Abstract:
A liquid-holding tank for mounting on the frame of a vehicle is disclosed. The tank comprises an elongate tank body and a tank frame coupled to the elongate tank body and extending downwardly therefrom. The tank frame and the elongate tank body form a reservoir, and the tank frame is adapted to rest directly on the vehicle frame.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/033,559 filed Mar. 4, 2008 the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    Vehicle mounted tanks that carry liquids face design challenges not applicable to stationary tanks. The design challenges relate primarily to the mass and nature of liquid when put into motion. The vehicle carrying the tank may be hard to handle and may be prone to roll-overs due to the momentum of the liquid. 
       SUMMARY 
       [0003]    In one exemplary embodiment, a liquid-holding tank for mounting on the frame of a vehicle is disclosed. The tank comprises an elongate tank body having curved side walls coupled to and disposed above a generally rectangular frame. The elongate tank body defines an interior chamber. The frame has generally vertical side walls extending from a generally planar tank floor. The generally vertical side walls are coupled to the curved side walls. The frame is adapted to directly support the tank on the vehicle frame, and the frame is further adapted to be in fluid communication with the chamber and receive the liquid, thereby lowering a vertical center of gravity of the tank. Front and rear vessel heads are coupled to the curved side walls and frame, and a lid is coupled to the curved side walls and the vessel heads. At least one longitudinal baffle is coupled longitudinally inside the chamber, and at least one transverse baffle is coupled transversely inside the chamber. 
         [0004]    In another exemplary embodiment, a liquid-holding tank is disclosed comprising an elongate tank body having curved side walls coupled to front and rear heads. The tank body generally defines an upper liquid containment area and a closed-bottom tank frame is coupled to the curved side walls. The tank frame is further coupled to and extends between the front and rear heads. The tank frame extends downwards, and generally defines a lower liquid containment area which is fully open to the upper containment area. The upper and lower containment areas form a total containment area. The lower containment area is operable to lower a vertical center of gravity of the total containment area. The tank frame comprises an integral structural support and the tank frame directly contacts the vehicle frame. A baffle system is arranged to compartmentalize the total containment area and the baffle system comprises a plurality of longitudinal and transverse baffles. A top is coupled to the elongate body. 
         [0005]    In yet another exemplary embodiment, a liquid-holding tank comprises an elongate tank body. A tank frame is coupled to the elongate tank body and extends downwardly therefrom. The tank frame and the elongate tank body form a reservoir and the tank frame is adapted to rest directly on the vehicle frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    Aspects of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. 
           [0007]      FIG. 1  is a rear isometric view of the flooded-frame tank according to an exemplary embodiment. 
           [0008]      FIG. 2  is a side view of the flooded-frame tank mounted on a truck chassis according to an exemplary embodiment. 
           [0009]      FIG. 3  is a lateral cross-sectional view of the flooded-frame tank taken along line  3 - 3  in  FIG. 2 . 
           [0010]      FIG. 4  is a longitudinal cross-sectional view of the flooded-frame tank taken along line  4 - 4  in  FIG. 3 . 
           [0011]      FIG. 5  is a cut-away isometric view of a lower rear region of the flooded-frame tank according to an exemplary embodiment. 
           [0012]      FIG. 6  is a top view of the flooded-frame tank according to an exemplary embodiment with a portions of the tank partially cut away. 
           [0013]      FIG. 7  is a front isometric view of the flooded-frame tank according to an exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    This disclosure describes a novel tank design for transporting a liquid. The novel tank design has a lower vertical center of gravity as compared to conventional tank designs. In particular, a typical horizontal tank designed for transporting a liquid cannot rest directly on a truck frame, but must have framing and legs to support the tank and to attach the tank to the vehicle. In such designs, the tank&#39;s vertical center of gravity is elevated and thus impacts the vehicle&#39;s handling and safety. Thus, the novel tank design, according to one embodiment includes a structurally sound tank frame that holds liquid and is open to the tank body, thereby flooding the tank frame and lowering the vertical center of gravity. 
