Abstract:
A tool or device is comprised of a generally cylindrical plunger that is retained in a generally cylindrical body. A spring fits inside the body to spring-load the plunger by means of a jam nut or other tensioning device. The plunger has tapped mounting holes with a pilot hole on the compression end for attaching various standard or custom components or attachments. The opposite tension end has a threaded extension also used for attaching devices. The body has a smooth outside diameter with at least one flat running the entire length. Due to the close fit of the plunger and body, the plunger has an axial groove on it upper surface to allow air inside the device to escape for smooth actuation. An optional splitclamp block is provided as a means of mounting. Also available as an option is a retracting lock.

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     The present invention relates to machine components in general and in particular to a universal spring biased device having a plunger, which may receive a first and second attachment. 
     2. Discussion of the Related Art 
     Spring loaded machine components and tools are well known in the art. For example, various spring loaded fixturing components can be used as clamping mechanisms for various tool and machine applications. These conventional spring-loaded devices are individually designed for many different applications. This forces manufacturers, distributors or users to keep a large assortment on hand. Often a custom device must be designed and built because a standard device is not available with the correct features. Applications include, but are not limited to, holding, locating, stopping, braking, cushioning, indexing, latching, push or pull pins, and remote control applications. 
     Conventional spring loaded devices also generally have a hollow center for receiving a plunger. Typically, such conventional spring loaded devices have a single fixed attachment for a specialty function such as being received in a detent. However, what is needed is a spring-loaded device, which is useful for a wide universe of applications. What is also needed is a device that is easily adapted for many applications using standard or custom add-on components and attachments. 
     SUMMARY OF THE INVENTION 
     The spring-biased device of the present invention is comprised of a steel cylindrical body having an orifice. A hardened steel cylindrical plunger is received in the orifice and held in place by means of a jam nut or other device. The spring surrounds the plunger and is operably contained between the plunger and the body. The plunger has a first end or compression end and a second end or tension end. The first end has a hole therein for receiving a first attachment. The second end has threads for receiving a second attachment. A retracting lock maybe attached to the second end to engage the body and ensure that the plunger&#39;s movement is limited. The body is constructed of round stock and may have at least one flattened side. Preferably, the body has two flattened sides so that the body can be held steady with a conventional wrench during attachment and detachment or prevent interference with burrs caused by set screw mounting. Further, the flats engages tangs of the retractable lock to prevent movement. 
     A clamp is preferably associated with the body for attachment of the device to a mounting or support member. In one preferred embodiment a split clamp having an upper clamp portion and a lower clamp portion is used to form a mounting block for attachment of the body to the mounting member. At least one screw secures the clamp portions to each other and thereby restricts the movement of the body. 
     The plunger preferably has an axial groove. There may also be a groove in the body for receiving a key. A key may also fit into the axial groove to restrict the movement of the plunger. The plunger may also have preferably two flattened sides so that it can be held steady by a wrench during tightening. The hole at the plunger first end preferably has tapped threads to engage threads on the first attachment. The plunger second end preferably has an extension with threads along its length to engage the threads contained in the hole in the second attachment. The threaded hole of the second attachment and the threaded extension of the first attachment can receive a variety of attachments such as knobs, bolts, stopping members, gripping contact bolts, wheels, etc. Therefore, the tool may be used in both tension and compression applications. 
     The inventive tool may further be a precision spring-loaded cylinder of universal design for use in custom automation and fixturing applications. For example, unlike current spring stops and plungers, this tool may have tapped holes with a pilot hole on the end of the plunger for easy attachment of standard or custom details. A range of sizes is available to obtain the optimum spring force, and stroke and plunger diameter combinations for a multitude of applications. An optional retracting lock and a split-clamp-mounting block can also be provided. The device may be welded, bonded, or press fit into place on the mounting member. 
