A device for bridging a difference in height between two floor surfaces ( 1, 3 ) is described, with said device comprising a profiled cover ( 4 ) that is provided with a covering flange ( 5 ) which covers the edge of each of the two floor surfaces ( 1, 3 ), with at least one clamping extension ( 6 ) that protrudes downward from the covering flange ( 5 ), extends longitudinally with respect to the profiled cover ( 4 ), and clamps into and engages with a fixture ( 7 ), with said device also comprising a compensating strip ( 10 ) located between the covering flange ( 5 ) of the profiled cover ( 4 ) and the lower of the two floor surfaces ( 1, 3 ). In order to create advantageous construction conditions it is proposed that the fixture ( 7 ) forms a clamping seat ( 11 ) for the compensating strip ( 10 ).

CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 10/590,949 filed on Nov. 8, 2006, which application is a national stage application under 35 U.S.C. §371 of PCT Application No. PCT/AT2005/000017 filed Jan. 25, 2005 which claims priority under 35 U.S.C. §119 from Austrian Patent Application No. A 318/2004 filed Feb. 27, 2004, the disclosures of each of which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a device for bridging a difference in height between two floor surfaces, with said device comprising a profiled cover that is provided with a covering flange which covers the edge of each of the two floor surfaces and at least one clamping extension that protrudes downward from the covering flange, extends longitudinally with respect to the profiled cover, and clamps into and engages with a fixture. The said device also comprises a compensating strip located between the covering flange of the profiled cover and the lower of the two floor surfaces. 
     2. Description of the Prior Art 
     A known method for bridging steps or joints in floor coverings is disclosed in WO 99/01628 A1, wherein profiled covers for steps and joints are invisibly attached by means of fixtures. For this purpose, the fixtures consist of a profiled section with a flat horizontal fastening element on the floor side. Extending upward from this flat horizontal element are vertical retaining legs, between which the downwardly protruding clamping extension of the profiled cover is inserted and held in place. In order to bridge height differences between adjacent floor coverings, a hollow cavity is formed adjacent to and along the length of the clamping extension of the metallic profiled cover, allowing the flange of the profiled cover that extends from the clamping extension to bend in such a way that the angle of flex of the profiled cover can adjust to the height difference between the floor coverings to be bridged in each case. 
     Such an adjustment for height differences with respect to the floor coverings being bridged requires the profiled covers to have the requisite flexural properties, which for instance timber building materials do not possess. In order to facilitate a height adjustment between two floor coverings using timber materials accordingly, without the necessity of using various profiled covers, WO 03/040492 A1 discloses a profiled cover with a compensating strip arranged on the low floor side. This compensating strip is provided with an undercut groove for attachment to the underside of the covering flange of the profiled cover. The purpose of the groove is to accommodate a projection on the underside of the covering flange parallel to the clamping extension of the profiled cover in a form-fitting manner. The primary disadvantage of this known device for bridging a difference in height between two floor surfaces is that the projection on the underside of the covering flange hinders the manufacture of the profiled cover and that it is virtually impossible to achieve a form-fitting joint between the profiled cover and the compensating strip due to the unavoidable manufacturing tolerances resulting from the separate production of the profiled cover and the compensating strip. Moreover, the profiled cover can only be used without a compensating strip as a cover for an expansion joint between two level floor coverings if the projection on the underside of the covering flange is removed beforehand. 
     SUMMARY OF THE INVENTION 
     Consequently, the object of the invention is to develop a device for bridging a difference in height between two floor surfaces of the aforementioned type that is able to fulfill the requirements for the exact fit of a profiled cover and compensating strip, while still being simple to manufacture. 
     The invention fulfills this object by means of the fixture forming a clamping seat for the compensating strip. Consequently, as the resultant fixture for accommodating the clamping extension of the profiled cover also creates a clamping seat for the compensating strip there is no need for a form-fitting joint between the profiled cover and the compensating strip. This not only facilitates the manufacture of the profiled cover, but also of the compensating strip as there is no provision of a projection on the underside of the covering flange of the profiled cover nor the provision of a longitudinal groove in the covering strip. The absence of a projection on the underside of the cover flange of the profiled cover also means that the profiled cover can be used to bridge expansion joints between level sections of floor, without having to perform additional work on the profiled cover. 