         [0015]    Referring to  FIG. 1 , a flooded-frame tank  100  is shown according to an exemplary embodiment in a rear isometric view. Tank  100  is generally constructed with an integral flooded frame  102  to which side walls  104  are coupled. A tank lid  106  connects side walls  104  together and functions to cover the top of tank  100 , thereby forming an elongated body. Front and rear vessel heads  108  and  110  are coupled to flooded frame  102 , side walls  104 , and lid  106  to make tank  100  leak tight. These components of tank  100  may be welded or bolted, or otherwise fastened together in a suitable manner. 
         [0016]    Referring now to  FIG. 2 , a side view of a flooded-frame tank  100 , according to an exemplary embodiment, is shown mounted on a truck chassis frame  112 . In this novel embodiment, flooded frame  102  rests directly on chassis frame  112 . Flooded frame  102  may be bottom-supported directly by chassis frame  112  without any intervening support structure between chassis frame  112  and flooded frame  102 . Since flooded frame  102  functions as a lower section of tank  100  and as a support structure of tank  100 , conventional tank legs and structural support are no longer required. The removal of traditionally required tank legs and structural support is possible through usage of novel and non-obvious structural designs and construction methods which are disclosed herein. Thus, flooded frame  102  allows the center of gravity to be lowered. In some embodiments, the reduction or lowering of the center of gravity may be as much as five inches, or more. 
         [0017]    Flooded frame  102  may be secured to chassis frame  112 , for example, by a combination of side-attached mounts  114  and  116 . Side-attached mounts  114  and  116  include spring-dampened mounts  114  and rigid mounts  116 . Each mount  114  and  116 , spans a distance from an outer vertical surface of flooded frame  102  to an outer vertical surface of chassis frame  112 . Mounts  114  and  116  couple across corresponding outer vertical surfaces of flooded frame  102  and chassis frame  112  to substantially prevent sliding and separation between flooded frame  102  and chassis frame  112 . Mounts  114  and  116  are preferably bolted to chassis frame  112  and welded to flooded frame  102 , although either may be welded or bolted, or otherwise fastened in a suitable manner. 
         [0018]    Rigid mount  116  is preferably used as the rearmost side-attached mount, and is paired with a corresponding rigid mount  116  which is similarly side-attached to an outer vertical surface of the opposite chassis frame rail (not shown). One or more pairs of spring-dampened mounts  114  are coupled at intervals along chassis frame  112 . The quantity and exact positioning of mounts  114  and  116  may be determined based on the size of the tank, by usage requirements, and on other factors. 
         [0019]    In other embodiments, straps may be used with or without mounts  114  and  116  to secure flooded frame  102  to chassis frame  112 , by side-attachment to corresponding outer vertical surfaces. In yet other embodiments, flooded frame  102  and chassis frame  112  may be secured to one another according to any suitable fastening method, with or without side-attached mounts or straps. 
         [0020]    A sill block  115 , which is preferably a thin sheet of rubber, may be installed on chassis frame  112  before tank  100  is positioned to further isolate tank  100  from road vibrations, dampen tank movements, and minimize wear of flooded frame  102 . Sill block  115  may be about one inch thick, though the thickness may be adjusted to achieve more or less vibration dampening. Other dampening devices are contemplated, such as, but not limited to, rubber or cork gaskets, wood shims, nylon pads, and the like. 
         [0021]    Front vessel head  108  is preferably flat and rear vessel head  110  is preferably dished. In other embodiments either vessel head may be flat or dished. In addition, each vessel head is preferably flanged around its perimeter. The vessel head flange (not shown) fits inside an end of the elongated body to form an overlap which may be secured by welding, for example. In other embodiments, such as for a sanitary tank, the vessel heads may be secured by butt-welding, for example, to the elongated body. 
         [0022]      FIG. 3  is a lateral cross-sectional view of flooded-frame tank  100  taken along section line  3 - 3  in  FIG. 2 . In cross-section, tank  100  may be described as having a modified square, or oval, configuration with radiused corners  105 . Flooded frame  102  comprises a generally planar flooded-frame floor  118 , which is shown in cross-section, with upwardly extending frame side walls  120 . Frame side wall flanges  122  may project transversely from frame side walls  120  and extend along the longitudinal length of flooded frame  102  to provide for attachment to tank side walls  104 . 
