Abstract:
A rail gauge face applicator is provided. The gauge face applicator comprises a resilient pad comprising one or more than one channel extending from one or more than one inlet to one or more than one outlet. The one or more than one channel is operable from a closed position when the pressure within the channel is low to an open position when the pressure within the channel is raised. Thus, when the pressure of the friction modifying material is raised the one or more than one channel opens and material can be delivered from the one or more than one outlet. The applicator further comprises a rail engagement element which allows the gauge face applicator to be positioned appropriately to engage a rail. The applicator may be less prone to clogging and may be more efficient at delivering friction modifying material efficiently than prior art applicators.

Description:
TECHNICAL FIELD 
     The present disclosure pertains to an apparatus and methods for applying lubricants or other friction modifiers to the gauge face of railroad rails. 
     BACKGROUND 
     In the operation of railroads, grease or other friction modifiers are applied onto railroad rails, such as to the top of rails or gauge face of rails at curves, turnouts, switches, in some cases, the sections of the track immediately before a switch, and periodically spaced along the length of the track. Such lubricants and friction modifying materials can either reduce or increase the friction where necessary to improve train performance, reduce wheel squeal, reduce wear on both the rails and the train wheels, or a combination thereof. Devices and methods for applying friction modifying materials to top of rail or gauge face rail surfaces include, for example, US 2008/0223661; GB 2,446,949; U.S. Pat. Nos. 2,821,263; 5,348,120; 5,394,958; 6,009,978; 6,742,624; 7,121,383; WO 2010/033900; WO 2010/138819 (these documents are herein incorporated by reference). 
     Rails have a head portion, a base portion, and a web portion extending between the head portion and the base portion. The head portion defines an outer surface comprising a top surface a field facing surface, and a gauge face surface. Lubricant or other friction modifying material may be applied to the top of rail, gauge face surface, or to both surfaces, as these locations contact the train wheels. However, the material may not always reach the desired location which can reduce the efficacy of friction modification. The material may also be wasted by dripping or flowing to a location where it does not perform its function optimally. The presence of this waste friction modifying material can cause undesirable safety, maintenance, or environmental issues. Apparatus for application of material can be prone to clogging or otherwise being impaired in their performance due to an accumulation of dirt or other residue. 
     SUMMARY 
     The present disclosure pertains to an apparatus and methods for applying lubricants or other friction modifiers to the gauge face of railroad rails. 
     Embodiments of the present disclosure provide a rail gauge face applicator comprising, a pad or body, for example a resilient pad or body, comprising one or more than one channel extending from one or more than one inlet to one or more than one outlet. The one or more than one channel is operable from a closed position when the pressure within each of the one or more channels is low to an open position when the pressure within each of the one or more channels is raised. Thus, when the pressure of the friction modifying material is raised each of the one or more channels opens and material can be delivered from the one or more outlets to the gauge face surface of a rail. The applicator also comprises a rail engagement element which may facilitate positioning the gauge face applicator to engage a gauge face surface of the rail. The resilient pad when mounted against the rail engagement element is compressed so that at least a portion of each of the one or more than one channel within the resilient pad is closed. The portion of each of the one or more channels that is closed may be the outlet or a portion of the channel adjacent the outlet. For example, the resilient pad may be compressed from between about 0.5% to about 20% along a first width, a second width or a combination thereof, of the resilient pad. The width that is compressed may be the first width between one side surface to a second side surface of the resilient pad, the second width between a top surface to a bottom surface of the resilient body, or a combination thereof. The resilient foam bar may comprise, for example from between 1 to about 24 channels, inlets and outlets. 
     The rail engagement element may also be positioned to extend beyond a top surface of the resilient pad. For example the rail engagement element may extend beyond the top surface from between about 0.01 to about 50 mm. The positioning of the rail engagement element beyond that of the top surface of the resilient pad may facilitate direction of the friction modifying material from each of the one or more outlets to the gauge face surface of the rail. Furthermore by extending the rail engagement element beyond the top surface of the resilient body the resilient pad of the applicator may be positioned at a location along the gauge face surface of the rail that is lower (relative to the ground surface) than would otherwise be possible if the rail engagement element is not present, while still effectively delivering friction modifying material to the gauge face surface. 
     The use of the rail engagement element may also simplify mounting and adjustment of the assembled applicator against rails comprising worn gauge face or top of rail surfaces, while still achieving effective delivery of the friction modifying material to the gauge face of the rail with reduced waste. 
     The gauge face applicator may further comprise one or more than one port in fluid communication with the one or more than one inlet so that each of the one or more than one channel is in fluid communication with one or more than one port. Each of the one or more ports may also be connected to, and be in fluid communication with, a friction modifying delivery system. The one or more than one port may be mounted on an applicator support positioned along a bottom surface of the resilient foam bar. The applicator support configured to permit attachment of the gauge face applicator to a rail or rail bed. 
     The gauge face applicator as described herein may be less prone to clogging and more efficient at delivering friction modifying material efficiently than prior art applicators thereby saving costs associated with friction modifying material, reducing waste of the material, and reducing rail maintenance. 
     Embodiments of the present disclosure provide a gauge face applicator comprising a compressible foam bar and a rail engagement element, the bar having a one or more inlets, one or more outlets, and one or more channels extending from the one or more inlets to the one or more outlets, the bar compressed against the rail engagement element such that each of the one or more channels is closed to significant flow of friction modifying material but that increasing the flow pressure of the friction modifying material causes one or more of the one or more channels to open and friction modifying material to flow onto a gauge face surface of a rail. The rail engagement element may be positioned to extend beyond a top surface of the resilient pad as described above. The assembled applicator may be easily installed and adjusted as a modular unit simplify mounting and adjustment of the assembled applicator against rails. As noted above, the applicator may also be installed against rails comprising a worn gauge face or top of rail surfaces, while still achieving effective delivery of the friction modifying material to the gauge face of the rail with reduced waste. The gauge face applicator may further comprise one or more ports in fluid communication with the one or more inlet. The one or more port may also be connected to, and be in fluid communication with, a friction modifying delivery system. The one or more port may be mounted on an applicator support positioned along a bottom surface of the resilient foam bar. The applicator support configured to permit attachment of the gauge face applicator to a rail or rail bed. The resilient foam bar may comprise for example, from between 1 to about 24 channels, inlets and outlets. Each of the one or more than one inlets in fluid communication with one or more than one port. 
     Embodiments of the present disclosure provide a use of a gauge face applicator as described herein for delivering friction modifying material to a gauge face surface of a rail. 
     Embodiments of the present disclosure also provide a method of applying friction modifying material to a gauge face of a rail, the method comprising providing a gauge face applicator positioned against the gauge face surface, the applicator comprising a resilient pad and a rail engagement element, the resilient pad having one or more friction modifier flow channels extending from one or more inlets to one or more outlets the resilient pad compressed against the rail engagement element so that at least a portion of each of the one or more friction modifier flow channels within the resilient pad is closed when a fluid pressure within the friction modifier flow channel is low; and applying friction modifying material to the gauge face surface of a rail by raising the fluid pressure in one or more of the one or more friction modifier flow channels causing the one or more friction modifier flow channels to open and friction modifying material to be distributed to from the outlet to the gauge face of the rail. The portion of the friction modifier flow channel that is closed may be the outlet, or a portion of the friction modifier flow channel adjacent the outlet. 
     Embodiments of the present disclosure provide a rail gauge face applicator comprising, a resilient pad attached to an applicator support along a bottom surface of the resilient pad, and a rail engagement element, the resilient pad comprising one or more channels extending from one or more inlets at the bottom surface or a first side surface, to one or more outlets at a top surface or a second side surface adjacent the top surface, each of the one or more channels in fluid communication with one or more port within the applicator support, the applicator support for attachment to the rail or rail bed, the one or more outlet operable from a closed position when low fluid pressure is present in each of the one or more channels, to an open position when the fluid pressure increases within one or more of the one or more channel, the rail engagement element adjacent the second side surface of the resilient pad. The resilient pad, when mounted against the rail engagement element, is compressed so that at least a portion of one or more of the one or more channel within the resilient pad is closed. The portion of the channel that is closed may be the outlet or a portion of the channel adjacent the outlet. For example, the resilient pad may be compressed from between about 0.5% to about 20% along a first width, a second width or a combination thereof, of the resilient pad. The width that is compressed may be the first width between the first side surface to the second side surface of the resilient pad, the second width between the top surface to the bottom surface of the resilient body, or a combination thereof. The rail engagement element may also be positioned to extend beyond the top surface of the resilient pad. For example the rail engagement element may extend beyond the top surface from between about 0.01 to about 50 mm. The positioning of the rail engagement element beyond that of the top surface of the resilient pad may facilitate direction of the friction modifying material from the friction modifying outlet to the gauge face surface of the rail. The one or more port may also be connected to, and be in fluid communication with, a friction modifying delivery system. 
     The present disclosure also provides a resilient pad cassette comprising a resilient pad comprising one or more than one channel extending from one or more than one inlet to one or more than one outlet, the resilient pad attached to an attachment plate, the attachment plate defining one or more than one opening in fluid communication with the one or more than one inlet. The attachment plate comprising one or more than one attachment mechanism for attaching the resilient pad cassette to the support. 
     The present disclosure also provides a method of replacing a resilient pad of the gauge face applicator as defined above comprising, removing the resilient pad from the applicator support and the rail engagement element and, compressing a resilient pad cassette, comprising a replacement resilient pad attached to an attachment plate against the rail engagement element, and attaching the attachment plate to the applicator support thereby replacing the resilient pad. 
     By extending the rail engagement element beyond the top surface of the resilient body the resilient pad of the applicator may be positioned at a location along the gauge face surface of the rail that is lower (relative to the ground surface) than would otherwise be possible if the rail engagement element is not present, while still effectively delivering friction modifying material to the gauge face surface. The use of the rail engagement element may also simplify mounting and adjustment of the assembled applicator against rails comprising worn gauge face or top of rail surfaces, while still achieving effective delivery of the friction modifying material to the gauge face of the rail with reduced waste. 
     The gauge face applicator as described herein provides a simple design with few parts. Furthermore, using a reduced number of outlets, for example from about 1 to about 10 outlets, assists in keeping the friction modifying material flowing uniformly through the delivery system. As the one or more outlets within the resilient pad of the applicator are closed when the fluid pressure within the one or more channels is low, the outlets self-clean and reduce contaminants from entering the outlets thereby reducing clogging. This may permit the use of additional outlets, for example from about 10-60 outlets, along the resilient foam bar while reducing the incidence of clogging within the outlets. 
     As used herein, the term “friction modifying material” refers to material which can functionally change the amount of friction between a rail and a wheel and are well known in the art. The material may increase or decrease the amount of friction depending on the particular material and circumstances. Examples of friction modifying materials include but are not limited to those described in WO0225919, EP1418222, EP1807489, U.S. Pat. No. 6,759,372 (which are incorporated herein by reference). 
     As used herein, the term “rail engagement element” may take any suitable form such as a thin blade that sits flush against the gauge face of the rail. 
     As used herein, directional terms such as “top”, “bottom”, “left”, “right”, “front”, and “rear” are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment. 
     This summary does not necessarily describe all features of the invention. Other aspects, features and advantages of the invention will be apparent to those of ordinary skill in the art upon review of the following description of specific embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will be described in conjunction with reference to the following drawings in which: 
         FIG. 1  is a side view of an applicator according to one embodiment of the present disclosure; and 
         FIG. 2  is a perspective view of the applicator of  FIG. 1 . 
         FIG. 3A  shows an example of a cross section of a resilient pad. A non-limiting example of a channel within the resilient pad is also shown.  FIG. 3B  shows a side view of several components of an example of an applicator, showing a non-limiting example of a resilient pad comprising a channel mounted onto one surface of a support, and a port mounted on a second surface of the support.  FIG. 3C  shows a front view of a rail engagement element comprising openings for mounting the rail engagement element onto the support. 
         FIG. 4A  shows a top view of a non-limiting example of a resilient pad comprising four channels.  FIG. 4B  shows a back view of the resilient pad of  FIG. 4A . The outlets of the channels are shown on a surface of the resilient pad.  FIG. 4C  shows a top view of a several components of an example of an applicator, including a non-liming example of a resilient pad, a rail engagement element, a support, and four ports.  FIG. 4D  shows a front view of the components of the applicator shown in  FIG. 4C . 
         FIG. 5A  shows a back view of a non-limiting example of a resilient pad comprising one elongate channel. An outlet is shown on a surface of the resilient pad.  FIG. 5B  shows a top view of the resilient pad of  FIG. 5A .  FIG. 5C  shows a front view of a several components of an example of an applicator, including a non-limiting example of a resilient pad, a rail engagement element, a support, and one port.  FIG. 5D  shows a top view of the components shown in  FIG. 5C . 
         FIG. 6A  shows a side exploded view of components of an example of an applicator, including a resilient pad, a rail engagement element, a support, port and mounting bolts.  FIG. 6B  shows a side view of a assembled applicator showing a non-liming example of a resilient pad comprising a channel, a rail engagement element, a support, and a port, mounted to a bar chassis. 
         FIG. 7   a  shows an exploded perspective view of a resilient pad cassette including a resilient pad and attachment plate.  FIG. 7B  shows a cross section of the resilient pad cassette of  FIG. 7A  mounted onto a support. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure pertains to an apparatus and methods for applying lubricants or other friction modifiers to the gauge face of railroad rails. 
     Referring to  FIG. 1 , one embodiment of a rail applicator assembly  10  is shown. The rail applicator assembly  10  may be mounted to a railroad rail  12  and includes an applicator  40  for applying a friction modifying material to a gauge face  26  of the rail  12 . The rail  12  includes a base portion  14  with flanges  16  extending therefrom and a head portion  18  having a web portion  20 , which extends between the head portion  18  and the base portion  14 . The head portion  18  of the rail  12  has an outer surface  22  defining a crown  24 , or top of rail and a gauge face surface  26 . The applicator  40  is configured to apply friction modifying material to the gauge or inside surface  26  (hereafter the “gauge face”) of the rail  12 . 
     The applicator  40  includes a resilient pad  28 , having a front surface  30  and a rear surface  32 , a rail engagement element  38 , and an applicator support  34  for supporting and attaching the applicator  40  to the rail  12 , and for positioning and supporting the applicator  40  adjacent to the gauge face  26  of the rail  12 . 
     The resilient pad  28  is an elongate member generally having a rectangular shape, although other suitable shapes may be utilized for the pad  28 . The pad  28  defines one or more than one channel  36  that extends through the pad  28  for the friction modifying material to flow from one or more than one inlet  36   a  to one or more than one outlet  36   b .  FIGS. 4A ,  4 B,  5 A and  5 B show examples of resilient pads comprising 4 ( FIGS. 4A , B) or one channel ( FIGS. 5A , B). The channel may be elongated along the length of the pad  28 , so that the inlet  36   a  and outlet  36   b  are slot-shaped (see FIGS.  5 A,B) The channel  36  may be directly formed in the pad  28 . Alternatively, the channel  36  may be defined by a separate insert (not shown) positioned within the pad  28 . The pad  28  may be constructed of any resilient material, for example but not limited to an open-cell neoprene foam, a polymeric material, rubber, stone wool, a closed-cell foam, or a combination of open-cell and closed-cell foam. For example, a profiled or shaped rubber pad, for example, a hollow rubber member having sufficient resiliency and flexibility may be used as the pad  28 . Alternatively, the rubber member may comprise a preformed channel with a closure or valve member at the outlet. A cross section of an example of a resilient pad  28  in an uncompressed state comprising a channel  36  is shown in  FIG. 3A . In the uncompressed state, channel  36  is open along the length of the channel from the inlet  36   a  to the outlet  36   b.    
       FIG. 3B  shows several components of applicator  40  in a partially assembled state, including resilient pad  28  comprising one or more channels  36 , mounted onto an upper surface of support  34 . The resilient pad  28  may be glued onto support  34 , or attached to support  34  via clips, or keys and with corresponding passageways or press-fit as would be known within the art. Inlet pipe  300 , attached on the lower surface of the support  34 , is also shown. Inlet pipe  300  is in fluid communication with opening  35  within support  34  and with channel  36 . The free end of inlet pipe  300  is for attachment to a friction modifying material delivery system as is known in the art. The resilient pad  28  in  FIG. 3B  is shown in an uncompressed state with the back surface of the pad  30  extending beyond the back side of support  34 , by an amount  34   a.    
     The resilient pad  28  may be removed from the applicator, and replaced, under field conditions if the resilient pad wears over time. This would involve removing the resilient pad  28  from the support  34 , and re-attaching a new resilient pad to the support. For example, if the resilient pad is glued on the support directly, then the upper surface of the support is cleaned with a suitable solvent, an adhesive is applied to the surface(s) to be glued, and the resilient pad  28  reattached to the support while compressing the pad against the rail engagement element  38 . If the pad is attached by clips, keys or by another mechanical attachment mechanism, then the pad may be removed and reinstalled using the same attachment mechanism while compressing the pad against the rail engagement element. Alternatively, a resilient pad cassette, comprising a resilient pad  28  glued, or otherwise attached, to an attachment plate  28   d  (see  FIGS. 7A and 7B ). The attachment plate  28   d  may be fastened, for example by bolts  28   c  into the support  34 . The attachment plate  28   d  comprises one or more opening  28   b  in fluid communication with one or more channel  36 . As shown in  FIG. 7B , the width of resilient pad  28  is greater than that of attachment plate  28   d  so that when the assembly is mounted against rail engagement element  36 , the resilient pad within the cassette may be compressed by amount  34   a.    
     The rail engagement element  38  (see  FIG. 3C ), for example, a thin blade, is attached to an applicator support  34  ( FIG. 1 ,  6 A,  6 B). The side surface of the rail engagement element  38  abuts the front surface  30  of the pad  28 . An example of a rail engagement device  38  comprising one or more openings for mounting onto a support  34  is shown in  FIG. 3C . 
     The applicator support  34  may be attached to the rail  12  using any suitable mounting. For example as shown in  FIGS. 1 , and  6 B, the applicator support  34  may be connected to a bar chassis  50  with fasteners  41 . 
     When the applicator  40  is installed on a rail using support  50 , the rail engagement elements or thin blade  38  extends upwards from the applicator support  34  and engages with the gauge face  26  of the rail. The rail engagement element  38  may be positioned to extend beyond the top surface of the resilient pad  28  (see  38   a    FIG. 6B ). For example the rail engagement element  38  may extend beyond the top surface of the resilient pad  28  from between about 0.01 to about 50 mm or any amount therebetween. For example, the rail engagement element  38  may extend beyond the top surface of the resilient pad  28  from about 0.01 0.05, 1.0, 1.5, 2.0, 2.5, 5.0, 7.5, 10.0, 12.5, 15, 17.5, 20, 22.5 25, 27.5, 30, 35, 40, 45, and 50 mm or any amount therebetween. 
     The positioning of the rail engagement element beyond that of the top surface of the resilient pad may facilitate direction of the friction modifying material from each of the one or more outlets  36   b  to the gauge face surface of the rail  26 . Furthermore by extending the rail engagement element  38  beyond the top surface of the resilient body  38 , the resilient body  38  of the applicator  40  may be positioned at a location along the gauge face surface of the rail  26  that is lower (relative to the ground surface) than would otherwise be possible if the rail engagement element  38  was not present, while still effectively delivering friction modifying material to the gauge face surface  26 . 
     The use of the rail engagement element  38  may also simplify mounting and adjustment of the assembled applicator  40  against rails that are worn and comprise worn gauge face  26  or top of rail  24  surfaces, while still achieving effective delivery of the friction modifying material to the gauge face of the rail with reduced waste. 
     Bar chassis  50  may comprise an extension  54  which extends away from the rail  12 . The extension  54  connects the bar chassis to mounting clamp  44 . Each applicator  10  may have more than one bar chassis  50  connected to more than one mounting clamp  44 . For example, the bar chassis  50  may be mounted to the rail  12  through two mounting clamps  44 . Each of the mounting clamps  44  has a recess  46  configured to receive the flange  16  of the rail  12 . Each mounting clamp  44  also includes a bolt (not shown) having a J-shaped end configured to receive the flange  16  and a threaded end that passes through the mounting clamp  44 . 
     The resilient pad  28  is attached to the applicator support  34  and abuts the rail engagement element  38 , so that it is compressed against the rail engagement element  38 . When the resilient pad is compressed, at least a portion of the one or more than one channel  36  is closed. For example, which is not to be considered limiting, as shown in  FIG. 1 , the one or more than one outlet  36   b  of the one or more than one channel may be closed. However, if desired, the length of the one or more than one channel  36 , from the inlet  36   a  to the outlet  36   b  may be closed. The resilient pad may be compressed from between about 0.5% to about 20% of the width of the resilient pad, along a first width, a second width or a combination thereof, of the resilient pad. The width that is compressed may be the first width between one side surface, for example surface  32 , to a second side surface, surface  30  of the resilient pad, the second width between a top surface to a bottom surface of the resilient body, or a combination thereof. For example, the resilient pad may be compressed from between about 0.5, 1.0, 2.0, 4.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0, 18.0, and 20% along the first width, second width, or a combination thereof. 
     It is also contemplated that resilient pad  28  may be mounted on support  34  and abutted against rail engagement element  38  in a way that the resilient pad is not compressed against the rail engagement element. In this example, the outlet  36   b  of resilient pad comprises a self closing valve, so that when the fluid pressure of the friction modifying material within channel  36  is low, the self closing valve is closed. The self closing valve would open with increased pressure within channel  36  permitting the friction modifying material to exit the channel. A self closing valve may be manufactured as part of the resilient pad, for example flaps along the upper surface of the resilient pad at the outlet  36   b , or a self closing valve may be inserted within the outlet  36   b , for example, press fit or snap fit into the resilient pad  36  at outlet  36   b.    
     The resilient foam bar may comprise, for example from between 1 to about 24 or any amount therebetween of channels, inlets, outlets, or any combination thereof. For example 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24 channels, inlets, outlets, or any combination thereof.  FIGS. 2 ,  4 C and  4 D shows an example of an assembled applicator mounted on support  50  comprising four inlet pipes  300 .  FIGS. 5C and 5D  show an assembled applicator mounted on support  50  comprising one inlet pipe  300   
     In operation a pump (not shown) is activated and impels friction modifying material through the flow channel  36  from the inlet  36   a  to the outlet  36   b . The friction modifying material is delivered to the pad  28  and rail engagement device  38  for application on the gauge face  26  of the rail  12 . Once the pump is deactivated the fluid pressure within one or more of the one or more than one channel  36  decreases and one or more than one of the channel  36  closes reducing the chance of contamination or clogging. 
     The pad  28  is secured to the upper surface of the applicator support  34 . For example, the pad  28  may be directly formed on or bonded to the applicator support  34 . The applicator  40  and applicator support  34  may be mounted to rail  12  for example using mounting clamps  44 . In this example, each of the mounting clamps  44  comprises a recess  46  configured to receive the flange  16  of the rail  12 . However, other mounting systems may be used if desired. 
       FIG. 2  shows a perspective view of the rail applicator assembly  10  of  FIG. 1 , the applicator  40  includes the pad  28  and the rail engagement element  38 . The corner of the pad  28  is canted  28   a . The corner of the rail engagement element  38  is also canted  38   a . This allows the pad  28  and the rail engagement element  38  to engage the train wheel (not shown) with a lower risk of damage ensuing. There are two mounting clamps  44 . Also shown are four inlet pipes  300  which are in fluid communication with the inlet  36   a  to the flow channel  36 . 
     It is contemplated that any embodiment discussed in this specification can be implemented or combined with respect to any other embodiment, method, composition or aspect of the invention, and vice versa. 
     Unless defined otherwise, all technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this invention belongs. Unless otherwise specified, all patents, applications, published applications and other publications referred to herein are incorporated by reference in their entirety. If a definition set forth in this section is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications and other publications that are herein incorporated by reference, the definition set forth in this section prevails over the definition that is incorporated herein by reference. Citation of references herein is not to be construed nor considered as an admission that such references are prior art to the present invention. 
     Use of examples in the specification, including examples of terms, is for illustrative purposes only and is not intended to limit the scope and meaning of the embodiments of the invention herein. Numeric ranges are inclusive of the numbers defining the range. In the specification, the word “comprising” is used as an open-ended term, substantially equivalent to the phrase “including, but not limited to,” and the word “comprises” has a corresponding meaning. 
     The invention includes all embodiments, modifications and variations substantially as hereinbefore described and with reference to the examples and figures. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims. Examples of such modifications include the substitution of known equivalents for any aspect of the invention in order to achieve the same result in substantially the same way.