You are an expert at summarizing long articles. Proceed to summarize the following text:

You are an expert at summarizing long articles. Proceed to summarize the following text: 
No federally sponsored research or development, and no sequence listing, table, or computer program listing compact disc appendix is applicable to this application. 
    
    
     BACKGROUND 
     This disclosure relates to the field of drains for liquid flows, and more particularly to a removable floor drain grating having a mechanism for locking the grating in place over a drain pipe and which is unlocked only by use of a tool so as to prevent casual removal of the grating which may lead to undesired clogging due to drain pipe stuffing, that is, allowing large amounts of materials to enter the drain pipe. The same locking mechanism may be used with a cover for sealing the open end of a drain pipe or any similar pipe when the grating is replaced with a cover plate without any pass-through apertures, i.e., without openings therein. 
     A drain grating or covering is conceived as a plate that may be fitted over a drain pipe or conduit, and which may have plural openings in it, each generally smaller than the span of the drain pipe itself. Its purpose is to prevent large items from entering the drain pipe which may clog it. A grate may also be constructed as a series of spaced apart rigid bars as a lattice or as a screen such as one made of expanded metal sheeting or the like. In general, a drain grate is a filter. Drain grates usually become covered or engaged with the large items which they are designed to prevent from entering the drain pipe so that they must be periodically cleared which may require temporary removal from the drain pipe. In commercial kitchens, floors are generally hosed down to assure meeting cleanliness standards. Items such as foodstuffs, packaging materials, and the like are carried by water flows to floor drains and if allowed to enter the drain pipes, clogs may occur. To prevent this, such items must be removed from the drain grate manually in order to have a free flow of water. Kitchen help may resort to removing a drain grate in order to allow such items to enter the drain pipe thereby shortening kitchen cleanup time. This practice often results in drain pipe clogging requiring expensive steps in clearing such clogs. To help prevent this, a locking drain pipe grating may be used; one that is not easily removed. The prior art discloses various means for locking a cover onto a drain or other cylindrical conduit including types described in the following. As said, such locking mechanisms are equally useful in sealing a cover plate onto the end of a pipe to prevent anything from passing into or out of the pipe. 
     The prior art discloses a ratchet type closet flange for replacing broken cast iron closet flanges in old buildings or in new construction in place of conventional cast iron closet flanges. Such a device includes a flange body, a cup, a rubber seal, and a means for applying pressure such as a central bolt. After removing the broken closet flange, the ratchet type closet flange is inserted into the existing pipe. A compression seal is formed between the flange body and the inside of the pipe by applying pressure to the flange body and the cup using a central bolt, thereby forcing a compression relationship between the rubber seal and the pipe. The ratchet type closet flange may slide up and down inside the pipe to achieve a desired height. 
     The prior art also discloses various drain covers with looking mechanisms including those having a cylindrical body with a peripheral sidewall. Wedge members are movable from a release position to a locking position by use of a central screw or jacking mechanism. In the release position each wedge member is positioned at one end of the peripheral sidewall. In the locking position each wedge member is moved upwardly into contact with an opposing end of the peripheral sidewall so that an exterior surface of the peripheral sidewall wedges within the cylindrical body. 
     The presently described apparatus incorporates an advance over prior art concepts providing a locking grating or sealing cover with novel benefits in manufacture and operation as will be described below. 
     BRIEF SUMMARY AND OBJECTIVES 
     The present disclosure describes an apparatus and method for producing a drain pipe grating and locking system for holding the drain grating in place over the drain pipe. The apparatus Advantages of the presently disclosed subject include 
     The details of one or more embodiments of these concepts are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of these concepts will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  is an example front elevational view of the presently described apparatus as adapted for use in a first application and shown with a partial vertical section of an environment thereof; 
         FIG. 2  is an example bottom perspective view of said apparatus; 
         FIG. 3  is an example bottom perspective view of a grating thereof; 
         FIG. 4  is an example top perspective view of an extender thereof; 
         FIG. 5  is an example bottom perspective view of said extender; 
         FIG. 6  is an example perspective view of an expander of the apparatus, the expander shown with an engagement jacking bolt secured therewith; and 
         FIG. 7  is an example top perspective view of the presently described apparatus as adapted for use in a second application. 
     
    
    