     The fixture for the profiled cover and also for the compensating strip can be designed differently as the only important thing is to have corresponding clamping joints to ensure the reciprocal spatial correspondence of the profiled cover and the compensating strip. However, construction is particularly simple if the fixture consists of a known profiled section with resilient retaining legs protruding upwardly from a mounting plate for clamping the clamping extension of the profiled cover. The mounting plate on the low floor side extends past the retaining leg and bears the clamping seat for the compensating strip, which only needs to be pushed onto the clamping seat before the profiled cover with the clamping extension is clamped firmly between the retaining legs and the covering flange rests on the compensating strip. It is advantageous if the clamping seat for the compensating strip can be developed as a retaining leg engaging with a longitudinal channel in the compensating strip, with said leg firmly holding the profiled cover clamped in the profiled section of the fixture transversely to its longitudinal axis. In addition, the covering flange of the profiled cover for the compensating strip can form an abutment on the clamping extension side so that the local clamping extension forms an abutment such that the profiled cover and the compensating strip are not only held in position by the fixture, but also directly by the abutment. 
     With the retaining leg serving as a clamping seat there is the advantage that the compensating strip lies against the abutment of the covering flange due to the resilient pretensioning of the retaining leg, facilitating compensation of manufacturing tolerances. If the profiled cover is employed without the compensating strip, for instance to bridge an expansion joint, the widened part of the mounting plate of the fixture can hinder its placement inside the expansion joint. For this reason the section of the mounting plate extending beyond the retaining leg can be removed from the remaining mounting plate by means of a predetermined breaking point. 
     The underside of the covering flange without the projection is an essential requirement for a simple manufacturing process with respect to the profiled cover and the compensating strip. This manufacturing process is characterized in that initially a common profiled section is produced, the cross-section of which is formed from the cross-section of the profiled cover and at least one adjoining compensating strip, including machining allowances for kerfing on the underside of the covering flange on the one hand and on the lateral surface of the clamping extension on the other. Then the compensating strip is separated from the profiled cover by cutting along the underside of the covering flange and the lateral surface of the clamping extension. By manufacturing the profiled cover and the compensating strip from a common profiled section with separating cuts along the underside of the covering flange on the one hand and along the lateral surface of the clamping extension on the other, not only can the material for the profiled cover and the compensating strip be utilized advantageously, but also the precision of fit increased enormously as the deviations from the specified cutting plane for the profiled cover and the compensating strip correspond to each other when the profiled cover and the compensating strip are mated, allowing the profiled cover and the compensating strip to be joined without any play. 
     Although the profiled section can be limited to the simultaneous production of the profiled cover and a single compensating strip, it can be advantageous to cut two differently shaped compensating strips from one common profiled section with one profiled cover. This can be done if a common profiled section is initially manufactured for one profiled cover and one compensating strip for each side of the clamping extension, before the two compensating strips are separated from the profiled cover by means of a cut along the underside of the covering flange and along each side of the clamping extension. This provides two compensating strips for one covering strip, to be employed as required. 
     Manufacturing the profiled cover and the compensating strip or strips at the same time provides additional advantages for coated profiled covers and compensating strips as the structure and appearance of the coating of the profiled cover and the compensating strips are identical if the common profiled section is initially coated on what will become the visible side of the profiled cover and the compensating strip or strips, before then being separated into the profiled cover and compensating strip or strips. The difference between the abutting coatings of the abutting profiled cover and compensating strips can at the most involve changes at the kerfs, changes that are visually negligible owing to the minimal kerf widths. 
     If the profiled covers and the compensating strips are coated using droplets, as for instance with spray coating, vacuum deposition or vaporization, the common profiled section can first be cut along the underside of the covering flange and then be coated before the profiled cover and the compensating strip or strips are completely separated by cutting along each lateral surface of the clamping extension. This partial cut prior to coating has for instance the advantage that the partial coating of the cut between the covering flange and the compensating strip coats the longitudinal edges of the profiled cover and the compensating strip, an outcome that is not achieved if cutting is performed afterwards. In order to prevent the creation of a gap between the covering flange and the floor covering under the covering flange when covering the higher of the two floor surfaces, the cut along the underside of the covering flange of the profiled cover can run at an acute angle, requiring the covering flange to be undercut. This undercutting also causes the compensating strip to be centred due to the wedging effect when the profiled cover is subject to load, pressing the compensating strip against the abutment. 