         [0023]    The attachment of flooded frame  102  to side walls  104  may be further strengthened by pairs of boxed gussets  123 , which may be included between flooded frame  102  and side walls  104  at the front and rear ends of tank  100 , for example. Gussets  123  may be constructed by attaching a pad  125  to flooded frame  102  and tank side walls  104 , followed by attachment of gusset  123 . Gussets  123  are attached in pairs at front and rear ends of tank  100 . Gussets  123  may also be attached to intermediate side wall locations which may or may not correspond with side wall locations supported by internal structures. Gussets  123  may also function as anti-roll stabilizers for tank  100 . 
         [0024]    Tank side walls  104  are continuously curved in this embodiment to distribute lateral forces exerted by fluid contained therein. This distribution of forces may prevent “oil canning” of side walls  104 . In other embodiments the side walls may be substantially straight, or flat; or, the side walls may comprise a profile with curved and straight sections. 
         [0025]    Tank lid  106  may attach to side walls  104  with bolts  124 . In one embodiment tank lid  106  may be formed from a single piece of material, such as sheet metal, for example, and may include generally parallel upwardly projecting, generally vertical upper channels  126 . In another embodiment tank lid  106  may comprise multiple pieces of material. In one embodiment upper channels  126  project upwardly about twelve inches, though other distances are contemplated. Upper channels  126  run longitudinally along both longitudinal sides of tank lid  106 , and may be alternatively termed gussets or ribs. In one embodiment, upper channels  126  may form side walls for mounting external lighting and may establish a conduit space  127  for running wiring. In some embodiments upper channels  126  may be full-length, segmented gussets. 
         [0026]    An end panel  130 , may be coupled between upper channels  126  (as shown in  FIG. 6 ), and conduit space  127  may be covered by a rear cap  129  (shown in  FIG. 1 ). Upper channels  126  may also provide a degree of roll-over protection for various features such as a vent pipe  162  and a service access port  176  (both shown in  FIG. 6 ). In addition, upper channels  126  may comprise sacrificial crumple zones which may absorb some of the force of a roll-over impact, thereby protecting other structural components. 
         [0027]    Tank lid  106  may further comprise a flat portion  128 , which functions primarily as a sealing cover for the top of tank  100 . In some embodiments flat portion  128  functions also as a storage platform and may be coupled to, or maybe integral with, upper channels  126 . In other embodiments, tank lid  106  may only comprise flat portion  128  without upper channels  126 . Tank lid  106  may be entirely bolted onto tank  100  such that it may be entirely removed during construction, customization, maintenance and/or inspection. Tank lid removal allows tasks such as those listed to be accomplished under reduced or eliminated confined space requirements, potentially improving safety and reducing costs. In other embodiments tank lid  106  may be welded, or other wise permanently attached. 
         [0028]      FIG. 4  is a cross-sectional view of the tank shown in  FIG. 3  taken along section line  4 - 4 . As shown in  FIGS. 3 and 4 , an interior space  132  of tank  100  may be variously divided by a baffle system  134  into smaller compartments, thereby reducing forceful liquid movements inside tank  100 . Baffle system  134  comprises two main components, transverse and longitudinal baffles. An exemplary transverse baffle  136  is shown in  FIG. 4 , extending generally laterally across the cross-section of interior space  132 . Transverse baffle  136  may be comprised of upper and lower ring sections  140  and  142 , shown in  FIG. 3 , which are made integral by being welded together. Upper and lower ring sections  140  and  142  are then connected to an internal periphery of tank  100 . Upper ring section  140  may comprise an upper flange  143 , as shown in  FIG. 4 , for coupling to tank lid  106 . Upper and lower ring sections  140  and  142  may be welded to the interior walls of tank  100  and bolted to tank lid  106 , thus allowing transverse baffle plate  144  to be centrally bolted, or otherwise coupled, to the upper and lower ring sections  140  and  142 . In some embodiments the transverse baffle plate  144  and upper and lower ring sections  140  and  142  overlap each other approximately  4  to  6  inches to allow for bolt-hole edge margins. In other embodiments, an integral ring section may be formed from more than two partial ring sections, or a monolithic baffle ring may be used. 
