Patent Publication Number: US-9889811-B2

Title: Forwardly and rearwardly folding roll-over protection structure

Description:
RELATED APPLICATION 
     The present application is a continuation of U.S. application Ser. No. 15/356,225 filed Nov. 18, 2016, entitled FORWARDLY AND REARWARDLY FOLDING ROLL-OVER PROTECTION STRUCTURE, which is a continuation of U.S. patent application Ser. No. 14/798,063 filed on Jul. 13, 2015, entitled FORWARDLY AND REARWARDLY FOLDING ROLL-OVER PROTECTION STRUCTURE, which claims the benefit of U.S. Provisional Application Ser. No. 62/023,617 filed on Jul. 11, 2014 entitled FORWARDLY AND REARWARDLY FOLDING ROLL-OVER PROTECTION STRUCTURE, and U.S. Provisional Application Ser. No. 62/065,542 filed on Oct. 17, 2014 entitled FORWARDLY AND REARWARDLY FOLDING ROLL-OVER PROTECTION STRUCTURE, each of which is hereby incorporated in its entirety by reference herein. 
    
    
     BACKGROUND 
     1. Field 
     The present invention relates generally to folding roll-over protective structures (so-called “ROPS”) of the type frequently used in connection with motorized riding vehicles such as lawnmowers, utility vehicles, and tractors. More specifically, embodiments of the present invention concern folding roll-over protective structures capable of releasable securement in rearward, upright, and forward configurations. 
     2. Discussion of Prior Art 
     A folding roll-over protection structure (hereinafter “ROPS”) is commonly fitted to an agricultural, construction, or turf-care vehicle to reduce the risk of operator injury in a roll-over event. Prior art ROPS designs typically have one rearward folded position intended for use during transport, storage or vehicle operation around low obstructions such as trees. The unfolded upright position is intended to provide roll-over protection for the vehicle operator. Such limited configurations can be problematic. Vibration of the ROPS in each of its operational configurations is also a problem. 
     SUMMARY 
     The following brief summary is provided to indicate the nature of the subject matter disclosed herein. While certain aspects of the present invention are described below, the summary is not intended to limit the scope of the present invention. 
     Embodiments of the present invention provide a folding ROPS that does not suffer from the problems and limitations of the prior art folding ROPS. 
     A first aspect of the present invention concerns a foldable ROPS for a vehicle moveable in a generally fore-and-aft direction. The foldable ROPS comprises a frame including a base section and an upper section. The base section is connectable to the vehicle. The upper section is swingable relative to the base section between a forward position in which the upper section projects forwardly from the base section, a rearward position in which the upper section projects rearwardly from the base section, and an upright position positioned between the forward and rearward positions. A hinge assembly connects the sections of the frame. The hinge assembly is configured to releasably secure the upper section in each of the positions. 
     Other aspects and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments and the accompanying drawing figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
       A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein: 
         FIG. 1  is a side elevation view of a motorized riding vehicle having a folding roll-over protection structure constructed in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is a rear isometric view of the roll-over protection structure as shown in  FIG. 1 , particularly illustrating the structure in the upright position in solid lines and in the forward and rearward position in broken lines; 
         FIG. 3  is a rear isometric view of the roll-over protection structure illustrated in  FIGS. 1 and 2 , showing the structure in the upright position; 
         FIG. 4  is a fragmentary, enlarged, rear isometric view of the left side of the roll-over protection structure shown in  FIG. 3 , particularly showing the hinge assembly; 
         FIG. 5  is a fragmentary, enlarged, rear isometric view of the right side of the roll-over protection structure shown in  FIG. 3 , particularly showing the hinge assembly; 
         FIG. 6  is a fragmentary, enlarged isometric view of the right side of the roll-over protection structure generally opposite that shown in  FIG. 5 ; 
         FIG. 7  is a fragmentary, exploded, enlarged isometric view of the left side of the roll-over protection structure generally opposite that shown in  FIG. 4 , particularly showing various components of the hinge assembly; 
         FIG. 8  is a fragmentary, exploded, rear isometric view of the left side of the roll-over protection structure similar to  FIG. 4 , but with the parts being removed to specifically show the position of the hinge plate; 
         FIG. 9  is a rear isometric view of the roll-over protection structure illustrated in the forward position; 
         FIG. 10  is a fragmentary, enlarged, rear isometric view of the left side of the roll-over protection structure shown in  FIG. 9 , particularly illustrating the hinge assembly; 
         FIG. 11  is a fragmentary, enlarged, rear isometric view of the right side of the roll-over protection structure shown in  FIG. 9 , particularly depicting the hinge assembly; 
         FIG. 12  is a fragmentary, exploded, rear isometric view of the left side of the roll-over protection structure similar to that shown in  FIG. 10 , but with parts being remove to specifically show the position of the hinge plate; 
         FIG. 13  is a rear isometric view of the roll-over protection structure illustrated in the rearward position; 
         FIG. 14  is a fragmentary, enlarged, rear isometric view of the left side of the roll-over protection structure shown in  FIG. 13 , particularly illustrating the hinge assembly; 
         FIG. 15  is a fragmentary, enlarged, rear isometric view of the right side of the roll-over protection structure shown in  FIG. 13 , particularly depicting the hinge assembly; and 
         FIG. 16  is a fragmentary, exploded, rear isometric view of the left side of the roll-over protection structure similar to  FIG. 14 , but with the parts being removed to specifically show the position of the hinge plate. 
