Patent Publication Number: US-2023159119-A1

Title: Rubber Track for a Tracked Vehicle, and Tracked Vehicle Comprising Said Rubber Track

Description:
BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     The present invention relates to a rubber track for a tracked vehicle according to the preamble of claim  1 ; furthermore, the present invention relates to a tracked vehicle comprising said rubber track. 
     2. The Relevant Technology 
     As is known, the category of tracked vehicles includes many vehicles differing from one another in both shape and function, ranging from military vehicles, conceived for particular requirements of mobility on rough terrain (tanks, self-moving artillery pieces, vehicles for troop transportation) to civil vehicles for work activities or special applications. The adoption of tracks in the place of wheels, in fact, permits the tracked vehicle to distribute its own weight over a larger surface, thus limiting the sinking in the ground, and allows it to overcome steep slopes and run on very rough terrain. Therefore, tracked vehicles are especially suited for use on soft, muddy, sandy, snowy, etc. terrain. 
     In this frame, the tracked vehicles known in the art comprise a pair of tracks, wherein each track consists of a closed-loop structure and is laterally associated with the vehicle with reference to the direction of forward motion of the vehicle. 
     Each track is generally driven by a drive wheel and tensioned by at least one idler wheel, which is usually longitudinally slidable for adjusting the track tension. 
     Each track can be kept in adherence to the ground by means of one or more intermediate idle support wheels, which make it possible to distribute the weight of the tractor evenly on the ground, while optional support rollers guide and support the upper part of the track. 
     The assembly made up of the drive wheel, the idler wheel, the support wheels and the support rollers is the so-called “track carriage”. 
     The operation of tracked vehicles can be summarized as follows: the drive wheel receives, via the transmission, the motive force of the engine with the necessary torque and the desired speed; in its turn, it rotates the track with which it is engaged, thereby also dragging the idler wheel, which keeps the track under tension. Since tracked vehicles cannot be steered like wheel-equipped vehicles, the steering of tracked vehicles is effected by causing the two tracks to move forward or backward at different speeds; this is obtained by operating manipulators (joysticks), through which the drive engines are made to receive a variable oil flow from the hydraulic distributor. 
     In particular, closed-loop tracks are known in the art which are essentially composed of mutually hinged metallic elements; however, such metallic tracks suffer from the drawback that they are rather slow and noisy when the tracked vehicle is moving, in addition to causing considerable damage to the roads and surfaces whereon the vehicle runs. 
     Metallic closed-loop tracks are also known in the art which are provided with rubber layers covering, and usually fixed (e.g., bolted) to, the metallic tracks; however, this solution has several drawbacks as well, such as higher costs and more labour necessary for repairs, in that tracks thus designed are often subject to detachment and/or breakage of the rubber layers, which therefore need frequent replacement. 
     In order to overcome the above-mentioned drawbacks of metallic closed-loop tracks, rubber tracks have been developed over the years, which have had great success because they are much faster and considerably less noisy than metallic ones; moreover, rubber tracks do not damage the roads and surfaces whereon the vehicle runs, and can therefore be driven also on normal roads. 
     However, direct contact between the rubber and the ground inevitably results in track damage, so that the life cycle of a rubber track is clearly shorter than that of a metallic track. 
     In this frame, European patent No. EP1238898B1 relates to a tracked vehicle comprising a pair of endless closed-loop tracks made of rubber, wherein each track is adapted to be mounted on first and second toothed wheels and to be made to rotate between said wheels by driving at least one of said toothed wheels. 
     In particular, the track shown in European patent No. EP1238898B1 comprises:
         a plurality of inner shoes and a plurality of outer shoes made of metallic material, wherein each inner shoe lies opposite to a respective outer shoe;   an endless ring-shaped support element retained between said inner shoes and said outer shoes, said rubber element incorporating an endless ring-shaped element made of metal, so that it extends along a longitudinal direction of the rubber element.       

     According to the teachings contained in European patent No. EP1238898B1, said inner shoes are arranged side by side along the inner surface of the support element, and said outer shoes are arranged side by side along the outer surface of the support element, wherein:
         each inner shoe is at least partly buried in the rubber track, so that a portion coupled to the toothed wheel and a portion connected to the outer shoe are left exposed;   screws or bolts are used for connecting each inner shoe to each respective outer shoe, wherein said screws or bolts extend within threaded apertures or holes formed in each inner shoe and each outer shoe, said threaded apertures or holes being so oriented as to allow each inner shoe to be connected to the respective outer shoe.       