     Because the preferred body is made from round stock instead of the threaded body found on many conventional devices, the inaccuracies inherent with thread runout are avoided. The universal spring devices are made to close tolerances in order to handle accurate indexing applications as well as many other applications. Hardened steel plungers extend completely through the body, providing a large bearing surface for side and offset loading. Moreover, when used in typical spring stop applications, the body can be easily adjusted axially whereas conventional spring stops cannot. 
     In one preferred embodiment, the split clamp mounting block has at least one clearance hole for mounting the block to the mounting member. The preferred embodiment of the clamping block has holes for receiving screws, which may be tightened by a wrench. In another preferred embodiment, the clamp may have a hole for receiving at least one set screw to hold the clamp in place relative to the body. 
     At least one of the tension and/or compression end may be chamfered so that the end can be received in a receiving cavity. In another preferred embodiment, a pilot hole is used for centering the attachments and helping to locate the attachment into the hole in the end of the plunger. 
     The plunger lock can preferably be retracted and rotated 90° to lock the plunger in a retracted position. The retracting lock preferably attaches to the threaded extension at the tension end. The axial groove along the outer surface of the plunger allows air to escape from inside the body&#39;s orifice and thus allows for smooth, rapid plunger actuation. 
     Dowel pin holes allow the clamps to be mounted to pins contained in the mounting member. The inventive device may be a long stroke device or a short stroke device. Also, a light spring or a heavy spring may be used depending on the application. The spring may have a spring force between 0.5 and 71.25 foot pounds. Additionally, a snap ring, cable or jam nut may be included for tensioning the spring. The body is preferably machined from cold rolled steel. The steel body device preferably has black oxide finish and the plunger is preferably made of case hardened steel with a black oxide finish. However, any steel or aluminum may be used. In other preferred embodiments stainless steel or other forms of carbon steel may be used to improve wear resistance, corrosion resistance, and heat resistance. In some applications nylon, delrin or other forms of plastic maybe used so as not to mar soft materials such as aluminum or brass. In other applications, the device may be made of a phenolic or other fiber/resin material. Close tolerances may also be desirable. 
     One of the advantages of using the spring-loaded device of the present invention is that it allows for accurate and repeatable end forces. Further, it allows for side loading, its easier to install then conventional standard springs, the projection is repeatable time after time, the spring has a minimal compression set, the spring loaded component can be used in a variety of products, machine tools, fixtures, and assembly tools, and it can vary in size and weight as illustrated by the table below. 
     In yet another preferred embodiment, a sensor is attached to at least one of the compression end or the tension end. The sensor senses the plunger&#39;s movement. 
     In another embodiment, a remote actuating cable is attached to the tension end. The actuating cable moves the plunger relative to the body. 
     In still another embodiment, the invention may be used in a fixturing device in conjunction with a moving member. 
     Other applications include bumpers, stopping, indexing, latching, pull or push pinning, locating, holding, braking and other applications including remote applications. 
     These and other aspects of the present invention will be better appreciated and understood when considered in conjunction with the following description in the accompanying drawings. It should be understood however, that the following description, while indicating preferred embodiments of the present invention, is given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the present invention without departing from the spirit thereof, and the invention includes all modifications. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The clear conception of the advantages and features constituting the present invention, and of the construction and operation of typical mechanisms provided with the present invention, will become more readily apparent by referring to the exemplary and therefore non-limiting, embodiments illustrated in the drawings accompanying and forming a part of this specification and wherein like reference numerals designate the same or like elements in several views and in which: 
     FIG. 1 is a top view of one embodiment of the present invention; 
     FIG. 2 cross sectional view the invention of FIG.  1 . 
     FIG. 3 is an exploded view of one embodiment of the present invention. 
     FIG. 4 is the front view of invention of FIG.  1 . 
     FIG. 5 a  is a front view of another embodiment of the present invention; 
     FIG. 5 b  is a side view of the invention of FIG. 5 a;    
     FIG. 6 a  is a front view of the invention shown in FIG. 3; 
     FIG. 6 b  is a side view of the invention of FIG. 3; 
     FIG. 7 a  is another front view of another embodiment of the present invention; 
     FIG. 7 b  is a side view of the invention shown in FIG. 7 a;    
