Abstract:
A rail clamp for model railroad track has a base having an upper surface and a lower surface. The upper surface has two spaced apart hooks, each hook having its open end facing away from the open end of the other hook. Male fasteners extend through holes formed in the base component, spaced apart from the hooks a suitable distance to fit a train rail, and each male fastener engages a corresponding female fastener. One of the bottom flanges of a standard train rail fits under the hook, and the other flange is clamped down by heads of the male fasteners. Two conductive sheets lie on the base, each trapped under a rail and between a hook and a pair of screws.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to a model railroad track clamp for securing model railroad track rails, and in particular to a robust model railroad track clamp which ensures conductivity and/or isolation and rail alignment while also maintaining proper track gauge and physical appearance. 
       BACKGROUND 
       [0002]    Model railroad track typically comprises two (or more) metal rails, in lengths that are joined together end-to-end, and mounted on transverse ties. The rails imitate the rails of a full-sized railroad, and typically have a flat bottom formed by a pair of flanges projecting to both sides of the rail, which sits on the tie and is held down to the tie. In commercially manufactured track, the ties are usually of plastic or other insulating material. The ties both maintain the spacing or “gauge” between the rails and provide the appearance of ties similar to those used on a full-sized railroad. The two rails may be used to carry electrical voltages or currents that supply power and/or control signals to the trains, and/or that detect the presence of a train for signaling purposes. 
         [0003]    It is desirable for smooth running to ensure that the ends of adjacent lengths of rail are aligned accurately end-to-end, and that the gaps between the lengths are not too large. It is desirable to be able to connect adjacent lengths of rail electrically, but to have the option of isolating adjacent lengths of rail so as to divide the track into sections for power supply, signaling, and/or other control purposes. 
         [0004]    Model railroad rail clamps are commonly used for securing and aligning the rails of model railway track. An example of a previously proposed model railroad track clamp is shown in U.S. Design Pat. No. Des. 326,296 to Hillman. That clamp has two metal pieces, each with a groove to receive one of the bottom flanges of a standard railroad rail. The two pieces are tightened together by horizontal screws passing below the rails, with the ends of two adjacent lengths of rail gripped between the two pieces of the clamps. Another example of a previously proposed model railroad track clamp, commercially available from Split-Jaw Products, Inc., has a single piece on one side of the rails, and two separate pieces, each tightened to the single piece by a respective screw, on the other side of the rails. 
         [0005]    Often these rail clamps are made of extruded materials such as brass, aluminum or stainless steel, the process of extruding requires many steps to get to a finished product, and requires a large amount of material to obtain the required strength to secure and align the rails. Furthermore, the rail clamps occupy the space around and below the bottom flanges of the rails, and so require that a tie be removed or omitted in order to secure the rails. That can result in no parallel gauge being maintained at the rail joint, and a less than desirable appearance. Additionally, to achieve isolation of a rail one must also purchase separate rail clamps designed for this specific intended purpose. 
         [0006]    Therefore, it is desirable to have a rail clamp which is cost effective to produce, aligns the rail linearly and provides the option of either electrical conductivity or isolation. 
       SUMMARY 
       [0007]    An embodiment of a tie rail clamp assembly is described as having a base in which threaded bodies are secured into. The base bottom also contains geometric features used for securing the mating threaded fasteners. These threaded bodies along with hook like features secure the bottom of the four train rails. Additional pieces of conductive material are placed on top of the base in conjunction with each hook in order to facilitate electrical conductivity. An additional hole is provided for the attachment of electrical conductors. The additional piece of material also contains this hole. When the threaded bodies, the additional pieces of material, and the mating threaded fasteners are assembled to the base, a clamping mechanism is formed to secure rails, ensure conductivity, allow feeder connections, maintain gauge and create an esthetically pleasing look. 