     However, even the rubber track described in document EP1238898B1 has some drawbacks, which are mostly due to the fact that in such a rubber track the coupling between each inner shoe and the respective outer shoe is achieved only by means of said screws or bolts, such elements being thus subject to mechanical forces that are exclusively transmitted thereto while the track is moving; it is therefore clear that such mechanical stresses jeopardize the life and the tightening action of the screws or bolts that connect each inner insert to the respective outer insert. 
     Also with this solution, therefore, the tracks require much labour for the necessary repairs, in that tracks thus designed are often subject to deformation and breakage of the inner and outer shoes (or inserts), requiring replacement thereof (or of the entire track). 
     Another drawback of the solution shown in document EP1238898B1 is due to the fact that the inner and outer shoes are arranged side by side along the inner periphery and the outer periphery, respectively, of the rubber element; as a consequence, such provisions may cause significant interference between the side-by-side inserts or shoes as the track winds around the drive wheel. 
     SUMMARY OF THE INVENTION 
     In this frame, it is the main object of the present invention to provide a rubber track for a tracked vehicle, and an associated tracked vehicle, so realized as to overcome the drawbacks of the prior art. 
     In particular, it is one object of the present invention to provide a rubber track, and an associated tracked vehicle, so realized as to properly distribute the mechanical forces generated during the motion of the track. 
     Consequently, it is one object of the present invention to provide a rubber track, and an associated tracked vehicle, which are so realized as to increase the life and integrity of the inner and outer shoes associated with the rubber track, and also of the rubber track itself, thus considerably extending the time intervals to be observed for maintaining or replacing such components. 
     It is a further object of the present invention to provide a rubber track, and an associated tracked vehicle, which are so realized as to be able to operate properly on different surfaces, particularly also on very rough terrain (e.g., soft, muddy, sandy, snowy, etc. terrain) and/or steep slopes. 
     It is another object of the present invention to provide a rubber track, and an associated tracked vehicle, which are so conceived as to avoid any undesired interference of the inner and outer inserts as the track winds around the drive wheel and the idler wheel. 
     It is yet another object of the present invention to provide a rubber track, and an associated tracked vehicle, which are so realized as to avoid any irregularity in the forward motion of the vehicle, particularly by avoiding the generation of constant-frequency vibrations that might adversely affect the whole superstructure of the vehicle, resulting in annoying noise and poor driving comfort. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects, features and advantages of the present invention will become apparent from the following detailed description and from the annexed drawings, which are supplied by way of non-limiting explanatory example, wherein: 
         FIG.  1 A  and  FIG.  1 B  are perspective views of, respectively, a tracked vehicle and a rubber track according to the present invention; 
         FIG.  2 A  and  FIG.  2 B  are, respectively, an exploded perspective view and a side sectional view of a portion of the rubber track according to the present invention; 
         FIG.  3 A  and  FIG.  3 B  are, respectively, a perspective view of a portion of the outer surface of the track and a side sectional view of the track portion shown in  FIG.  3 A ; 
         FIG.  4 A  and  FIG.  4 B  are, respectively, a perspective view of a portion of the inner surface of the track and a plan view of the track portion shown in  FIG.  4 A . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the annexed drawings, in  FIG.  1 A  reference numeral  1  designates as a whole a tracked vehicle according to the present invention. 
     The vehicle  1  is provided with a body  2  comprising a drive cabin  3 , an engine (not shown in  FIG.  1 A , since it is preferably inserted in a suitable housing formed in the body  2 ), and a pair of track carriages  4  arranged on the right side and the left side of the body  2 . 
     In the embodiment shown in  FIG.  1 A , the vehicle is a tracked skid loader, which comprises at least one arm  5  associated with the body  2  in such a way that it can move vertically up and down, wherein said at least one arm  5  is equipped, at its end, with a bucket  6 , which in turn is constrained to the arm  5  in such a way that it can rotate up and down. Such tracked skid loader may then be equipped with an attachment coupler (not shown), in particular of the hydraulic type and, preferably, associated with said at least one arm  5 , which permits the connection and operation of external attachments. 