         [0029]    At least some of the integral, structural tank support derives from the welding of an integral baffle ring to the interior walls of tank  100 , including structural support for weight placed on tank lid  106 . In other embodiments a significant amount of strength is derived from the integral baffle ring. During manufacturing, an internal ring may be comprised of four “quadrant” ring sections to reduce material waste, for example. 
         [0030]    Transverse baffle  136  may comprise variations, perforations, holes or voids as shown in  FIG. 3 , including upper vent holes  146  for balancing pressure between divided compartments, transverse baffle service access ports  148  (see further function and description below), and fluid passages  150  for balancing fluid levels between divided compartments. As further shown in  FIG. 4 , three transverse baffles  136  are used to divide interior space  132  into lateral compartments. Other embodiments may include no transverse baffle, such as in a very small tank, for example, while still other embodiments may include one, two or more than three transverse baffles. 
         [0031]    Turning now to a description of longitudinal baffles, as shown in  FIG. 4 , at least one longitudinal baffle  138  divides interior space  132  into left and right compartments, or longitudinal segments. Longitudinal baffle  138  comprises rigid longitudinal plates  156 ,  157  and  160  connected principally to transverse baffles  136  via various brackets  158 . Forward and rear longitudinal plates  156  and  157  are bolted to the front and rear vessel heads  108  and  110 , respectively. A vertical vent pipe  162  may also provide support for attachment of brackets  158  which support longitudinal plates  156  and  160 . Brackets  158  may contain elongated slots  164 , such that a longitudinal plate bolt hole may adjustably align over an elongated slot  164  permitting a bolt to be inserted transversely to couple the parts. Elongated slots  164  allow for easier fit-up during manufacturing and/or maintenance. Longitudinal plates  160  may be sized to increase ease of material handling during installation and repair as each longitudinal division between transverse baffles  136  may be comprised of multiple longitudinal plates  160 . Longitudinal plates  160  may further be sized to increase material yield during manufacturing. For example, longitudinal plates  160  may be manufactured in quadrants to reduce scrap during manufacturing. In other embodiments, the longitudinal plates  160  may be monolithic, and may be welded or held in position by other suitable fastening means. 
         [0032]    In addition to having the assembly and material usage advantages described above, the novel assembly of baffle system  134  may provide a benefit against corrosion, especially microbial induced corrosion. Material properties in areas near a weld, which are typically larger than the weld itself, may be negatively affected by the welding process. For example, a heat affected zone created by welding stainless steel may significantly reduce corrosion resistance, especially along the edges of the weld. Thus, by using mechanical fasteners, such as threaded fasteners, for example, baffle system  134  may be more resistant to corrosion at attachment interfaces. In some embodiments, a laminating protection may be applied to the tank interior surfaces and components. 
         [0033]      FIG. 5 , is a cut-away isometric view of an exemplary lower rear region of tank  100 . Since structural tank support is integral to tank  100 , no external supports are required for attachment of flooded frame  102  to chassis frame  112  (shown in  FIG. 2 ). At least some of the integral, structural tank support derives from the coupling of a strap  152  to a lower edge of transverse baffle  136 . Strap  152  may be formed to match a lower edge profile of transverse baffle  136 . Strap  152  may then be welded to the lower edge of transverse baffle  136 , thereby create a lower baffle flange  154 . Lower baffle flange  154  may be T-shaped in cross-section, and may be welded to flooded frame  102 . Strap  152  and transverse baffle  136  may be welded together, as mentioned, or a lower baffle flange  154  may be created by another process such as machining a flanged ring from a solid block, casting, and the like. Strap  152  and transverse baffle  136  may be similarly combined with or without additional components to provide other structurally significant cross-sections, such as an L-shape, a J-shape, and the like. In embodiments where transverse baffle  136  comprises a transverse baffle plate  144  and a lower ring section  142 , a lower baffle flange  154  may be constructed by welding a strap  152  to a lower edge of lower ring section  142 . Strap  152  may also function as a doubler, or backup pad, to distribute the force of the lower edge of transverse baffle  136 , or the force of the lower edge of ring section  142 . 