     FIG. 8 is a side view of another embodiment of the present invention; 
     FIG. 9 is a side view of another embodiment of the present invention; 
     FIG. 10 is a top view of yet another embodiment of the present invention; 
     FIG. 11 is a top view of still another embodiment of the present invention; 
     FIG. 12 is a side view of yet another embodiment of the present invention; 
     FIG. 13 is a side view of still another embodiment of the present invention; 
     FIGS. 14 a-c  are side views of still another embodiment of the present invention; 
     FIG. 15 is a top view of yet another embodiment of the present invention; 
     FIG. 16 is a side view of still another embodiment of the present invention; 
     FIG. 17 is a side view of still another embodiment of the present invention; 
     FIG. 18 is a side view of still another embodiment of the present invention; 
     FIG. 19 is a side view of another embodiment of the present invention; 
     FIG. 20 is a side view of still another embodiment of the present invention; 
     FIG. 21 is a top view of another embodiment of the present invention; 
     FIG. 22 is a side view of another embodiment of the present invention; 
     FIG. 23 is a side view of still another embodiment of the present invention; 
     FIG. 24 is a front view of still another embodiment of the present invention. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     The present invention and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments described in detail in the following description. Referring more particularly to FIGS. 1-24, wherein like numbers refer to similar parts, the universal spring tool or device  5  for a machine of the present invention is comprised of a body  6  including the first body end  6   a  and the second body end  6   b . As best seen in FIG. 3, an orifice  7  is contained in the body and preferably passes completely there through lengthwise. 
     Referring now to FIG. 1, the body  6  is preferably constructed of non-threaded, round, rolled steel stock. A plunger  8  is preferably operably associated with the body  6  and is received in the orifice  7  (FIG.  2 ). Plunger  8  includes a first plunger end or compression end  11  and a second plunger end or tension end  10 . Compression end  11  preferably has a hole  15  therein. The second plunger end or tension end  10  preferably has a threaded extension  9 . In one preferred embodiment as shown in FIG. 2 the first end  11  has a pilot hole  14  to ensure proper centering and location of a first attachment which is received by the hole  15 . In one preferred embodiment the hole  15  has threads for receiving the first attachment  25  as best shown in FIG.  2 . As shown in FIG. 2, the pilot hole  14  is slightly larger than the hole  15 . 
     A biasing means or spring  12  is operably associated with the plunger and fits into the orifice  7  in the body  6 . Spring  12  provides tension and compression to the plunger as best shown in FIG.  2 . Referring again to FIG. 1, one preferred embodiment has a nut  13  with a threaded hole which acts to jam the end  10  against the body for creating a tension on spring  12  and thus restricts movement of the plunger  8 . 
     Referring to FIG. 1, the body  6  preferably includes at least one flat side  17  for allowing the body to be held in place during tightening. In one preferred embodiment, the body  6  has two flat sides  17   a  and  17   b  so that a wrench can hold the body in place. Similarly, the plunger  8  has at least one flattened side  23  to accommodate a wrench during tightening. Axial groove  22  may also be part of the plunger  8 . The axial groove  22  is used primarily to allow air to escape the orifice  7  when the plunger  8  is forced into the body  6 . 
     FIG. 3 shows another embodiment of the present invention. In this exploded view the plunger  8  is shown exploded out of the orifice  7  of the body  6 . The spring  12  is shown surrounding the plunger  8  and inserted into the orifice  7  of the body  6 . Also shown is a clamp  18 , preferably a split clamp mounting block, having an upper or first portion  18   a  and a second or lower portion  18   b . Clamp contains holes  20   a  and  20   b  for receiving screws  24 . The screws  24  hold the first portion of  18   a  and the second portion  18   b  of the clamp together tightly around the body  6  of the device  5 . 
     FIG. 3 also shows retracting lock  21  which is also, generally cylindrical in shape and mounted between the first body end  6   a  and the jam nut  13  along the extension  9  of the plunger  8 . Preferably, a pair of tang  21   a  and  21   b  project from lock  21 . 
     FIG. 4 more clearly illustrates the flat sides  17   a  and  17   b  of the body  6  and the flat portions  23   a  and  23   b  of the plunger  8 . In this embodiment, a key  22   a  is placed in the groove  22  of plunger  8  and groove  22   b  of the body  6  to prevent the plunger from moving radially. 
     FIGS. 5 a  and  5   b  show another embodiment of the device  5  of the present invention. Here the clamp  18  having first portion  18   a  and second portion  18   b  is held together with two screws  24   a  and  24   b  as shown. The clamp  18  squeezes the body  6  tightly as the screws  24   a ,  24   b  are tightened. The second portion  18   b  of the clamp  18  has dowel pin holes  19   a  and  19   b  to allow the clamp to be attached to a larger device such a machine. 