     Each track carriage  4  is provided with a rubber track  10  according to the present invention, wherein said track  10  is driven by at least one drive wheel (not shown in detail in  FIG.  1 A ); in addition, the track  10  is preferably kept under tension by at least one idler wheel (also not shown in detail in  FIG.  1 A ). 
     It should be noted that the vehicle  1  according to the present invention may also consist of a vehicle other than the above-described tracked skid loader; merely by way of example, the vehicle  1  according to the present invention may be a mini excavator, in particular of the 1 to 15 ton type. 
     It should also be noted that, for the purposes of the present invention, the term “rubber” is used to indicate any material characterized by high elasticity and deformability, wherein such material may be of natural origin (like materials obtained by coagulation of the latex of some plants, such as natural rubber or caoutchouc) or artificial origin (like those obtained by hot or cold polymerization of olefinic hydrocarbons and derivatives thereof in the presence of catalysts, as is the case, for example, of synthetic rubber); it is therefore evident that the term “rubber” should not be understood in a limiting sense. 
       FIG.  1 B  shows a perspective view of a rubber track  10  according to the present invention. 
     In particular, in such  FIG.  1 B  one can see that the track  10  is of the endless, closed-loop type, and is suitable for installation on first and second wheels of the vehicle  1  to be rotatably driven between said wheels by the motion of at least one of said wheels, in particular a toothed drive wheel. 
     Moreover, when observing  FIGS.  1 B to  2 B  it can be noticed that the track  10  comprises a plurality of inner shoes  11  and a plurality of outer shoes  12 , wherein each inner shoe  11  lies opposite to a respective outer shoe  12 . 
     The inner shoe  11  has a substantially arched shape and is provided with a first intermediate portion  11 I and first ends  11 E, while the outer shoe  12  is provided with a second intermediate portion  12 I and second ends  12 E, said first ends  11 E and second ends  12 E being substantially parallel to each other and forming a first contact surface between the inner shoe  11  and the outer shoe  12 . 
     In addition, the track  10  comprises a support element  13  made of rubber and shaped as an endless ring retained between said inner shoes  11  and said outer shoes  12 . 
     It must be pointed out that said first contact surface formed by the first ends  11 E and second ends  12 E may also be realized by interposition of a rubber portion, in particular a rubber portion belonging to the support element  13 . 
     The inner shoes  11  are arranged mutually spaced apart along the inner surface of the support element  13  and the outer shoes  12  are arranged spaced apart along the outer surface of the support element  13 , wherein the first intermediate portion  11 I of each inner shoe  11  is at least partly buried in the support element  13  (as is especially visible in  FIG.  2 A , in which the support element  13  has been drawn with dashed lines in order to highlight the inner shoe  11 ). 
     In substance, the inner shoes  11  and the outer shoes  12  are arranged transversally relative to a longitudinal development (designated by the double arrow SL in  FIG.  1 B ) of said support element  13  and of the track  10  itself. 
     The fact that the inner shoes  11  are mutually spaced apart along the inner surface of the support element  13  and the outer shoes  12  are mutually spaced apart along the outer surface of the support element  13  makes it possible to prevent any undesired interference between such components as the track  10  winds around the wheels of the vehicle  1 . 
     Preferably, said support element  13  comprises, buried therein, at least one metallic element shaped as an endless ring (not shown in the drawings), which extends along the longitudinal development SL of the track  10 , in particular said element being made from steel strands wound into multiple seamless coils. Such a solution ensures higher tear resistance and prevents the track  10  from elongating; this avoids the need for an operator to make continual adjustments of the tension of the metallic element buried in the track, as is the case with prior-art tracks. 
     The track  10  according to the present invention comprises a plurality of connection elements  14  for creating the junction between each inner shoe  11  and the respective outer shoe  12 , wherein said connection elements  14  are held inside first seats  11 S formed in the first ends  11 E of each inner shoe  11  and inside second seats  12 S formed in the second ends  12 E of each outer shoe  12 . 