         [0008]    A further embodiment of a rail clamp assembly for a model railroad track to form a structural connection between rails and that facilitates electrical conductivity, and rail alignment between rails of a model railroad track, comprises a base component having an upper surface and a lower surface, the upper surface having two spaced apart hooks formed thereon, each hook having its open end facing away from the open end of the other hook, two conductive sheets for disposing on the base component, each sheet extends from a hook to an edge of the base component so as to define a conductive layer for contact by a train rail, each conductive sheet attachable to the base component with mating male and female threaded fasteners, the male fasteners extending through holes formed in the base component and the conductive sheet at a location spaced apart from the hooks a sufficient distance to fit a train rail, each male fastener engaging a corresponding female fastener. 
         [0009]    In one variation, the additional pieces of conductive material are omitted or removed from the top of the base in order to facilitate electrical isolation at the connection of the rails. Pieces of electrically insulating material of the same size may then be substituted, in order to ensure that both the electrically conductive and the electrically isolating rail joints have the same height. 
         [0010]    In another variation, one of the additional pieces of conductive material is removed or omitted from the top of the base in order to facilitate electrical isolation, and the other additional piece of conductive material is present in order to facilitate electrical connection. 
         [0011]    The additional piece of material may be added on top of the base in order to facilitate an extra strength, even if not being used for electrical conductivity or isolation. 
         [0012]    The base member, and the additional piece of material, may be provided with an additional hole for an additional fastening member to secure the additional piece of material to the base member. 
         [0013]    In another variation, a clamp that is not also a tie has only one hook and retaining members for the ends of successive lengths of only one rail. 
         [0014]    In a further variation, a pair of clamps each have one hook, but the pair of clamps have connectors with which the clamps can be joined back to back to form a combined tie and clamp as described above. 
         [0015]    Where the joints between lengths of the two rails do not align exactly, the combined clamp and tie may be positioned so that it clamps a joint in one rail, and is secured to the other rail to form a tie. 
         [0016]    There is also provided a kit of parts containing at least the base member. The male threaded fasteners are preferably included. The female threaded fasteners are preferably also provided if those are not unitary with or already embedded in the base member. The additional piece of material, conducting or insulating, may also be included. 
         [0017]    An embodiment of a kit includes several base members, fasteners, and both conductive and insulating additional pieces of material. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]    For the purpose of illustrating the invention, there are shown in the drawings embodiments that are presently preferred, it being understood, however, that this invention is not limited to the precise arrangements and constructions particularly shown. 
           [0019]      FIG. 1 a    is a perspective view showing an embodiment of the rail clamp assembly, with rails, configured for conductivity. 
           [0020]      FIG. 1 b    is a perspective view showing an embodiment similar to  FIG. 1 a   , but without a tie. 
           [0021]      FIGS. 2 a  and 2 b    are exploded perspective views, corresponding to  FIGS. 1 a  and 1 b   , respectively, showing the rails in a disassembled state from the rail clamp assemblies. 
           [0022]      FIGS. 3 a  and 3 b    are exploded perspective views, corresponding to  FIGS. 1 a  and 1 b   , respectively, showing the rail clamps in a disassembled state. 
           [0023]      FIGS. 4 a  and 4 b    are bottom elevation views, corresponding to  FIGS. 1 a  and 1 b   , respectively, of rail clamp assemblies showing geometry used to hold and secure the female threaded fasteners. 
           [0024]      FIGS. 5 a  and 5 b    are perspective views, similar to  FIGS. 1 a  and 1 b   , respectively, showing an embodiment of the rail clamp assemblies with rails, without the additional conductive members. 
           [0025]      FIG. 6  is a perspective view of a further embodiment of a tie rail clamp assembly. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    An embodiment of a rail clamp assembly  6  is shown in  FIGS. 1 a , 2 a , 3 a , and 4 a   . The rail clamp assembly  6  includes a base  7 , two pieces of conductive material  8 , threaded male bodies  9 , preferably four, and threaded female bodies  10  (shown in  FIGS. 3 a  and 4 a   ). The base is preferably made from ultra-violet resisting plastic material, although other suitable materials may be used. 