     
    
    
     The drawing figures do not limit the present invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the preferred embodiments. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is susceptible of embodiment in many different forms. While the drawings illustrate, and the specification describes, certain preferred embodiments of the invention, it is to be understood that such disclosure is by way of example only. There is no intent to limit the principles of the present invention to the particular disclosed embodiments. 
     The drawings show a foldable ROPS  20  in accordance with one embodiment of the present invention installed on a motorized vehicle  22  that is schematically illustrated as a lawnmower (see specifically  FIG. 1 ). As is customary, the illustrated lawnmower  22  generally includes a frame  24 , front wheels  26 , rear wheels  28 , an engine  30 , a mower deck  32 , and a seat for the operator  34 . During operation of lawnmower  22 , the operator (not shown) sits in seat  34 . As will be described, ROPS  20  is connected to frame  24  adjacent seat  34  and extends vertically beyond seat  34  such that operator injury caused by a roll-over event and/or falling objects is reduced without significantly obstructing the operator&#39;s line of sight. 
     As will be apparent, the ROPS  20  is suitable for a wide variety of vehicle types having different constructions and is not limited to applications involving the depicted lawnmower  22 . As will be discussed below, various structural features of ROPS  20  depicted in the illustrated embodiment may be altered to accommodate different vehicle types and shapes without departing from the ambit of the present invention. 
     The ROPS  20  generally includes a frame  36  having a base section  38  and an upper section  40 , with the frame sections  38  and  40  being operably interconnected by a pair of hinge assemblies  42  and  44 . The frame  36  and hinge assemblies  42  and  44  are preferably constructed from ROPS grade materials, with such materials being defined herein as any material capable of conforming, or intended to conform, to the standards established by the Occupational Safety &amp; Health Administration. More particularly, the frame  36  and hinge assemblies  42  and  44  are preferably formed principally, if not entirely, of metal, such as stainless steel, low carbon steel, aluminum, etc. 
     In the illustrated embodiment, the frame  36  is constructed from tubular material, preferably steel, that has been formed into the desired shape. The preferred frame tubing has a substantially square transverse cross-section presenting four (4) integrally connected walls, including a front wall  46 , an outside wall  48 , a back wall  50 , and an inside wall  52 . It is to be understood however, that the principles of the present invention are equally applicable to ROPS frames having alternate cross-sectional shapes and constructions. 
     In the illustrated embodiment, the base section  38  is comprised of two spaced apart legs  54  and  56  that extend vertically from an attachment point (not shown) on the lawnmower frame  36 . The legs  54  and  56  are essentially mirror images of one another and like components will therefore be similarly numbered in the figures. Each of the legs  54  and  56  comprises a bottom portion  58 , a middle portion  60 , and a top portion  62 . 
     The bottom portion  58  includes a pair of spaced apart fastener receiving holes  64  and  66 , one or both of which are used to secure the bottom portion  58  to the lawnmower frame  36 . The illustrated bottom portion  58  comprises a straight vertical tube, with the holes  64  and  66  projecting therethrough in a fore-and-aft direction. 