     In particular, a pair of connection elements  14  are used for each one of the ends  11 E,  12 E of said inner shoes  11  and outer shoes  12 ; in fact,  FIG.  2 A  shows that two connection elements  14  are used for one of the ends  11 E,  12 E of the inner shoes  11  and outer shoes  12 , and two other connection elements  14  are used for the other end  11 E,  12 E of said inner shoes  11  and outer shoes  12 . 
     It is however clear that a different number of connection elements  14  may be used than shown in  FIG.  2 A . 
     In accordance with a preferred embodiment, said connection elements  14  consist of square underhead bolts; said bolts are preferably inserted from the inner surface of the track  10  towards the outer surface of said track  10 , in particular a head  14 A of said bolts being retained in a first seat  11 S of the inner shoe  11 , which is shaped to receive said head  14 A without allowing it to turn. 
     This embodiment makes it possible to work from the outer surface of the track  10  only, in particular by using a screwer on a nut  14 B of the bolt, thus not requiring the track  10  to be removed from the vehicle  1  for periodically checking the tightening torque of the connection elements  14  or for replacing one or more outer shoes  12 . 
     In accordance with the present invention, the first intermediate portion  11 I of the inner shoe  11  and the second intermediate portion  12 I of the outer shoe  12  comprise mutual coupling elements  20  (designated as a whole by reference numeral  20  in  FIGS.  2 A and  2 B ) forming a second contact surface between said inner shoe  11  and outer shoe  12 . 
     In this respect, it is evident that said coupling elements  20  are formed on the mutually facing surfaces of the first intermediate portion  11 I and second intermediate portion  12 I. 
     In a preferred embodiment, said coupling elements  20  comprise a male element  21 M adapted to be received inside a female element  21 F so as to create a coupling system, in particular a joint, of the male/female type. 
     In the preferred embodiment shown in  FIGS.  2 A and  2 B , the male element  21 M is formed on the second intermediate portion  12 I of the outer shoe  12  and the female element  21 F is formed on the first intermediate portion  11 I of the inner shoe  11 ; it is however clear that such elements may be inverted, i.e., the male element  21 M may be formed on the first intermediate portion  11 I of the inner shoe  11  and the female element  21 F may be formed on the second intermediate portion  12 I of the outer shoe  12 . 
     Such provisions permit making the inner shoe  11  and the outer shoe  12  more resistant to the drive torque generated by the transmission of the vehicle  1  as it accelerates. 
     Consequently, the provisions of the present invention make it possible to provide a track  10 , and an associated tracked vehicle  1 , which are so realized as to correctly distribute the mechanical forces generated when the track  10  is moving; it is therefore clear that such provisions ensure a longer life and a higher integrity of the inner shoes  11  and outer shoes  12  associated with the track  10 , as well as of the rubber track  10  itself, thus considerably extending the time intervals to be observed for servicing such components. 
     In accordance with a preferred embodiment, the inner shoe  11  is made of metallic material. 
     In such preferred embodiment, the outer shoe  12  is also made of metallic material; however, said outer shoe  12  may be made of different materials. 
     In  FIGS.  3 A and  3 B  one can notice that the outer shoe  12  may be so realized as to comprise indentations  15  rising from the outer shoe  12  in the direction opposite to the respective inner shoe  11 . 
     In particular, the indentations  15  may be so realized as to have different shapes and/or heights relative to the support element  13 , depending on the field of application where the vehicle  1  of the present invention will have to be used. 
     In fact, in  FIGS.  3 A and  3 B  one can notice that the outer shoe  12  may be so realized as to have no indentations  15  (as is the case in the embodiment designated by letter A), or to have indentations  15  having a first shape and a first height relative to the support element  13  (as is the case in the embodiment designated by letter B), or to have indentations  15  having a second shape and a second height relative to the support element  13  (as is the case in the embodiment designated by letter C). 
     Alternatively, the outer shoe  12  may be so realized as to have a core made of metallic material at least partly coated with rubber (as in the case in the embodiment designated by letter D), or said outer shoe  12  may be substantially totally made of rubber. 
     It must be pointed out that the outer shoes  12  to be sequentially associated with the support element  13  should preferably be all realized as shown in any one of the embodiments designated by letters A to D in  FIGS.  3 A and  3 B , and that it will seldom be feasible to simultaneously use different outer shoes  12  from different embodiments. 