         [0027]    As shown in the embodiment of  FIG. 1 a   , the base  7  includes a web  14  and has molded in hook-like features  15 , preferably on the inside of the rails  11  and which engage the lower legs or flanges of the rails to help maintain the proper gauging between rails. 
         [0028]    The conductive material  8  is preferably a material having good conductivity, such as copper. The conductive material  8  may be flat. Alternatively, as shown in  FIG. 3 a   , the conductive material may have a curled edge  23  that fits into the groove  22  under the hook-like feature  15 . The thickness of the conductive material is in this embodiment not critical. It should be sufficiently thick to remain rigid in normal use and provide sufficient conductivity, but to save material, no thicker than that. A hundredth of an inch (0.25 mm) is adequate. The threaded male bodies and threaded female bodies are preferably nuts and mating bolts or screws. In use the rails  11  would be installed on top of the additional pieces of conductive material  8 , with one flange  24  in the groove  22  of the hook  15  and the other flange  24  beneath the head of the threaded male bodies  9 . The threaded male bodies  9  are then tightened down, to apply pressure to the rails  11  securing the rails  11  firmly against the conductive material  8  and the base  7 . As shown in the drawings, in this embodiment countersink-headed screws are preferred, because the taper on the underside of the head of the screw then exerts a wedging action pressing the rail snugly into the groove under the hook  15 . 
         [0029]    The second embodiment of a rail clamp assembly  12  is shown in  FIGS. 1 b , 2 b , 3 b , and 4 b   . The rail clamp assembly includes a two piece base  13 , two pieces of conductive material  8 , four threaded male bodies  9 , and four threaded female bodies  10  (shown in  FIG. 3 b   ). In use the rails,  11 , would be installed on top of the additional pieces of conductive material  8  and beneath the head of the threaded male bodies  9 . Once secured, the taper on the underside of the head of the threaded male bodies  9  would apply pressure to the rails  11  securing the rails  11  firmly against the conductive material  8  and the base  7 . 
         [0030]    In the second embodiment of  FIG. 1 b    the base  13  does not include a connecting web  14  that acts as a tie between the two rails  11 . It can therefore be used to clamp the lengths of rail  11  where the spacing of the other ties (not shown) in the track results in a tie not being needed at the clamp position. The correct track gauge is then maintained by the plastic or other ties (not shown) that are supplied by the rail manufacturers. 
         [0031]    As best seen in  FIGS. 3 a  and 3 b   , an additional hole  16  is provided in rail clamp assemblies  17  and  18  respectively, which may be used for the connection of electrical feeder wires (not shown). These holes  16  pass through the conductive material  8  and the bases  7  and  13  respectively, and are provided with nuts similar to nuts  10 , see  FIGS. 4 a  and 4 b   . The holes  16  will therefore accept screws or bolts with the same thread as screws  9 . 
         [0032]    Additionally, the conductive material  8  preferably has a curled edge  23  that is the same shape as the inside of the hook feature  22 , as shown in  FIGS. 3 a  and 3 b   . The lower flange of the rail  24  shown in  FIGS. 2 a  and 2 b    rests inside of these curled edges  23  inside the hook features  22  and, once secured by the male threaded fasteners  9 , a secure conductive or isolated joint is formed. 
         [0033]      FIGS. 4 a  and 4 b    show the bottoms of bases  7  and  13 , with the geometric features or recesses  19  formed in each of the bases. The geometric features are shaped to mate with and retain the female threaded fasteners  10 ,  FIGS. 3 a  and 3 b   , in each iteration. It should be readily apparent that threads could be added to the bases which engage with the male threaded fastener, thus eliminating the need for the female fasteners and geometric shapes. 