     The middle portion  60  angles outwardly from the bottom portion  58  (the preferred angle being forty-five degrees). The preferred angular relationship of the middle portion  60  laterally offsets the top portion  62  relative to the bottom portion  58  such that the top of the frame  36  is wider than where it connects to the vehicle  22 . Furthermore, the middle portion includes a transverse through-slot  68 , for purposes which will be described. 
     The top portion  62  extends vertically from the middle portion  60 . The top portion  62  is formed with fastener holes  70  and pin-receiving holes  72  that pass through the outside and inside walls ( 48  and  52 ) thereof. The top portion  62  of legs  54  or  56  also include a pair of opposed slots  74  and  76  formed into the front and back walls ( 46  and  50 ) thereof (see  FIGS. 4-9 ). These features will be discussed in more detail below. The top portion  62  is also preferably shorter in length (or height) than the bottom portion  58 . 
     The leg portions  58 - 62  are preferably welded together to form the individual legs  54  and  56 , although other means for interconnecting the portions are within the ambit of the present invention. Base section  38  depicted in the illustrated embodiment is specifically configured to fit on the lawnmower depicted in  FIG. 1 . The depicted base section  38  can be altered to fit other vehicle types having various shapes and sizes without departing from the ambit of the present invention. For example, the base section of the present invention may be attached at various locations and by various attachment means without departing from the spirit of the present invention. Additionally, the base section of the present invention may have a substantially different shape and construction than that depicted in the illustrated embodiment and still be within the ambit of the present invention. Further, a base section comprising a single leg or more than two (2) legs is also within the ambit of the present invention. 
     In the illustrated embodiment, upper section  40  is constructed from a single piece of steel tubing having a generally U-shaped configuration. More particularly, the illustrated upper section  40  includes a pair of laterally spaced apart vertical arms  78  and  80  and a central horizontal bight  82  interconnecting the arms  78  and  80 . The arms  78  and  80  preferably align with the top portion  62  of legs  54  and  56 , respectively, of the base section  38 . It will be appreciated that the construction of the upper section  40  may be varied without departing from the spirit of the present invention. For example, it is within the ambit of the present invention for the arms to be disconnected rather than joined at their upper ends. The shape of each portion (i.e. arms and bight) of the upper section, as well as the overall shape of the upper section itself, may also be varied without departing from the spirit of the present invention. 
     As will be discussed in more detail below, projecting from the lower end of each arm  78  and  80  is slot  84  formed into the front wall  46  thereof to facilitate attachment of respective hinge assembly  42  or  44  (see  FIG. 12 ). 
     Because the base section  38  of the illustrated frame  36  includes a pair of discrete spaced apart legs  54  and  56 , the ROPS  20  includes the pair of hinge assemblies  42  and  44 , each associated with a respective one of the legs  54  and  56 . The principles of the present invention are equally applicable to an alternative ROPS having a single hinge assembly. For example, if the frame sections are joined at a single connection (e.g., where the base section includes only one leg), the alternative ROPS assembly may include only one hinge assembly. 
     In the illustrated embodiment, the hinge assemblies  42  and  44  are virtually mirror images of one another and for the sake of brevity, the description will focus on just one hinge assembly, with the components being similarly numbered. Each hinge assembly  42  or  44  is generally comprises a hinge plate  86 , a fastener assembly  88 , and a lock assembly  90 . The hinge plate  86  is preferably formed from a piece of metal plate stock. More preferably, hinge plate  86  is formed from a piece of plate steel having a thickness of about three-tenths (0.3) of an inch, although other suitable materials and thicknesses are within the ambit of the present invention. Perhaps best shown in  FIGS. 7 and 12 , the hinge plate  86  is preferably fixed to the respective upper arm  78  or  80  of the upper frame section  40 . Particularly, the plate  86  includes a slot  92  received on the back wall  50  of the corresponding arm  78  or  80 . The lowermost slot  84  in the arm  78  or  80  similarly receives the hinge plate  86 . This interlocking interconnection aligns the hinge plate  86  in the fore-and-aft direction and provides joining interfaces along which the hinge plate  86  and the corresponding arm  78  or  80  are attached. Preferably, a weld seam is provided along each such interface, such that the hinge plate  86  is fixed to the corresponding arm  78  or  80  for swinging movement therewith. 