     FIGS. 6 a  and  6   b  show the embodiment of FIG. 3 from both the front view (FIG. 6 a ) and a side view (FIG. 6 b ). As illustrated, tangs  21   a  and  21   b  projecting from the retracting lock  21  engage the flats  17  to limit movement of the plunger  8 , for example, preventing the plunger  8  from rotating more than a few degrees in this embodiment. Extension of the plunger  8  may also be limited. FIGS. 7 a  and  7   b  show yet another embodiment of the machine component  5  with the lock  21  disengaged from the body  6 . In this embodiment, the retracting lock  21  may be attached to the plunger  8 . The tangs  21   a  and  21   b  are specially machined and dimensioned to engage the flats  17  of body  6 . A snap ring  46  may engage the threaded extension  9  of the tension end  10 . 
     FIG. 8 shows another embodiment of the device  5  of the present invention. In this embodiment, the body  6  and the plunger  8  are secured to a supporting member  54 . The clamp force is provided by a standard shaft collar  50 , which is tightened by a bolt  52 . Weld  44  connects the collar  50  to the member  54 . 
     FIG. 9 shows an embodiment of the device  5  of the present invention wherein a body  6  is secured to a supporting member  54  by welds  44   a  and  44   b.    
     FIG. 10 shows device  5  of the present invention wherein the device is used for a roller detent application on a cam or wheel  60 . Attached to the compression end  11  of the plunger  8  is a first attachment  25 . The first attachment has a roller  38  attached to its outer most end. The device  5  is attached to a mounting or supporting member  54  by clamp  18  and dowel pins  19   a  and  19   b . Body  6  is contained by the clamp portions  18   a  and  18   b . At the tension end  10  is a retracting lock  21  which is secured by a jam nut  13  which engages the threaded extension  9  of the plunger  8 . In this roller detent application the roller  38  allows the wheel  60  to advance in a controlled fashion as the device  5  asserts pressure on the roller  60 . The retracting lock  21  used in this application acts as an anti-rotation device for the plunger  8  and first attachment  25 . 
     FIG. 11 shows the device  5  being used in a indexing application with the wheel  60 . Tension end  10  of the plunger  8  has a jam nut  13  and a second attachment  27 . In one preferred embodiment, the attachment  27  is a knob  34  as shown. On the compression end  11 , the chamfered edges  32  of the plunger  8  engage receiving cavity  62  located in the wheel  60  as the wheel  60  advances. Device  5  is attached to a mounting member  54  by a clamp  18 . The clamp  18  may be secured to the mounting member  54  by screws  24   a  and  24   b . Also shown is flat  17  which allows for the body  6  to be held in place during tightening by a wrench. 
     FIG. 12 shows the device  5  being used in a tension/rotation application. In this application, device  5  is attached to a clamping member  64  which has a hole for receiving the plunger  8 . A clamping arm  53  applies tension forces to a workpiece  68 , which comes into communication with locating stop  55 . Stop  55  is mounted to support member  54 . Threaded extension  9  of the plunger is attached to a second attachment  27 . In this embodiment, the second attachment  27  is preferably a knob  34 . Setscrew  30  holds device  5  inplace. 
     FIG. 13 shows the device  5  of the present invention being used in a pull and turn retracting lock application. In this embodiment, a first attachment  25 , in this case a locating pin  35 , engages a receiving cavity  62  as shown. The body  6  is again held in a clamp  18  having a first portion  18   a  and a second portion  18   b . The first portion  18   a  and the second portion  18   b  of the clamp  18  are held together by screws  24   a ,  24   b  which secure the clamp to a machine mounting member  54 . At tension end  10 , retracting lock  21  and turning it 90° prevents locating pin  35  from engaging the cavity  62 . Attached to the threaded extension is a second attachment  27 . In this embodiment, the second attachment  27  is a knob having a rounded head  34 . FIGS. 14 a - 14   b  show various machine components  5  of the present invention having first attachments  25  of various shapes and sizes. These attachments  25  can be customized depending on the type of application. Each of the attachments  25  are engaged in a hole  15  at the compression end  11  of the plunger  8  as shown in each of the FIGS. 14 a ,  14   b  and  14   c.    
     FIG. 15 shows the device  5  of the present invention wherein multiple devices  5  are used as stops in an application. The compression end  11  of the plunger  8  is shown engaging a target member or workpiece  68 . The chamfered end  32  provides for less friction during the engagement. Opposite the compression end  11  is the tension end  10 , which has attached to it a second attachment  27 . A retracting lock  21  allows retracting the plunger  8  to select 3 different stop positions as required. The devices  5  are held in place by a single clamp  18 , which is secured by screws  24 . 