     If the kerfs of the cuts along the underside of the covering flange and the lateral surfaces of the clamping extension only overlap in part of the kerf width, a step is created in the section of kerf overlap that advantageously serves as an abutment for the compensating strip that is pressed against it by the fixture, achieving exact positioning of the compensating strip with respect to the profiled cover. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The drawing illustrates examples of embodiments of the invention. In the drawing 
         FIG. 1  shows a device in accordance with the invention for bridging a difference in height between two floor surfaces in a simplified cross-section, 
         FIG. 2  shows a frontal view of a common profiled section for producing a profiled cover and two compensating strips, 
         FIG. 3  shows a cross-sectional view of the profiled section in accordance with  FIG. 2  after a separating cut along the underside of the covering flange of the subsequent profiled cover in cross-section, and 
         FIG. 4  shows a cross-sectional view of the covering strip produced from the profiled section in accordance with the  FIG. 2  by cutting along the lateral surface of the clamping extension, with the two compensating strips in an arrangement corresponding with the profiled section. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In accordance with the embodiment in  FIG. 1 , a difference in height between a floor surface  1 , for instance a floor covering  2 , and a floor surface  3  requires bridging, with the latter floor surface  3  in accordance with the embodiment being formed by the substrate for the floor covering  2 . The floor surface  3  can of course also be formed by another floor covering. A profiled cover  4  is employed to bridge the difference in height between the floor surfaces  1  and  3 , said profiled cover  4  consisting of a covering flange  5  and a clamping extension  6  protruding downwards from the covering flange  5 , said clamping extension being held and gripped in a fixture  7 . This fixture  7  is developed as a profiled section, having resilient retaining legs  9  protruding upward from a mounting plate  8 , with the clamping extension  6  of the profiled cover  4  being engaged by said legs. 
     As the profiled cover  4  is developed symmetrically with respect to a longitudinal middle plane, the profiled cover cannot bridge the difference in height between the floor surfaces  1  and  3 . Accordingly, to bridge this difference in height, provision is made for a compensating strip  10 , which attaches to the underside of the covering flange  5  of the profiled cover  4  on the side with the lower floor surface  3  and rests on this floor surface  3 . To ensure a flush connection between the compensating strip  10  and the covering flange  5 , without provision having to be made for a form-fitting connection between these structural components, the fixture  7  forms a clamping seat  11  for the compensating strip  10 . To this end, the mounting plate  8  extends past the retaining legs  9  and bears a retaining leg  12  at the longitudinal edge of the extension, said retaining leg  12  being inserted into a longitudinal groove  13  in the compensating strip  10 . The covering flange  5  of the profiled cover  4  forms an abutment  14  in the vicinity of the clamping extension  6  for the compensating strip  10 , which is pressed against this abutment by the resilient pretensioning of the retaining leg  12  of the clamping seat  11 , such that the compensating strip  10  is positioned precisely with respect to the profiled cover  4 . 
     Accordingly, the difference in height between two floor surfaces  1  and  3  is bridged in an advantageous manner with the assistance of the compensating strip  10  in conjunction with a profiled cover  4  that is symmetrical with respect to a longitudinal middle plane, without impinging upon the use of the profiled cover as a cover for an expansion joint in the vicinity of a floor covering that does not differ in height around the expansion joint. This is achieved by fastening the compensating strip  10  by means of the clamping seat  11  of the fixture  7  as in this case a form-fitting connection between the covering flange  5  and the compensating strip  10  is not required. However, the clamping seat  11  of the fixture  7  for the compensating strip  10  does not preclude an adhesive joint between the compensating strip  10  and the adjacent section of the covering flange  5 , which to this end can be provided with an adhesive strip, which is not represented for reasons of maintaining clarity. If the profiled cover  4  is used without the compensating strip  10 , the widened section of the mounting plate  8  with the retaining leg  12  generally hinders positioning of the fixture  7 . Therefore, the widened section of the mounting plate  8  with the retaining leg  12  is provided with a predetermined breaking point immediately adjacent to the profiled section of the fixture  7 , as indicated in  FIG. 1 . Consequently, if required, the retaining leg  12  can be separated from the rest of the profiled section, together with the widened section of the mounting plate  8 . 