     It should be further understood that the attachment of hinge plate to the sections may be reversed without departing from the spirit of the present invention. That is, principles of the present invention are equally applicable to the hinge plate being rigidly attached to the base section and swingably attached to the upper section. Additionally, the hinge plate may be rigidly attached to one of the sections by a means other than welding without departing from the spirit of the present invention. 
     The hinge plate  86  is uniquely configured to provide connection with the corresponding leg  54  or  56  of the base frame section  38 , support vibration dampeners (as will be described), and function as part of the lock assembly  90 . The slots  74  and  76  in the top portion  62  of the corresponding leg  54  or  56  receives the hinge plate  86  as it rotates to its various positions corresponding with the location of the upper frame section  40 . More particularly, a central pivot opening  94  generally aligns with the hole  70  in the top portion  62  of the corresponding leg  54  or  56 . An enlarged base  96  of the hinge plate  86  presents a pair of pin-receiving openings  98  and  100  and support-receiving opening  102  located generally therebetween. The plate  86  also presents an uppermost tang  104  that projects rearwardly from the back wall  50  of the corresponding arm  78  or  80 . A support-receiving opening  106  is defined in the tang  104 . An intermediate projection  108  also projects rearwardly relative to the corresponding arm  78  or  80  and presents a pin-receiving opening  110 . The purpose and function of each opening in the hinge plate  86  will be described further below. 
     Although the illustrated hinge plate  86  design is preferred, the principles of the present invention are applicable to alternative hinge plate configurations or to elimination of the hinge plate altogether. For example, each arm may alternatively be directly pivotally connected to the corresponding leg. 
     In the illustrated embodiment, fastener assembly  88  includes a pivot element preferably comprising the following components: a bolt  112 , a split bushing  114 , and a lock nut  116 . The bolt  112  passes through the aligned pivot opening  94  in the hinge plate  86  and the fastener holes  70  in the top portion  62  of corresponding leg  54  or  56  (see  FIGS. 7, 8, 12, and 15 ). The lock nut  116  secures the bolt  112  in place. The split bushing  114  is interposed between the bolt  112  and the oversized fastener holes  70  in the top portion  62 . Furthermore, the bushing  114  rotatably receives the shaft of the bolt  112  and thereby serves to permit swinging of the hinge plate  86  and corresponding arm  78  or  80  relative to the respective leg  54  or  56 . In this respect, the bolt  112  may be snugly received within the pivot opening  94  of the hinge plate  86 , although relative rotation between the bolt  112  and hinge plate  86  may be provided if desired. Furthermore, the bushing  114  preferably does not rotate relative to the corresponding leg  54  or  56 , although certain aspects of the present invention would encompass such relative rotation. It should be understood that various other means of swingably fastening the hinge plate to the base section are within the ambit of the present invention. For example, fastener assembly  88  may be alternatively constructed without departing from the spirit of the present invention. 
     In the illustrated embodiment, the lock assembly  90  includes the pin-receiving openings  98 ,  100 , and  110  in the hinge plate, the pin receiving hole  72  in the top portion  62  of the corresponding leg  54  or  56  of the base frame section  38 , and a lock member  118 . The lock member  118  preferably includes a pin  120  removably received in the pin-receiving hole  72  and one of the aligned pin-receiving openings of the hinge plate  86 , as will be described. The pin  120  preferably includes collar  122  and a compression spring  124  positioned between the collar  122  and the outside wall  48  of the top portion  62  of the corresponding leg  54  or  56 . The spring  124  yieldably urges the pin  120  out of pin-receiving hole  72  so as to facilitate unlocking of the lock assembly  90 . A retention clip  126 , preferably in the form of a cotter pin, is removably received on the end of the pin  120  opposite the collar  122 . The clip  126  serves to prevent unintended removal of the pin  120  and therefore unlocking of the lock assembly  90 . A tether  128  is preferably provided for preventing misplacement of the clip  126 . In the illustrated embodiment, one end of the tether  128  is secured to the pin  120  (adjacent the collar  122 ) and the opposite end is secured to the clip  126 . The tether  128  is preferably received in the through-slot  68  defined in the middle portion of the corresponding leg. 