         [0034]    Referring again to  FIG. 4 , a full-through venting system  166  is provided to reduce or eliminate vacuum that may be created by draining liquid.  FIG. 4  shows vertical vent pipe  162  located near front vessel head  108 . Vent pipe  162  extends upwards through a penetration in tank lid  106  and downwards to a flange  168  near flooded-frame floor  118 . The extension distance of vent pipe  162  above tank lid  106  is preferably about three inches. The extension distance may also be more or less than three inches. If the extension distance is more than three inches, it should still be less than the vertical projection of upper channels  126 . A longitudinally oriented, closed vent trough  170  is coupled to flange  168 . Vent trough  170  generally extends between flange  168  and flooded-frame floor  118 , and may extend rearward along flooded-frame floor  118  past the last vehicle axle. Vent trough  170  is sealed to flange  168  of vent pipe  162  and closed all the way around. Vent trough  170  is open to the atmosphere underneath tank  100  via a hole  171  in flooded-frame floor  118 .  FIG. 5  shows hole  171  through a cut away in vent trough  170 . Hole  171  preferably has a diameter of about six to about eight inches, although other shapes and dimensions are contemplated. 
         [0035]    Referring now to  FIG. 6 , a top view of tank  100  is shown according to an exemplary embodiment with portions of the tank partially cut away. Towards the front end of tank  100  a service access port  176  is included which is open to interior space  132 . Service access port  176  is covered by a removable grating  177  which may have about one inch spacing. An overflow basin  173  surrounds both service access port  176  and grating  177 . Overflow basin  173  may be covered by a basin lid  175  which may be hinged and latched. Basin  173  may be comprised of an entirely separate enclosure or may be comprised of components such as upper channel  126 , end panel  130  and a lateral divider  184 . Lateral divider  184  may be coupled between upper channels  126  similar to end panel  130 . In addition, basin  173  may be about  24  inches wide and about 30 inches long. Turning briefly to  FIG. 7 , an alternative embodiment is shown with basin  173  comprised of upper channel  126 , end panel  130 , a lateral basin wall  186 , and a longitudinal basin wall  188 . In other embodiments basin lid  175  is not required. In another embodiment, grating  177  comprises a vented basket that drops a few inches into tank  100 . 
         [0036]    During draining, as fluid volume rapidly decreases inside tank  100 , air from outside tank  100  is sucked into venting system  166  to fill the fluid-evacuated volume, thereby allowing fluid to drain without creating a potentially damaging vacuum inside tank  100  that may restrict fluid draining and adversely impact the structure of tank  100 . Venting air enters through hole  171 , travels through vent trough  170  and vent pipe  162 , and enters the tank through grating  177 , such that tank  100  is constantly vented. In other embodiments, vent pipe  162  and service access port  176  may be together located at alternate positions such as near the middle or towards the rear of tank  100 . The positioning of vent pipe  162  and service access port  176  near the front of the tank may function to reduce liquid spillage due to closer placement to a mid-point of the vehicle wheel base. Flexibility of positioning vent pipe  162  and service access port  176  may be enhanced by locating and extending vent trough  170  along the bottom of tank  100 . However, in other embodiments, a vent trough may be located above the bottom of tank  100  or positioned left or right of a longitudinal midline. 
         [0037]    During filling of tank  100 , an overfill condition may arise when fluid rises above grating  177  and fills basin  173 . Excess fluid is able to exit basin  173  by entering vent pipe  162 , traveling along vent trough  170 , and exiting through hole  171 . Fluid may be prevented from shooting upwards by basin lid  175 . During abrupt stops, fluid may slosh forward and partially fill basin  173 . If the fluid rises above vent pipe  162 , then the fluid is directed to safely exit through hole  171  behind the last wheels. Removable grating  177  may also provide quick access for liquid filling and removal. 
         [0038]    As described above, and as shown in  FIG. 5 , liquid may drain, or dump, from flooded frame  102  to transverse drain trough  172 , which opens on either side of tank  100 . The liquid may also drain through a dump valve flange  174  which opens to the rear of tank  100 . In some embodiments, tank  100  may have a drain comprised of a single dump valve opening, which may be either side- or rear-exiting. Venting air may also enter through the dump valves  172  and  174  during draining. In another embodiment rearmost gusset  123  has a reduced width because a part of its function is accomplished with transverse drain trough  172 . 
