Abstract:
A tracked vehicle including a chassis, a drive train coupled to the chassis, and at least one track driven by the drive train. The at least one track having a plurality of stamped metal links each being pivotally coupled to corresponding adjacent metal links, and an elastomeric member coupled to all of the plurality of stamped metal links. The elastomeric member covers most of each of the stamped metal links.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to track systems for tracked vehicles, and, more particularly, to a rubber track having metal internal links. 
         [0003]    2. Description of the Related Art 
         [0004]    Farmers utilize a wide variety of vehicles and implements, among them are vehicle having tracked drive systems. A tracked drive is a system of vehicle propulsion in which a continuous band of treads is driven by two or more wheels. This band is typically made of modular steel plates, in the case of military vehicles and construction equipment, or rubber reinforced with steel wires in the case of agricultural or lighter construction vehicles. The large surface area of the track distributes the weight of the vehicle better than wheels on an equivalent vehicle, enabling a continuous tracked vehicle to traverse soft ground with superior traction and less likelihood of becoming stuck. An advantage of the use of metal plates is that they are both hard-wearing and damage resistant, especially in comparison to rubber tires. The aggressive nature of the track provides good traction in soft surfaces, but can damage paved surfaces. Special tracks can be configured to allow the installation of rubber pads on the treads for use on paved surfaces to prevent the damage. 
         [0005]    Tracks are typically built from modular links, which are linked together to form a closed chain. The links are joined by a hinge like pivotal coupling, which allows the track to be flexible and wrap around a set of wheels to make an endless loop. The links are typically broad, and made of a manganese alloy steel for high strength, hardness, and abrasion resistance. 
         [0006]    Generally, track construction and assembly are dictated by the application. For military vehicles often a track shoe that is integral to the structure is used in order to reduce track weight. In contrast, agricultural and construction vehicles often use a track with shoes that attach to the chain with bolts and do not form part of the chain&#39;s structure. This allows track shoes to break without compromising the ability of the vehicle to move and decrease productivity but increases the overall weight of the track and vehicle. 
         [0007]    There can exist some general disadvantages of tracks, which may include a lower top speed, much greater mechanical complexity, shorter life and damage that the all-steel versions cause to what they travel over. In an urban environment vehicle laws and local ordinances often require rubberized tracks or track pads be used on tracked vehicles. A compromise between all-steel and all-rubber tracks exists: attaching rubber pads to individual track links to ensure that the tracked vehicles can travel more smoothly, quickly, and quietly on paved surfaces. While these pads may reduce a vehicle&#39;s traction, they reduce damage to pavement. 
         [0008]    Many vehicle manufacturers provide rubber tracks instead of steel, especially for agricultural applications. Rather than a track made of linked steel plates, a reinforced rubber belt with chevron treads is used. In comparison to steel tracks, rubber tracks are lighter, make less noise, create less maximal ground pressure and do not damage paved roads. The disadvantage is that they are not as solid as steel tracks. 
         [0009]    Generally rubber tracks are formed around a basic carcass or belt. The carcass includes an endless belt-shaped rubber-like elastic member, a number of core bars, which can be made of metal, can be embedded therein and aligned and extend in traverse direction of the track. Steel cords, which serve as tension-resistant members may be embedded in the endless elastic member to surround the core bars. 
         [0010]    A concern about the expense of a metal linked track is the cost of the castings or forgings needed to build each link. Concerns about rubber tracks are the durability and traction. 
         [0011]    What is needed in the art is a track system that has less expensive metal links and improved traction. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention provides a hybrid metal/rubber track. 
         [0013]    The invention in one form is directed to a tracked vehicle including a chassis, a drive train coupled to the chassis, and at least one track driven by the drive train. The at least one track having a plurality of stamped metal links each being pivotally coupled to corresponding adjacent metal links, and an elastomeric member coupled to all of the plurality of stamped metal links. The elastomeric member covers most of each of the stamped metal links. 
         [0014]    The invention in another form is directed to a track for a tracked vehicle having a drive train. The track includes a plurality of stamped metal links each being pivotally coupled to corresponding adjacent metal links, and an elastomeric member coupled to all of the stamped metal links. The elastomeric member covering most of each of the stamped metal links. 
         [0015]    The invention in yet another form is directed to a method of making a track for a tracked vehicle. The method includes the steps of: stamping and forming a plurality of metal links; pivotally coupling each of the metal links to two corresponding adjacent metal links; and coupling an elastomeric member to all of the stamped metal links. The elastomeric member covering most of each of the stamped metal links. 
         [0016]    An advantage of the present invention is that metal cleats extend into the ground for superior traction. 
         [0017]    Another advantage is that the cleats are inexpensively formed using a stamping process. 
         [0018]    Yet another advantage is the drive of the vehicle interfaces with metal pins that are exposed on the inside of the track. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein: 
           [0020]      FIG. 1  is a perspective view of an agricultural vehicle in the form of a tractor having an embodiment of a ground contacting track of the present invention coupled to a drive train of the tractor; 
           [0021]      FIG. 2  is a view of a piece of strip steel from which stamped metal links of the present invention are made for use in the track of  FIG. 1 ; 
           [0022]      FIG. 3  is a schematical side view of a step in the forming process through which each stamped metal link previously processed in  FIG. 2  is formed for use in the track of  FIG. 1 ; 
           [0023]      FIG. 4  is a schematical side view of another step in the forming process through which each stamped metal link previously processed in  FIGS. 2 and 3  is formed for use in the track of  FIG. 1 ; 
           [0024]      FIG. 5  is a schematical side view of another step in the forming process through which each stamped metal link previously processed in  FIGS. 2-4  is formed for use in the track of  FIG. 1 ; 
           [0025]      FIG. 6  is a schematical side view of another step in the forming process through which each stamped metal link previously processed in  FIGS. 2-5  is formed for use in the track of  FIG. 1 ; 
           [0026]      FIG. 7  is a side view of a stamped metal link processed by the steps portrayed in  FIGS. 2-6  is formed for use in the track of  FIG. 1 ; 
           [0027]      FIG. 8  is a top view of a series of the metal links of the present invention that are pivotally coupled together; and 
           [0028]      FIG. 9  is a side sectional view taken along A-A of  FIG. 8  as fully assembled with a rubber member. 
       
    
    
       [0029]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0030]    Referring now to the drawings, and more particularly to  FIG. 1 , there is shown an embodiment of a rubberized track system  10  in use by a tractor  12 . Tractor  12  has a drive train  14  that includes a drive sprocket  16 , which drives track  10 . 
         [0031]    Now, additionally referring to  FIG. 2  there is shown a piece of strip steel  18  from which clamp plates  20  and stamped link forms  22  are made illustrated here in schematic form as parts of strip steel  18 . It is possible that clamp plates  20  and stamped link forms  22  may be sized to significantly utilize most of strip steel  18  to thereby efficiently form the components with minimal scrap. 
         [0032]    Now, additionally referring to  FIGS. 3-7  there is shown die sets  24 ,  26 ,  28  and  30 , which are used to progressively bend stamped link form  22  into a stamped metal link  32 . Studs  34  may be welded to a surface of stamped metal link  32  or studs  34  may extend through a hole in stamped metal link  32 , and then be welded thereto. A weld  36  is applied along the ends of the formed metal to hold stamped metal link  32  together as an integral unit. 
         [0033]    Now, additionally referring to  FIG. 8 , pins  38  are inserted in the corresponding openings of adjacent stamped metal links  32 , which have cleats  40  extending outwardly, to form a track chain  42 . Pins  38  may additionally have bushings associated therewith and even means to lubricate pins  38  to facilitate the pivotal coupling between pins  38  and stamped metal links  32 . Stamped metal links  32  have a Z-shape or a stretched Z-shape, as can be seen in  FIG. 8 . 
         [0034]    Now, additionally referring to  FIG. 9 , there is shown a cross-sectional view of a portion of track chain  42  in the finished rubberized track system  10 , showing an elastomeric member  44 , which may be referred to as a rubber member  44  that largely surrounds each stamped metal link  32 , and the ends of pins  38 . Cleat  40  extends through an outer surface of elastomeric member  44  and clamp plate  20  is placed around cleat  40  on the surface of elastomeric member  44  and studs  34  are riveted down upon clamp plate  20 . Elastomeric member  44  covers over half of each stamped metal link  32 , and can be thought of as mostly covering each of the stamped metal links  32  in track chain  42 . 
         [0035]    On the underside of rubberized track system  10 , the middle portion of pins  38  is left exposed so that cogs of sprocket  16  can directly engage pins  38  to drive track system  10 . The exposure of cleats  40  improve the traction of track system  10  over an all rubber track since cleat  40  readily engages the ground. 
         [0036]    To summarize the inventive track  10  that can be used with a dozer crawler is made from rubber  44  over molded on links  32  with steel cleats  40  for traction and pinned connections  38 . This allows for a “light” dozer track, but with steel cleats protruding. The general construction is vulcanized rubber  44  over-molded onto a chain  42  made of linked steel cleats  32 , while also providing drive pins  38  in s form that allows direct interaction with sprocket  16 . It is a preferred embodiment for the steel cleats/links to be made by using a production stamping method. Using recently developed steel that is mild enough to be formed by bending, but has sufficient chemistry to be heat treatable and hardened, such as steel discussed in US Patent application Publication No. 2013/0186526. 
         [0037]    While conventional all metal tracks are made from a series of links pinned together to form a continuous track. The shoes are bolted to the links to form a continuous face. Presented to the ground, the face provides traction via cleats protruding from each shoe and flotation via the flat portion of each shoe. The traditional type track is heavy, complicated, and labor intensive to assemble. In addition, the links must be precision machined to form the pin holes. In addition, the pins must be precision machined to properly fit into the holes in the links. All this adds up to a very expensive track assembly. 
         [0038]    The present invention solves these issues by providing the same durability and performance of an all metal track with rubber tracks. The rubber tracks  10  are less expensive, less complicated, and less noisy than conventional tracks. 
         [0039]    The construction is a series of metal links  32  pinned together. At the top level of assembly, the track  10  is made when the chain  42  of pined links  32  is positioned inside a rubber vulcanizing mold. The mold is loaded with rubber in the raw vulcanized state, and then the mold is clamped shut and heated. The rubber is vulcanized onto, or over-molded with the chain of links  42 . The production mold and links are formed in such a way as to leave the center portion of each chain pin  38  exposed. This portion of pin  38  will be used to engage with the drive sprocket  16 . Also the top portion  40  of each link  32  is left exposed. This portion of link  32  is used to engage the ground and provide a superior level of traction than could be achieved with rubber only. The links  32  will be formed in manufacturing using the stamping process, while the prior art track shoes are formed using the forging, extruding, or casting process. The stamping process used for the present invention is less expensive than any of the current methods of manufacturing and lends itself to high volume production. 
         [0040]    The use of the formable, yet treatable steel makes the track shoe  32  hard and abrasive resistant enough to maintain its form after hundreds even thousands of hours of engaging soil, gravel, and rocks under high loads. 
         [0041]    The entire track  10  is molded complete and all at once in a way similar to how an agricultural tractor track is molded. However, the present invention disclosed herein is over molded on a belt of metal links  32  that are pinned together to form a continuous band. This adds strength in tension, resistance against stretching, and provides lateral stiffness across the full width of track. Lateral stiffness helps to evenly distribute the weight of the equipment/load over a wide area. The larger “foot Print” provides flotation and decreases compaction of the ground beneath. The track pins  38  are exposed in the center area of the track. The exposed portion of the track pins are engaged by the cogged drive sprocket  16 . The cogs of the drive sprocket  16  engage the track pins  38  and transfer torque and power to the track  10 . The use of a cogged drive sprocket  16  is the conventional way a tracked vehicle is driven, and is advantageously used by the present invention. 
         [0042]    The internal links  32  are designed in such a way as to be made using the high production stamping process. Employing either a progressive or transfer type production die. The links  32  of the track “Chain” are formed in such a way as to present a strip of steel, which protrudes out of the rubber portion of the track assembly, and therefore provide high traction with the ground. The links  32  are also formed in such a way as to form a hole for the pivot pins  38  to engage and be fixed in. Rubber tracks have been used in smaller tracked construction equipment for many years. The links  32  are formed in such a way as to be pinned together continuously. In addition to providing a pivoting connection between all the links, the pins  38  provide a strong location for the drive sprocket to engage and transfer torque to the track  10 . 
         [0043]    In addition the links  32  are formed in such a way as to protrude above the main portion of the rubber track  10 . The protrusion  40  taking the shape of a strip running laterally across the width of the track  10 . The height to which this strip of steel  40  protrudes above the height of the main body of the track  10  being determined by the shape of the formed link  32 . Thereby, the depth of the steel link protrusion  40  as it engages with the ground is controllable. Different levels of aggression can be produced, and offered for usage. This is the feature that elevates this track above conventional tracks in use today. The feature being a strip of steel protruding from the main body of the track to engage the ground and provide powerful traction when required for soil and gravel pushing operations. 
         [0044]    Also described here is a preferred way to form the rubber adjacent to the protruding steel portion of the link to discourage delamination of rubber from steel. This way keeping the rubber bonded to the steel link. In addition, the invention described herein includes a mechanical way of bonding rubber to steel links to provide a robust lock between the two members. In the customary way a chemical “paint” is applied to the steel links prior to being inserted in the mold to provide a chemical bond between the rubber and steel components. 
         [0045]    This track  10  allows for designs that work with existing dozers requiring no modification. The method of forming the holes to engage pivot pins in the links is not machined but formed in the stamping operation by bending the metal around a tooling mandrel. This is a cost reduction. The link  32  comes out of the stamping operation complete and ready for the heat treat/hardening process. 
         [0046]    Advantages of the present invention include: Quiet operation as compared to an all metal track. Reduction of track generated noise. A strong commercial advantage if the industry continues using rubber track on larger vehicles. The use of stamped steel cleats could be used on any size vehicle that requiring increased traction. Cheaper to produce. A good alternative for a customer looking for something less costly. 
         [0047]    In addition, the rubber  44  can be prevented from delaminating from the steel link  32  by way of clamp plate  20 . The clamp plate  20  is riveted to welded studs  34  that are welded to the links  32  after forming. 
         [0048]    While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.