     Again, the base  102  of the hinge plate  86  is disposed within the opposed slots  74  and  76  of the corresponding top portion  62 . As the upper frame section  40  is located in its respective operating positions, a corresponding pin-receiving opening in the hinge plate  86  aligns with the pin-receiving hole  72  in the corresponding top portion  62 . More particularly, with the illustrated ROPS  20 , the upper frame section  40  is positioned in three (3) discrete operating positions—the upright position ( FIGS. 3-8 ), the forward position ( FIGS. 9-12 ), and the rearward position ( FIGS. 13-16 ); although additional operating positions may be provided if desired. In the upright position of the upper frame section  40 , the pin-receiving opening  98  is aligned with the pin-receiving hole  72  (e.g., see  FIG. 8 ). In the forward position of the upper frame section  40 , the pin-receiving opening  100  is aligned with the pin-receiving hole  72  (e.g., see  FIG. 12 ). In the rearward position of the upper frame section  40 , the pin-receiving opening  110  is aligned with the pin-receiving hole  72  (e.g., see  FIG. 16 ). In each of the positions of the upper frame section  40 , the lock assembly  90  is placed in a locked condition to releasably secure the upper frame section  40  in that position by inserting the pin  120  into the aligned pin-receiving hole  72  and corresponding pin-receiving opening. The clip  126  serves to prevent inadvertent unlocking of the assembly  90 . When it is desired to shift the upper frame section  40  to a different position, the clip  126  is removed from the pin  120  and the pin  120  is pulled outwardly to at least disengage the hinge plate  86 . Such removal is facilitated by the spring  124 . The upper frame section  40 , and thereby the hinge plate  86 , swing until a different pin-receiving opening is aligned with the pin-receiving hole  72 . The pin is then reinserted to place the lock assembly  90  in the locked condition. It should be understood that the lock assembly of the present invention is not limited to lock assembly  90  depicted in the illustrated embodiment. 
     It is further noted that, when the upper section  40  is located in the upright position, base section  38  and upper section  40  are preferably inline, with an angle therebetween being about one hundred eighty degrees (180°) (see  FIGS. 1-8 ). When the upper section  40  is located in the forward position, the base section  38  and the upper section  40  preferably define an interior angle therebetween of about ninety degrees (90°) (see  FIGS. 9-12 ). When the upper section  40  is located in the rearward position, the base section  38  and the upper section  40  preferably define an interior angle therebetween of about fifty-two (52°) (see  FIGS. 13-16 ). It will be apparent, however, that the positions of the frame sections  38  and  40  in each of the operating positions may be varied to some degree without departing from the spirit of the present invention. For example, it is not required for the base section to be fixed in a vertical orientation. Furthermore, the portion of the upper frame section relative to the base section in each operational position may be varied by as much as twenty degrees (20°) in either direction. It is noted, however, that the illustrated forward position of the upper frame section  40  is particularly useful when shipping the vehicle  22  with ROPS  20  assembled thereto in a low-profile, enclosed crate. 
     The ROPS  20  preferably also includes resilient vibration dampeners  130  and  132  associated with each hinge assembly  42  and  44  to restrict relative vibrational movement of the frame and the hinge assembly. (The illustrated pairs of dampeners  130  and  132  associated with each hinge plate  86  are identical in configuration and the description will therefore refer to the pairs interchangeably.) In the illustrated embodiment, the dampeners  130  and  132  serve to dampen vibration when the upper frame section  40  is secured in each of the operating positions. The dampeners  130  and  132  are similarly constructed and therefore like components will be similarly numbered. In the illustrated embodiment, each dampener  130  or  132  includes a compressible cushion  134  supported on the hinge plate  86  by a nut-and-bolt assembly  136 . As will be described, each dampener  130  or  132  is configured to compressibly engage the corresponding leg  54  or  56  of the base section  38  when the upper frame section  40  is secured in one of the operating positions. More particularly, as perhaps best shown in  FIGS. 6 and 7 , when the upper frame section  40  is in one of the operating positions (such as the upright position shown in these figures), the space between the shaft of the nut-and-bolt assembly  136  and the front wall of the corresponding leg  54  or  56  is less than the radial dimension (measured radially from the inside diameter to the outside diameter) of the cushion  134 . This causes the cushion  134  to be resiliently deformed, and maintains a vibration reducing force on the components. Specifically, the compressed cushion  134  yieldably urges the upper frame section  40  rearwardly; however, such movement is prevented by the locking assembly  90 . These counteracting forces retain the ROPS  20  firmly in the upright configuration and eliminates vibration that might be caused by tolerances or slop, particularly at the connection points between components. Compressible cushion  134  is constructed from a compressible material, such as polyurethane or another material having comparable elasticity. 