     Simply positioning the compensating strip  10  on the corresponding section of the covering flange  5  constitutes an advantageous condition for simple manufacturing of the compensating strip  10  and the profiled cover  4 , as the profiled cover  4  and the compensating strip  10  can be manufactured from a common profiled section in accordance with  FIGS. 2 to 4 . In accordance with  FIGS. 2 to 4  the common profiled section  15  encompasses not only one compensating strip  10 , but also two compensating strips  10  of differing form, something that further expands the application options of the profiled cover  4  thanks to the optional use of either of the two compensating strips  10 . 
     As can be seen in  FIG. 2 , the cross-section of the common profiled section  15  is comprised of cross-sections of the profiled cover  4  on the one hand and the compensating strips  10  on the other, with provision being made accordingly for machining allowances  16  for kerfs between the covering flange  5  and the clamping extension  6  of the cross-section of the profiled cover  4  as indicated by the dash-dotted line and the abutting compensating strips  10 , the outline of which is also indicated by means of dash-dotted lines.  FIG. 3  shows the compensating strips  10  partially separated from the subsequent profiled cover  4  by kerfs  17  along the underside of the covering flange  5 . Complete separation is achieved by cutting along the lateral surfaces of the clamping extension  6 , as indicated by the dash-dotted kerfs  18 . The compensating strips  10  that are completely separated from the profiled cover  4  are visible in  FIG. 4 , specifically in a bilateral arrangement corresponding to the profiled section  15 , on which the device is based. It is demonstrated that the profiled cover  4  and the compensating strips  10  can be produced from the same profiled section  15  by simple, straight cuts corresponding to kerfs  17  and  18 , and in fact with the advantage that unavoidable cutting inaccuracies are compensated when the profiled cover  4  and the compensating strips are placed together. 
     In accordance with  FIG. 3 , the kerfs  17  and  18  only overlap for a section of the kerf width along the underside of the covering flange  5  and along the lateral surfaces of the clamping extension  6  such that a step is produced in the vicinity of the clamping extension  6  of the profiled cover  4 , said step able to serve as an abutment  14  for the corresponding compensating strip  10 . 
     In order to avoid gaps at the edges between the covering flange  5  extending over the floor surface  1  and the floor covering  2 , the covering flange  5  must form an undercut so that the longitudinal edge of the covering flange  5  is reliably supported on the floor covering  2 , as shown in  FIG. 1 . In order to achieve such an undercut during manufacture of the profiled cover  4 , the kerfs  17  only need to run at an acute angle α with respect to the covering flange  5 , as shown in  FIG. 3 . The corresponding inclination of the upper side of the compensating strips  10  formed by the kerfs  17  provides the advantage that the section of the covering flange  5  in the vicinity of the compensating strip  10  is supported across the full surface of the compensating strip  10 . 
     Manufacturing the profiled cover  4  and the compensating strips  10  from a common profiled section  15  also ensures advantageous conditions for coating the visible surfaces of the profiled cover  4  and the compensating strips  10  in a similar manner as the profiled cover  4  and compensating strips  10  can be coated at the same time as part of the profiled section  15 . Differences regarding the surface structure and the appearance of the coating can only occur as a result of changes near the kerfs  17  when the compensating strips  10  are separated from the profiled cover  4  after the common profiled section  15  has been coated. This separation by means of the kerfs  17  can be performed prior to or after coating, depending on the type of coating. Cutting along the kerfs  17  is recommended after coating with a foil for instance in order to achieve the smoothest transition possible between the coating structure and the appearance of the coating between the compensating strips  10  and the profiled cover  4 . On the other hand, in the case of spray coating, for instance varnishing, it is best to cut along the underside of the covering flange of the common profiled section  15  before coating in order to coat the edges producing by the kerfs  17  as indicated by the dot-dashed lines in  FIG. 3 , which indicate the spray coating  19  that extends over the edges and into the kerfed areas.