     Like reference symbols in the various views indicate like elements. 
     DETAILED DESCRIPTION 
       FIG. 1  shows the presently described apparatus  10  positioned at one end of, and extending into a conduit  3  which is set into a concrete floor structure. Alternatively, the conduit may be a pipe, a tube or may also be a hollow space within a structure such as a round opening in a concrete wall, ceiling or floor as for example.  FIG. 2  shows a relationship between the several elements of the apparatus  10 , namely: a disc-shaped cover  20 , an extender  40 , an expander  60  and a jacking bolt  80 . The cover  20 , extender  40 , and expander  60  are secured together by the engagement jacking bolt  80  which is centrally positioned and defines a central axis  5  ( FIG. 1 ) about which the several elements are arranged in a linear series as shown. A head  82  ( FIG. 6 ) of jacking bolt  80  is positioned within a recess  22  ( FIG. 7 ) of cover  20  and a shaft  84  of jacking bolt  80  extends downwardly therefrom through elements  20 ,  40 , and  60  whereupon a threaded portion  86  of shaft  84  engages a jacking nut  62  as shown in  FIG. 6  and this holds the several elements of apparatus  10  together as an assembly. 
       FIG. 3  illustrates one embodiment of cover  20  which is used as a drain grate. In this embodiment, cover  20  may have an outside peripheral edge  24 , a top surface  26 , a bottom surface  28 , and a centrally positioned first spline  30 . On the bottom surface  28 , a lip  32  may be positioned adjacent to peripheral edge  24 . Lip  32  may be made up of a plurality of segments  33  with spaces  34  between them as shown so that water may pass into conduit  3  directly from the floor surface  5 . The bottom surface  28  may also have integral near-radially positioned webs  36  extending between the centrally positioned first spline  30  and the peripheral edge  24 . The webs  36  may be formed in relief to the bottom surface  28 . Such webs  36  provide strength to the cover  20 . Furthermore, the cover  20  may have plural openings  38  extending between the top surface  26  and the bottom surface  28 , so that the cover  26  may function as a grating.  FIG. 7  shows the cover  20  in a further embodiment where it is used as a sealing cap over an open end of conduit  3 . In this embodiment there are no openings  38  or perforations. 
     It should be noted, as shown in  FIG. 5 , that first spline  30  has several spline-slots  31 . Four slots  31  are shown but less or more slots  31  may be employed.  FIGS. 4 and 5  show the extender  40  which may be an elongated rod-like solid part with spline-fingers  41  at one end, shown best in  FIG. 4 , and with spline-slots  31  at the opposing end, shown best in  FIG. 5 . It is shown in  FIGS. 1 and 2  that the spline-slots  31  of first spline  30  may be engaged with the spline-fingers  41  of extender  40 . Likewise, identical spline fingers  41  of expander  60  may be engaged with first spline  30 . The spline-slots  31  of cover  20  may be identical to the spline-slots  31  of extender  40 . Therefore, the extender  40  may be left out of the assembly without loss of function and in practice, extender  40  is used to position expander  60  at a selected position within conduit  3 . The term “spline” is used here and is shown in the several figures to define and illustrate one possible means for coupling cover  20  with either extender  40  or expander  60  and also, to couple extender  40  with expander  60 . However, alternate means for coupling these elements may be employed as would be known to those of skill in the art. Therefore the term “spline” is meant to take the broader meaning of “coupling device” in this description and in the following claims. 
       FIG. 6  illustrates the engagement jacking bolt  80  secured within the expander  60 . The expander  60  has a second spline  63 , an elongated tubular portion  64 , a jacking nut receiver  66 , and a pair of opposing flexible C-shaped arms  68 . Each of the arms  68  have plural gripping claws  70  arranged one below the next, as for instance the four claws  70  shown. The claws  70  may have relatively sharp terminal edges  72  for gripping the interior surface of conduit  3 . 
     It should be noted, as shown in  FIG. 1 , that cover  20  is in contact with one end of conduit  3  and may also be in contact with a floor surface  5 ; and that elements  30  and  40  may extend downwardly within conduit  3  to some distance below the floor surface  5 . Extender  40  may be removed from the assembly so that the spline portion of expander  60  may be engaged directly with the spline portion  30  of cover  20  with the result that the ribs  70  will be positioned higher within conduit  3 . Likewise, extender  40  may be made at any selected length and used in the assembly in order to position the ribs  70  at a desired vertical location within conduit  3 . When engagement screw  80  is rotated in a first rotational sense as with the wrench  90  shown in  FIG. 7 , the jacking nut  62  may be drawn upward and the arms  68  will be forced to bow laterally outward into positions shown by broken lines  92 , that is, into contact with the interior walls  4  of conduit  3 . In this case, the sharp claws  72  of ribs  70  tend to grip the walls of conduit  3  thereby locking the assembly within conduit  3 . When screw  80  is rotated in a second (opposite) rotational sense the reverse occurs, that is, the material of which the expander  60  is made has a resiliency that allows the arms  68  to resume their original shape each time tension is removed. In this case, the assembly may be removed from conduit  3 , but may later be again locked in place within conduit  3 . It should be further noted that instead of two arms  68 , three, four or more said arms  68  may be used in order to improve the holding power of the assembly within conduit  3 . 
     The expander  60  is fabricated by high pressure injection molding. Expander  60  must be a relatively rigid part since when jacking nut receiver  66  is drawn into engagement with tubular portion  64 , the latter must not fail to stop the advancement of jacking nut receiver  66 . Such a failure could cause an overstressed condition on arms  68  and possible failure. Also, arms  68  must have elastic resiliency so that they can bow out as needed, and yet resume the non-bowed shape when jacking nut is drawn away from tubular portion  64 . Means they must not take a set even after long periods of time (weeks, months). This combination of physical rigidity and elastic resiliency is not common in engineering structural plastics. However, it is achieved using a mixture of approximately equal parts of polycarbonate plastic, and polyester plastic so that the finished part has a flexure modulus of between 220,00 and 320,000 psi, a tensile stress at its yield point of greater than 5,000 psi, a tensile elongation at break point of greater than 50%, and a notched Izod impact of greater than 8 ft-lb/in. This combination of physical characteristics has been found to be critical to successfully meeting the above stated objectives of this apparatus. 
     Embodiments of the subject apparatus and method have been described herein. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and understanding of this disclosure. Accordingly, other embodiments and approaches are within the scope of the following claims.

Summary:
A locking grating or seal for a conduit includes a cover positioned at one open end of the conduit and is removably engaged and axially aligned with, an expander positioned within the conduit. A jacking bolt penetrates the cover and the expander, and is threadedly engaged with a jacking nut in a position within the conduit and spaced apart from the expander. C-shaped elastically flexible arms are integrally engaged with the expander and with the jacking nut so that rotation of the jacking bolt enables the jacking nut to move toward the expander forcing the C-shaped arms to bow outwardly into contact with the conduit for gripping it.