     In the illustrated embodiment, the dampener  132  is attached to the tang  104  of the hinge plate  86  by passing the shaft of the nut-and-bolt assembly  136  through the support-receiving opening  106 . The dampener  130  is removably supported on the hinge plate  86  at the support-receiving opening  102 , for purposes which will be described. 
     It will be appreciated, however, for the resilient vibration dampeners to be alternatively constructed without departing from the ambit of the present invention. For example, the cushion support need not comprise a nut-and-bolt assembly, but rather a simple peg or stub shaft (both not shown) attached to the hinge plate may alternatively be used. Furthermore, the dampeners need not be supported on the hinge plate. For example, the dampener may be directly coupled between each arm and corresponding leg. Yet further, the dampeners need not be resiliently compressed. Instead, it is entirely within the ambit of the present invention for one or more or all of the dampeners to be resiliently stretched. For example, elastic bands may alternatively be operably coupled between the frame sections to reduce vibration. The number and location of the dampeners may also be altered without departing from the spirt of the present invention. 
     Again, when the upper frame section  40  is in the upright position (see  FIGS. 3-8 ), the dampener  130  on the base  96  of the hinge plate  86  serves to reduce vibration of the ROPS  20 . More particularly, the cushion  134  of the dampener  130  compressibly engages the front wall  46  of the top portion  62  of the corresponding leg  54  or  56 . When it is desired to swing the upper frame section  40  to the forward position (shown in  FIGS. 9-12 ), in addition to unlocking the lock assembly  90 , the illustrated embodiment requires the dampener  130  to be removed. This is accomplished simply by disassembling the nut-and-bolt assembly  136  of the dampener  130  and removing the dampener  130 . Once the support-receiving opening  102  in the hinge plate  86  is positioned on the opposite (i.e., rear) side of the corresponding leg  54  or  56 , the dampener  130  is reattached to the hinge plate  86 . The upper frame section  40  is then forced into the forward position, causing the cushion  134  of the dampener  130  to compress against the back wall  50  of the top portion  62 , and the locking assembly  90  is then positioned in the locked condition. Because of the added steps required to swing the upper frame section  40  to the forward position, the operator is essentially prevented from doing so during operation of the vehicle  22 , which provides added safety to the ROPS. On the other hand, if it desired to move the upper frame section  40  from the upright position to the rearward position (see  FIGS. 13-16 ), the locking assembly  90  is unlocked and the dampener  130  is forced into compressive engagement with the back wall  50  of the top portion  62 . Of course, repositioning of the upper frame section  40  from the rearward position to the forward position, or vice versa, will require removal and re-attachment of the dampener  130 . 
     The lock assembly  90  may be fitted with additional means of vibration reduction. In the illustrated embodiment, locking pin  120  is fitted with spring  124  to reduce movement of the locking pin  120  when positioned in the locked condition. Various coatings known to those having skill in the art may also be applied to areas prone to vibration. 
     The ROPS is preferably in the upright position during operation of the vehicle. When the ROPS is in the upright configuration, the upper section extends vertically to a point beyond the height of an operator seated in the vehicle. If a roll-over event occurs when the ROPS is in the upright configuration, the ROPS provides protection to the operator. Additionally, when the ROPS is in the upright configuration, the ROPS reduces the risk of operator injury from falling and overhanging objects. The folding action of the ROPS to a forward or rearward position allows the vehicle fitted with the ROPS to be stored in a wider variety of locations of limited space. 
     The preferred forms of the invention described above are to be used as illustration only and should not be utilized in a limiting sense in interpreting the scope of the present invention. Obvious modifications to the exemplary embodiments, as hereinabove set forth, could be readily made by those skilled in the art without departing from the spirit of the present invention. 
     The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and access the reasonably fair scope of the present invention as pertains to any apparatus not materially departing from but outside the literal scope of the invention set forth in the following claims.