     It is evident that the above-described possible embodiments of the outer shoe  12  permit obtaining a track  10 , and an associated vehicle  1 , which is of a modular type, in that it is suitable for adequately operating on different surfaces, and especially on very rough terrain (e.g. soft, muddy, sandy, snowy, etc. terrain) and/or steep slopes; in this regard, in fact, it should be noted that it will be sufficient to provide the track  10  with an outer shoe  12  specifically designed for a particular application (asphalt, building yard, forestry, snow removal, and so forth) and/or for a particular terrain and/or for a given slope where the vehicle  1  of the present invention will have to be used. 
     The inner surface of the track  10  comprises a plurality of teeth  16  coupled two by two transversally to the longitudinal development SL of the track  10 , so as to form pairs of teeth  16  spaced apart along the longitudinal development SL of the track  10 , which define a substantially U-shaped seat; in this embodiment, the pairs of teeth  16  act as a guide for the wheels of the vehicle  1 . 
     In  FIGS.  4 A and  4 B  it can be noticed that the inner surface of the track  10  comprises a plurality of first knobs  17 A and a plurality of second knobs  17 B projecting vertically from the support element  13 , wherein the first knobs  17 A are mutually aligned and spaced apart along the longitudinal development SL of the track  10  and the second knobs  17 B are mutually aligned and spaced apart along said longitudinal development SL; in this respect, the first knobs  17 A and the second knobs  17 B form a rigid support surface for the wheels (and/or any rollers) that carry the weight of the vehicle  1 . 
     In accordance with a preferred embodiment, as is particularly visible in  FIG.  4 B , each first knob  17 A is longitudinally offset (with reference to the longitudinal development SL of the track  10 ) relative to each second knob  17 B. 
     In substance, each second knob  17 B is at least partly positioned alongside a respective first space  18 A interposed between a pair of aligned and spaced apart first knobs  17 A, and each first knob  17 A is at least partly positioned alongside a respective second space  18 B interposed between a pair of aligned and spaced apart second knobs  17 B. 
     It should be noted that the first knobs  17 A and the second knobs  17 B are external to the teeth  16 , i.e., closer to the outer edges of the support element  13 . 
     The provisions concerning the first knobs  17 A and the second knobs  17 B permit realizing the track  10  according to the present invention in such a way as to avoid any irregularity in the forward motion of the vehicle  1 , particularly by avoiding the generation of constant-frequency vibrations that might adversely affect the whole superstructure of the vehicle  1 , resulting in annoying noise and poor driving comfort. 
     The features of the track  10  and of the associated vehicle  1  according to the present invention, as well as the advantages thereof, are apparent from the above description. 
     In particular, the peculiar features of the present invention make it possible to realize the track  10 , and the associated vehicle  1 , in such a way as to correctly distribute the mechanical forces generated when the track is in motion and to ensure a longer life and a higher integrity of the inner shoes  11  and outer shoes  12  associated with the track  10 , as well as of the track  10  itself, thus considerably extending the time intervals to be observed for servicing such components. 
     Furthermore, the track  10  according to the present invention is so realized as to be able to properly operate on different surfaces, and particularly also on very rough terrain (e.g. soft, muddy, sandy, snowy, etc. terrain) and/or steep slopes; in this regard, in fact, it should be noted that it will be sufficient to provide the track  10  with an outer shoe  12  specifically designed for a particular application (asphalt, building yard, forestry, snow removal, and so forth) and/or a particular terrain and/or a given slope where the vehicle  1  of the present invention will have to be used. 
     The track  10  according to the present invention is then so realized as to avoid any irregularity in the forward motion of the vehicle  1 , particularly by avoiding the generation of constant-frequency vibrations that might adversely affect the whole superstructure of the vehicle  1 , resulting in annoying noise and poor driving comfort. 
     The track  10  and the associated vehicle  1  described herein by way of example may be subject to many possible variations without departing from the novelty spirit of the inventive idea; it is also clear that in the practical implementation of the invention the illustrated details may have different shapes or be replaced with other technically equivalent elements. 
     It can therefore be easily understood that the present invention is not limited to the above-described track  10  and associated vehicle  1 , but may be subject to many modifications, improvements or replacements of equivalent parts and elements without departing from the inventive idea, as clearly specified in the following claims.