         [0039]    Service access, in addition to that mentioned briefly above with respect to removable tank lid  106 , is now described referring to  FIG. 6 . Basin lid  175  is lifted and grating  177  removed to access service access port  176 , which provides access to at least one compartment inside tank  100 . From this first compartment, service access to other compartments is obtained through transverse baffle service access ports  148  (shown in  FIG. 3 ) formed in transverse baffle plates  144 , and in another embodiment, by one or more hinged longitudinal baffle service access panels (not shown). 
         [0040]    Referring to  FIG. 3 , transverse baffle service access port  148  may be provided by cutting or punching a circular, scalloped-shaped opening, which may be a shape such as a circle ringed by an array of radially extending rectangles or tabs. The punched or cut-out scalloped-shaped coupon may then be rotated and coupled over service access port  148  as an access cover  178 . Voids  180  left in the transverse baffle plate  144  by the removal of radially extending rectangles or tabs may be sized to permit fluid controlled flow between lateral compartments. Voids  180  may also be sized to enable a service person to pass a hand or arm though to aid in the removal or fastening of mechanical fasteners holding access cover  178  in place. Pairs of transverse baffle service access ports  148  may be provided in each transverse baffle  136 . In other embodiments, transverse baffle service access ports  148  may have different shapes such as oblong and square, among others, and access cover  178  may have one or more radially projecting tabs. 
         [0041]    Referring to  FIG. 7 , a front isometric view of flooded-frame tank  100  is shown according to an exemplary embodiment. Tank lid  106  is shown in a storage configuration with upper channels  126  spaced approximately four feet apart to form side walls for a storage area  182 . Storage area  182  may be further defined by lateral divider  184  and a longitudinal divider  185 . In addition, when not functioning as part of basin  173 , dividers  184  and  185  may be adjustable to make storage area  182  user-configurable. Storage area  182  may include a cargo tie down system (not shown). As configured in  FIG. 7 , storage area  182  may be used to store implements and supplies. For example, a fire hose (not shown) may be stored in a vertical or horizontal accordion pattern on tank lid  106  between either upper channel  126  and longitudinal divider  185 . 
         [0042]    As shown in  FIG. 7 , head channels  202  are secured at an angle to front vessel head  108 . In cross-section, each channel  202  may be a hat-channel, though other cross-section are contemplated. An upper end of channel  202  overlaps a front cap  198  which covers conduit space  127  by coupling to the front end of upper channel  126 . Front cap  198  has a lower opening, created from formation of a tab  204 . Tab  204  covers the channel opening at the upper end of channel  202 , thereby establishing a protected path between conduit space  127  and channel  202 . A lower end of channel  202  is open. In other embodiments, the front vessel head may be dished and may comprise channels  202  that have been contoured to approximate the dished curve of the head. 
         [0043]    Channels  202  may function to strengthen front vessel head  108 , especially against oil-canning. In addition, channels  202  may function to protect, conceal, and guide wires between the conduit space  127  and the underside of the tank by allowing wires to travel through conduit space  127 , out through the lower opening in front cap  198 , into channel  202 , and down to the bottom of the tank. Electrical wiring in conduit space  127  may be accessed by removing front or rear caps  129  and  198 , or by removing an outer wall of upper channel  126 . In other embodiments, channels  202  may support control panels, accessories, or auxiliary systems. 
         [0044]    Optional outriggers  190  may extend laterally from flooded frame  102  and provide further equipment attachment points, such as for tool boxes and the like. Outriggers  190  may be constructed by attaching a pad  192  to flooded frame  102 , followed by attachment of an outrigger beam  194  and an angled support bracket  196  to pad  192 . 
         [0045]    Other additional embodiments and alternatives are contemplated for various features of tank  100 . According to one embodiment, an internal width of tank  100  is about 77 inches with an internal height of about  59  inches. Other dimensions for internal and external sizing are contemplated to meet payload requirements or access restrictions. Tank  100  can be constructed of various materials including steel, stainless steel, aluminum, plastics, fiberglass and composites. 
         [0046]    Although embodiments of the present disclosure have been described in detail, those skilled in the art should understand that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure. Accordingly, all such changes, substitutions and alterations are intended to be included within the scope of the present disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures.