Abstract:
A device for extending the life of a tire and providing a new tread layer, principally for off road truck tires, has a mechanically attached surface tread of rubber blocks cooperatively connected with a cable system and specialized tensioning. The apparatus is generally suited to tires of very large size, typically used on dump trucks in open pit mining applications.

Description:
TECHNICAL FIELD 
     Implementations discussed herein are related to new or replacement tire retread layers. 
     BACKGROUND 
     Haul trucks used in the mining industry require large tires and these tires are often replaced semi-annually. A typical mining haul truck generally requires six tires that represent a replacement cost of over $100,000 per tire, and are replaced twice annually. Therefore, a single typical haul truck requires a tire replacement expense exceeding $1.2 million annually. In the Powder River Basin of Wyoming, which is mined extensively for coal, there is estimated to be 500 of these trucks. In the northeast corner of Wyoming alone, it is estimated that over 500 million dollars annually is spent on replacement tires. 
     Discarded and stockpiled tires are an environmental and health risk. They are very heavy (often over 3 tons per tire) and replacement requires expensive “downtime” for the haul truck. The problem is compounded significantly considering the number of these trucks across the country—or world—and the increasing demands placed on natural rubber harvest. As demands upon virgin rubber escalate, alternatives to single piece tires must be developed. 
     Most extended tire wear systems are known as “retreads” which attempt to adhere a new tread surface to an existing worn tire or carcass. These applications are directed at vehicles that may travel at high speeds on pavement, and are susceptible to failure under high heat and stress. Retention of two-piece tires under flexure, loading, and rotation is a continuing problem. 
     The information included in this Background section of the specification, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not to be regarded subject matter by which the scope of the invention is to be bound. 
     SUMMARY 
     Implementations discussed herein are directed to a tire tread device with fasteners to securely restrain the tire tread device to a worn tire or carcass under heavy equipment operations. Under the flexure of tires, during rotation with heavy load, the disclosed tire tread device may restrain and prevent independent movement of the tread device from a worn tire or carcass in which it is mounted. Implementations discussed herein provide for better internal heat dissipation and attachment to a tire without separation. 
     A reliable and strong support structure for a replacement tire tread is disclosed. Individual tire tread pads may be mechanically attached to a worn tire or carcass with barbed attachments. A cable system in which cables are embedded within the tread pads further restrains the tread pads around the tire. The cable system may transfer forces in tension, but not in compression. The cables may compress at the leading and trailing edge of the tire footprint during tire rotation under high load. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. A more extensive presentation of features, details, utilities, and advantages of the present invention is provided in the following written description of various embodiments of the invention, illustrated in the accompanying drawings, and defined in the appended claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is an isometric view of an implementation of a tire retread apparatus attached to a tire. 
         FIG. 2  is a top isometric view of rubber tread section. 
         FIG. 3  is a schematic view of a typical spike in a rubber tread section. 
         FIG. 4A  is a bottom isometric view of the rubber tread section of  FIG. 2 . 
         FIG. 4B  is a partial cutaway view of  FIG. 4A . 
         FIG. 5  is a cross-section view of a portion of  FIG. 1  detailing the tire retread apparatus against a shoulder of the tire. 
         FIG. 6A  is an isometric view of a tread splice in the tire retread apparatus. 
         FIG. 6B  is a partial cutaway of a portion of  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a tire  10  with a tire tread apparatus  12  shown generally as installed. A series of tread pads in the form of rubber blocks  14  separated from each other and arranged in a diagonal patchwork pattern are mechanically attached (e.g., cast) to a network of cables  16 . The rubber blocks  14  may be square or other shapes that lend to good traction. The rubber blocks  14  are positioned against the tread of a worn or carcass tire  10 . The cables  16  may be arranged at angles of 45 degrees from the equatorial plane  13  of the tire  10 , or may be at other convenient angles in relation to the equatorial plane  13 . The cables  16  pass through multiple of the rubber blocks  14 , entering and exiting each of the four sides of the blocks  14 . In this implementation, two cables enter or exit each side of the blocks  14 . 
     The cables  16  are further arranged between and mechanically attached (e.g., cast) to rubber shoulder pads  18  and  18 ′ placed against the shoulder of tire  10 . In this implementation, the shoulder pads  18 ,  18 ′ are formed as a sidewall strip  19  and an edge strip  21  formed generally at a perpendicular angle to the sidewall strip  19  and with triangular projections  23  with sides parallel to sides of adjacent rubber blocks  14 . The cables  16  enter the triangular projection  23  of the shoulder pads  18  and  18 ′ then bend at an angle near 90 degrees from entry to exit from the sidewall strip  19  along the sidewall of the tire  10 . The cables  16  then pass around an additional annular sidewall cable  20  and return outward where they enter the sidewall strip  19  and exit respective triangular projections  23  to cross the tread surface of the tire  10 , through the blocks  14 , and to the opposing edge rim  18 ,  18 ′. 
     The cable  20  may be composed of multiple segments in sequence, with ends of each segment attached within a tensioning fastener, for example, a tightening cylinder  22 . When each of the tightening cylinders  22  is tightened to an operational force, the entire circumference of the sidewall cable  20  may reach uniform and equal tensile force. In operation the rubber blocks  14  and rubber shoulder pads  18  and  18 ′ may act as replacement tread of the tire  10  and may be installed when the original tire  10  is sufficiently worn out. 
       FIG. 2  shows a typical tread pad in the form of a rubber block  14 . The rubber block  14  is generally a vulcanized rubber of similar composition to the tire  10 . Implementations are not limited to vulcanized rubber, however, and other tread compounds may constitute rubber block  14 . The top surface  24  is generally of square shape and this top surface  24  is what contacts the ground upon the rotation of tire  10 . However, as previously stated, the rubber block may be provided in any of a variety of tread shapes. In some implementations, there may be a variety of different shaped rubber blocks  14  in a particular tread design of the tire tread apparatus  12 . The rubber block  14  also has four sloping sides  26 , as shown. The dimensions of the rubber block  14  are not limited, but generally may be on the order of 10 in. by 10 in. square on the top surface  24 . The rubber block may have a thickness generally of 2-4 in. 
     The cables  16  shown in  FIG. 1  are relabeled for clarity in  FIG. 2  as cable pairs  28  and cable pairs  30 . The cable pairs  28  and  30  are cast within the rubber block  14 . The cable pairs  28  may cross the cable pairs  30  at right angles and may pass above or below in reference to each other within the rubber block  14 . The cable pairs  28  and  30  are not limited in size and type, but generally are a braided steel which may be ¼ in. diameter. The cable pairs  28  and  30  may not deform within the rubber block  14 . However, cable pairs  28  and  30  may, upon rotation of the tire  10 , collapse or deform in the interval between an adjacent rubber block  14 . This is particularly the case when the leading edge, trailing edge, and footprint of the tire  10  is in compression. 
       FIG. 3  is a detailed view of a spike  34  for holding the tread pads to the tire  10 . In some implications the length of the spike  34  may be generally 2-4 inches. The spike  34  shown may include a base  36 , a stem  38 , and a barb  40 . The barb  40  may be in the shape of a conical horn, with a sharpened point  42  and a circular rim  44 . The spike  34  is typically a metal such as steel, but may be made of other materials. The barb  40  may be of such a configuration that a cavity is defined between the circular rim  44  and the stem  38 . 
       FIG. 4A  is a perspective view of the rubber block  14  showing the bottom surface  32 . A plurality of the spikes  34  are shown exiting bottom surface  32 . In application, these spikes  34  may pierce and enter the original treads or carcass of the tire  10 , acting to attach the rubber block  14  securely. While  FIG. 4A  shows approximately twenty-five spikes  34 , there may be greater or fewer spikes  34  in other implementations. The spikes  34  may be formed with a flange as the base  36  around the stem  38  or other anchor structure at the end opposite the barb  40  in order to secure and embed the spikes  34  within the blocks  14  as shown in  FIG. 4B . 
     The spikes  34  may be insert molded during manufacture of the rubber blocks  14 . Before installation, the barb  40  may be coated with a lubricant to ease piercing into tire  10 . While tensioning the cables  20  during installation, and during initial use, the spikes  34  may pierce into the rubber carcass treads of tire  10  in a way to stretch and not cause excessive tears in the rubber or construction of tire  10 . The flanged base  36  is of sufficient diameter to securely maintain the spikes  34  rigidly in rubber block  14 . 
     The bottom surface  32  may be somewhat larger than the top surface  24 , which results in the sloped sidewalls  26 . The bottom surface  32  acts as a base of attachment of the rubber block  14  to the tire  10 . Heavy loads carried by excavating and haul equipment are transferred through the tire  10  to the rubber block  14  through this bottom surface  32 . 
       FIG. 5  is a cross-sectional view of rubber shoulder pads  18  and  18 ′. The cable  16  is shown entering and exiting shoulder pad  18  and passing over an internal steel cable  46  running circumferentially within the shoulder pads  18 ,  18 ′. The tire carcass  48  is shown in hatching in  FIG. 5 . The internal steel cable  46  is of somewhat larger diameter than the cables  16 . Under sufficient tightening of the tightening cylinders  22  and the resulting tension in the sidewall cable  20 , the cables  16  may develop a tensile force “y” as shown. The tensile force “y” may become uniform throughout all of cable segments  16  within each of multiple rubber blocks  14  and the spaces between rubber blocks  14 . Within rubber section  18  and  18 ′, the cables  16  bear directly against the internal steel shoulder cable  46  and may, under high tensile force, direct a force “b” against the shoulder cable  46  drawing the shoulder cable  46  in towards the shoulder  48  of the tire carcass  10 . The tensioning system of tightening cylinders  22 , sidewall cable  20 , cables  16 , and barbs  40 , acts to retain the rubber blocks  14  and rubber shoulder pads  18  and  18 ′ onto tire  10 . While the rubber tire  10  may deform and flex under movement with heavy loads, the multiple rubber blocks  14  and shoulder pads  18  and  18 ′ may remain statically positioned relative to and against the rubber tire  10 . 
     Each of tightening cylinders  22  shown, e.g., in  FIG. 1 , may be preset to an equivalent gripping pressure. The tightening cylinders  22  may be interconnected by supply line  50  to maintain a uniform fluid pressure among all tightening cylinders  22 . In practice, tightening cylinders  22  may be of hydraulic or pneumatic control. In pneumatic or air control, the internal air pressure of the tire, typically 100-120 psi, is drawn through the tire air valve  66 , and air hose  69 , and into a booster regulator  52  mounted to the rim  54  of the wheel. The booster regulator  52  may provide a 4× boost in air pressure to 400-500 psi. An exemplary booster regulator  52  may be a SMC Model NVBA1111-T02G-N. The high-pressure air then is maintained to the supply line  50  by distribution lines  65 , becoming available to each of tightening cylinders  22 . The distribution line  65  to the backside of the tire  10  may be routed through a hole in the rim  54  as shown in  FIG. 1 . The tightening cylinders  22  may be found in multiple configurations. One example is a FABCO-AIR “pancake cylinder” Model PSD, double-acting, single rod in 2½ in diameter, 3 in stroke. The tightening cylinders  22  may achieve a force in excess of 1,000 lbs, which is distributed throughout the cables  16 . 
     The booster regulator  52  may take the form of an independent hydraulic pump  52  as shown in  FIG. 1  mounted on the rim  54  of the tire  10 . Alternatively or in combination, a hydraulic or pneumatic system of the internal truck or equipment systems may be used. In another embodiment the tightening cylinders  22  may be replaced with spring systems or other tensioning systems. The tightening system may be found on both sides of the tire  10 . High tensile force in the cable  20  is maintained by fluid pressure applied to tightening cylinders  22 , which leads to uniform and equal tensile forces in cables  16 . It should be understood that air is considered a fluid in this disclosure. 
       FIG. 6A  is a detail of end attachment. During manufacture the tire tread apparatus  12  may be molded as one completed interconnected assembly with a first end and second end, as shown. A number of tie plates  56  may be insert molded within rubber blocks  14  and also insert molded within rubber sections  18  and  18 ′, as shown. Referring to  FIG. 6A , the tie plates  56  also contain hollow eyelets  58  in which cables  16  are securely attached, for example, with the use of crimp clips  60 . The hollow eyelets  58  are threaded with a tie cable  62  as shown. During installation, the tire tread apparatus  12  may be shrouded or covered over the worn tire  10  and tightened with the tie cable  62 . After tightening with the tie cable  62 , the tightening cylinders  22  are set to pressure causing a uniform and continuous tensioning of the entire system of cables  16 . 
     All directional references (e.g., proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, and counterclockwise) are only used for identification purposes to aid the reader&#39;s understanding of the present invention, and do not create limitations, particularly as to the position, orientation, or use of the invention. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and may include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to each other. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto may vary. 
     The above specification, examples and data provide a complete description of the structure and use of exemplary embodiments of the invention. Although various embodiments of the invention have been described above with a certain degree of particularity, or with reference to one or more individual embodiments, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of this invention. In particular, it should be understood that the described technology may be employed independent of a personal computer. Other embodiments are therefore contemplated. It is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative only of particular embodiments and not limiting. Changes in detail or structure may be made without departing from the basic elements of the invention as defined in the following claims.