         [0034]    An embodiment of a rail clamp assembly  20  is shown in  FIG. 5 a   . The rail clamp assembly includes a base  7 , four threaded male bodies  9 , and four threaded female bodies  10  (similar to that which is shown in  FIG. 3 a   ). In use the rails  11  would be installed on top of the base  7  and beneath the heads of the threaded male bodies  9 . Once secured, the taper on the underside of the head of the threaded male bodies  9  would apply pressure to the rails  11  securing the rails  11  firmly against the hook features  15  and base  7 . In this embodiment, the copper sheet or other conductive material  8  ( FIGS. 1 a  and 1 b   ) is omitted, and a layer of electrically insulating material (not shown) may be inserted between the abutting ends of each pair of lengths of rail  11 . The two lengths of rail are then securely connected mechanically, but assuming the clamp base member  7  or  13  is made of plastic material, there is no electrical continuity between the two lengths of rail  11 . This configuration is therefore useful for electrical isolation between two track sections. 
         [0035]    The second embodiment of a rail clamp assembly  21  is shown in  FIG. 5 b   . This is similar to  FIG. 1 b    but, like  FIG. 5 a   , omits the conductive material  8  of  FIGS. 1 a  and 1 b   . The rail clamp assembly includes a base  13 , four threaded male bodies  9 , and four threaded female bodies  10  (similar to that which is shown in  FIG. 3 b   ). In use the rails,  11 , would be installed on top base  13  and beneath the head of the threaded male bodies  9 . Once secured, the taper on the underside of the head of the threaded male bodies  9  would apply pressure to the rails  11  securing the rails  11  firmly against the hook features  15  and base  13  for electrical isolation. 
         [0036]    Alternatively, the electrically isolating configuration of  FIGS. 5 a  and 5 b    may be modified by inserting an electrically insulating sheet in place of the conductive material  8 , instead of simply omitting the conductive material  8 . That has the advantage of ensuring that the height of the rail clamp assemblies, from the bottom of the base  7  to the bottom of the rail  11 , is completely uniform. In the case of  FIGS. 1 a  and 5 a   , when using conductive material  8  with a curled edge  23 , it also has the advantage of ensuring that the track gauge is completely uniform. Whether these are sufficiently important factors to justify the extra cost and effort of supplying and using the insulating sheets depends on the thickness of the conductive material  8 , and how sensitive the particular railroad equipment used is to slight variations in line and gauge. 
         [0037]    Referring now also to  FIG. 6 , another embodiment is generally similar to those shown in  FIGS. 1 a  and 1 b   , and in the interests of conciseness the description of features that are the same is not repeated. However, in  FIG. 6  the base member is formed in two parts  13 , but one of the two parts  13  has the connecting web  14  that forms a tie between the two rails. The end of the connecting web and the facing side of the other base member part  13  have respectively a male connector  2  and a female connector  3  that allow the two halves to be coupled together to form a single tie clamp that can be used exactly as the tie clamp shown in  FIG. 1 a   . However, if separate clamps are desired, or only one clamp is desired, the assembly  4  without the connecting web (shown to the upper left in  FIG. 6 ) can be used on its own. 
         [0038]    While the invention has been disclosed with reference to certain preferred embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the invention, as defined in the appended claims and equivalents thereof. 
         [0039]    For example, in the interests of simplicity, it has been assumed in the foregoing description of the preferred embodiments that the two rails of the railroad track have joints level with each other, so that the described track clamp will clamp both joints. However, if the joints do not line up, one of the two halves of the separated clamp according to  FIG. 1 b    can be used for each joint, or a tie clamp according to  FIG. 1 a    can be used with one end clamping a joint, and the other end simply clamped onto the other rail opposite the joint. The latter arrangement would ensure an exceptionally secure and stable joint. 
         [0040]    Accordingly, it is intended that the invention not be limited to the described embodiments, but that it will have the full scope defined by the language of the following claims. Aspects thereof may also include combinations of the features recited in any two or more of the following claims.