends of a lower transverse strut  14  of the frame  10 . 
   The runners  13 , which are fixed on or in the floor, are designed as a hollow profile, namely with a lower flange  15  and two angled supporting profiles  16  which form the actual runner. The supporting profiles  16  have mutually facing runner limbs  17 . A central guide slot  18  is formed between the said runner limbs. 
   The castors  12  are profiled in coordination with the design and size of the runner  13 . A central guide rim  19  running all the way around enters in a fitting manner into the guide slot  18  of the runner  13  and thus effects lateral guidance of the castors  12  and therefore of the wall element or door element. Circular supporting surfaces formed on both sides of the guide rim  19  rest on the runner limbs  17  on both sides of the guide slot  18  and roll along said limbs. The castors are designed in a particular manner with regard to the design of these supporting surfaces  20  or shoulders, namely with an inclination which slopes outwards in each case of the order of magnitude of (approximately) 5°. This slightly inclined design of the supporting surfaces  20  brings about an improvement in the running characteristics of the castors  20 , in particular in such a manner that unevenness in the runners  13  is compensated for. 
   Each castor  12  is connected to the element or to the frame  10  via an adjustable securing means. This involves a castor carrier  21  which is designed, in the example shown, as a U-shaped supporting element, in particular made from correspondingly deformed sheet metal. The castor  12  is positioned between upright supporting limbs  22 . A transversely directed castor axle  23  connects the two supporting limbs  22  to each other. The castor  12  is mounted rotatably on the castor axle  23  by means of a ball bearing  24 . In the present exemplary embodiment, a hub  25  extending between the supporting limbs  22  is fitted on the castor axle  23 . The ball bearing  24  runs on said hub. 
   The castor  12  is connected eccentrically, namely in the region of a lower, edge-side corner, to the castor carrier  21 . In the region of an opposite corner, the castor carrier  21  is connected to the element or to the transverse strut  14 , specifically via an opening  26 . The castor carrier  21  can be adjusted about the castor axle  23 , by a pivoting movement in the present case. The castor  12  always remains in the position bearing against the runner  13 . The pivoting movement of the castor carrier  21  causes the door element or wall element to be raised or lowered relative to the castor  12 . In order to adjust the castor carrier  21 , use is made of an adjusting gear (not illustrated) which can be actuated via a narrow side of the door element or wall element, i.e. via an upright strut of the frame  10 . 
   The door element or wall element is equipped with a permanent means of securing the castor  12  against undesirably lifting off from the runner  13 . Each castor unit  27 , which is formed from the castor  12  and castor carrier  21 , has an anchoring member or securing member  28 . The said member is provided with anchoring members or hooking members which enter into the runner  13  in a form-fitting manner, but with a little play, and, by being supported on the runner limbs  17 , prevent the castor  12  from being lifted off. In the present exemplary embodiment, the securing member  28  comprises a shaped element, in particular made of plastic, comprising a lower web  29  and upright supporting wall  30 . 
   In the exemplary embodiment shown, the securing member  28  has (in side view) a triangular design. In an upper region, the supporting walls  30  are connected centrally to the castor unit  27 , specifically to the castor axle  23 . The securing member  28  is accordingly connected to the castor carrier  21  exclusively via the castor axle  23 . For this purpose, the securing member  28  has two supporting walls  30  which are arranged at a distance from each other, are positioned between the supporting limbs  22  of the castor carrier  21  and are mounted on the hub  25  by means of a corresponding opening. For this purpose, the hub  25  is formed at its ends with a step, in the region of which the supporting walls  30  are mounted on the hub  25 . 
   The castor  12  can accordingly be rotated freely irrespective of the position of the securing member  28 . The securing member  28  acts in the manner of a rocker. The anchoring members, which enter with a thickened area into the runner  13 , are fitted at the ends, namely at the ends of the web  29 . In the present exemplary embodiment, two securing hooks  31 ,  32  are provided in each case and are anchored in a form-fitting manner in the runner  13  by means of hook-like projections  33 . The projections  33  of the two securing hooks  31 ,  32  are directed to different sides. 
   This design of the castor unit  27  with securing member  28  ensures that the door element or wall element can be moved up and down without any effect on the position of the securing member  28 . 
   List of Reference Numbers 
   
       
         10  Frame 
         11  Covering panel 
         12  Castor 
         13  Runner 
         14  Transverse strut 
         15  Flange 
         16  Supporting profile 
         17  Runner limb 
         18  Guide slot 
         19  Guide rim 
         20  Supporting surface 
         21  Castor carrier 
         22  Supporting limb 
         23  Castor axle 
         24  Ball bearing 
         25  Hub 
         26  Opening 
         27  Castor unit 
         28  Securing member 
         29  Web 
         30  Supporting wall 
         31  Securing hook 
         32  Securing hook 
         33  Projection

Summary:
A door or wall element comprising castor carriers ( 21 )having castors ( 12 )which are movable on a runner ( 13 ) and securing members ( 28 ) having securing hooks ( 31, 32 ) which are disposed in the runner ( 13 ) and prevent the castors ( 12 ) from undesirably lifting off from the runner ( 13 ). The securing members ( 28 ) are mounted rotatably on castor axles ( 23 ) of the castors.