     FIG. 16 shows a standard gripper contact bolt application. In this application the tension end  10  has a remote actuator  64  attached to it. The actuator  64  is generally concealed by an enclosure  65 . Opposite the tension end  10  is the compression end  11  which has a gripper contact bolt  66  engaged in hole  15  as shown. The gripper contact bolt  66  has slightly raised tine members to engage the target member  68  and prevent it from slipping. 
     FIG. 17 shows the device  5  of the present invention in use in a spring stop application. In this embodiment, a flat locating face  70  is attached to the compression end  11  of the plunger  8 . The locating face  70  engages the target member  68  as shown. The body is held in place by a clamp  18 , which is secured, to mounting member  54  by screws  24 . Jam nut  13  threadingly engages the threads of the tension end  10  of the plunger  8 . 
     FIG. 18 shows a remotely actuated cable application of the device  5  of the present invention. In this embodiment a cable  42  is attached to second attachment  27 . Second attachment  27  is threadingly engaged to the threads  9  from the tension end  10  of the plunger  8 . The compression end  11  is received in a receiving cavity  62  of the target member  68 . Body  6  is held in place by a first portion  18   a  and a second portion  18   b  of a clamp  18 . At least one screw  24  is received in the first portion  18   a  and in the second portion  18   b  to engage mounting member  54 . 
     FIG. 19 shows the device  5  of the present invention being used in a standard swivel pad application. In this embodiment the tension end  10  is engaged by a second attachment  27 . Second attachment  27  is a knob  34  with a rounded head. Opposite the tension end  10  is the compression end  11  which has a first attachment  25  attached thereto. The attachment  25  has a swivel pad  80  at its outer most end. The swivel pad  80  engages workpiece or target member  68 . In this embodiment the body  6  of the device  5  is attached to mounting member  54  by clamp  18  having a first portion  18   a , a second portion  18   b  and a screw  24  received therethrough. 
     FIG. 20 shows another application of the device  5  of the present invention. In this embodiment compression end  11  receives an L-shaped or other irregular-shaped first attachment  25 . The attachment  25  is held in place by a flathead screw  47 . The L-shaped first attachment  25  engages target member  68 . In this embodiment body  6  of the device  5  is held in place with a clamp  18  secured to a mounting member  54  by a screw  24 . A set screw  30  provides a compression force to the body  6  to prevent the body from moving within the clamp  18 . A jam nut  13  is threadingly engaged to threads  9  of the plunger  8  at the tension end  10 . 
     FIG. 21 shows multiple devices  5  being used in a spring loaded guide rail application. In this embodiment a body  6  is secured by a clamp  18  as shown. Attached at compression end  11  by a screw  30  is a spring loaded guide rail  73 . The spring loaded guide rail  73  applies force to workpieces  72 , which are contained in track  71 . As the spring loaded guide rail  71  applies force to the workpieces  72 , they in turn are pushed up against stationary guide rail  74 . 
     FIG. 22 shows the device  5  of the present invention being used in a tension application. The device  5  in this embodiment is mounted under the mounting member  54 . In this embodiment second attachment  27  is attached to tension end  10 . Attachment  27  frictionally engages target member  68  as shown. A clamp  18  having a first portion  18   a  and a second portion  18   b  secures the body to mounting member  54  a screw  24  is received by an anti-rotate plate  84  which in turn is attached to the clamp  18  by the screw  24 . 
     In FIG. 23, device  5  of the present invention is shown being used in a stop block sensor application. First attachment  25  is engaged to the plunger  8  at compression end  11  as shown. At the other end, a jam nut  13  is attached to threaded extension  9  of the tension end  10 . A body  6  of the device  5  is secure to the mounting member  54  by a clamp  18 . A screw  24  is received in holes in the clamp  18  and the mounting member  54 . Also attached by the screw is a bracket  41 , which is attached to clamp  18 . The bracket  41  supports a sensor  40  to determine the movement of the plunger  8  and sense the position of the workpiece  68 . 
     FIG. 24 shows two devices  5  of the present invention in an offset loading/clamping application. The devices  5  are held in place by a clamp  18 , which is connected, to a mounting member  54  by screws  24   a  and  24   b . The devices  5  are secured because setscrews  30  engage the flats  17 . Attached to the compression ends  11  of the devices  5  is a triangular plate  75  upon which is mounted a contact bolt  76 . 
     The inventive tool  5  may come in various sizes. For example, there may be at least 4 short-stroke sizes and 4 long-strokes sizes as best-illustrated in Table 1 below. The long-stroke spring tools are preferably made with light or heavy springs. The short-stroke spring tools may closely approximate conventional spring stops in size and spring rate. In addition, there may also be at least one larger short-stroke tool. 
     
       
         
               
               
             
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 PLUNGER DIA. 
               
             
          
           
               
                   
                 {fraction (5/16)}″ 
                 ½″ 
                 ⅝″ 
                 1″ 
               
             
          
           
               
                   
                 STROKE 
               
             
          
           
               
                 SPRING 
                 ⅛″ 
                 ⅜″ 
                 {fraction (3/16)}″ 
                 {fraction (9/16)}″ 
                 ¼″ 
                 ¾″ 
                 ⅜″ 
                 1⅛″ 
               
             
          
           
               
                 FORCE 
                   
                 LT. 
                 HVY. 
                   
                 LT. 
                 HVY. 
                   
                 LT. 
                 HVY. 
                   
                 LT. 
                 HVY. 
               
               
                   
               
             
          
           
               
                 END 
                 INITIAL 
                 4.75 
                 0.5 
                 1.5 
                 8.5 
                 2 
                 5.5 
                 14 
                 2 
                 6 
                 35.5 
                 2.5 
                 6.5 
               
               
                 FORCE 
                 HALFWAY 
                 9.75 
                 1.5 
                 4 
                 21.75 
                 3.5 
                 10 
                 28 
                 5.5 
                 15 
                 53.5 
                 8 
                 21 
               
               
                 (LBS.) 
                 FINAL 
                 14.5 
                 2.25 
                 6.5 
                 34.75 
                 5 
                 14 
                 42 
                 8.75 
                 24 
                 71.25 
                 13.75 
                 35.75 
               
               
                   
               
             
          
         
       
     
     The spring-biased device  5  is preferably constructed of steel, although various components may be made from a multitude of materials including aluminum, stainless steel, plastics, etc. A black oxide finish preferably is applied to improve corrosion resistant. However, other treatments to add corrosion resistance are contemplated. 
     There are virtually enumerable uses for the present invention, all of which need not be detailed here. For example, the machine tool  5  may be used on any machine application including: assembly lines, production machinery, material handling, deburring machines, grinding machines, welding machines, fixturing applications, bottling and canning operations, CNC machines, drill presses, etc. Moreover, all of the disclosed embodiments can be practiced without undue experimentation. 
     Although the best mode contemplated by the inventors of carrying out the present invention is disclosed above, practice of the present invention is not limited thereto. It will be manifest at various additions, modifications, and rearrangements of the features of the present invention may be made without deviating from the spirit and scope of the underlying inventive concept. Moreover, the individual components need not be formed from the disclosed materials, in a disclosed shapes, or assembled in a disclosed configuration, but could be fabricated from virtually any suitable materials, could be provided in virtually any shape, and assembled in virtually any configuration. 
     Further, although various steps and components are described herein as physically separate modules, it will be manifest that they can be integrated into the steps or apparatus with which they are associated. Furthermore, all of the disclosed features of each disclosed embodiment can be combined with, or substituted for, the disclosed features of every other disclosed embodiment except where such features are mutually exclusive. The terms upper, lower, top, bottom and the like in the specification in claims are intended to assist the reader in understanding the invention and are not intended as terms of limitation. 
     It is understood that the invention is not limited to the particular embodiments disclosed and illustrated herein but embraces such modified forms thereof as come within the scope of the following claims. It is intended that the appended claims cover all such additions, modifications, and rearrangements. Expedient embodiments of the present invention are differentiated by the appendent subclaims.