Patent Publication Number: US-2018037280-A1

Title: Track shoe

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to track vehicles, and in particular to a track shoe. 
     BACKGROUND 
     Track vehicles, for example, large hydraulic excavators, generally include a drive unit having a drive sprocket and one or more idlers or rollers for guiding the track. The track includes a plurality of track links, generally referred to as shoes, connected to each other by pins. These shoes support the weight of the associated machine as the machine travels on the ground. 
     DE 10 2011 012 711 B3 discloses an example of a crawler drive including a drive sprocket, an idler, a plurality of rollers, a plurality of belt-tighteners and an endless track formed by a plurality of pivotally connected track shoes. 
     The present systems and methods are directed at least in part to improving known systems. 
     SUMMARY OF THE DISCLOSURE 
     In one aspect, the present disclosure relates to a track shoe for a track, in particular, a track of a large hydraulic excavator, comprising a plate-shaped base having a substantially rectangular base surface and being defined in a circumferential direction by a left side surface, a right side surface, a front surface, and a rear surface. A first connecting portion is disposed on the base and protrudes from the front surface. A second connecting portion is disposed on the base and protrudes from the rear surface. The second connecting portion is configured for connecting to the first connecting portion of another identically formed track shoe such that it is rotatable with respect to the track shoe about an axis of rotation. The front surface and the rear surface comprise a front stopper and a rear stopper, respectively, configured such that, upon rotation, the rear stopper of the track shoe abuts against the front stopper of the other track shoe to limit the rotation to a predetermined angle. 
     In another aspect, the present disclosure relates to a track shoe for a track, in particular, a track of a large hydraulic excavator, comprising a plate-shaped base having a substantially rectangular base surface and being defined in a transverse direction by a left side surface and a right side surface and in a longitudinal direction by a front surface and a rear surface. A first connecting portion is disposed on the base and protrudes from the front surface. A second connecting portion is disposed on the base and protrudes from the rear surface. The second connecting portion is configured for connecting to the first connecting portion of another identically formed track shoe. The front surface and the rear surface comprise a front stopper having a front stopper surface and a rear stopper having a rear stopper surface, respectively. The front stopper surface and the rear stopper surface are each disposed at an angle of less than 90° with respect to the base surface. 
     In a further aspect, the present disclosure relates to a track shoe for a track, in particular, a track of a large hydraulic excavator, comprising a plate-shaped base having a substantially rectangular base surface and being defined in a transverse direction by a left side surface and a right side surface and in a longitudinal direction by a front surface and a rear surface. A first connecting portion is arranged on the base and protrudes from the front surface. A second connecting portion is disposed on the base and protrudes from the rear surface. The second connecting portion is configured for connecting to a first connecting portion of another identically formed track shoe. A plurality of reinforcement ribs are formed on the base spaced apart from each other in the longitudinal direction and extending from at least one of the connecting portions to one of the left side surface and the right side surface in the transverse direction. 
     In yet another aspect, a track shoe for a track, in particular, a track of a large hydraulic excavator, comprises a plate-shaped base having a substantially rectangular base surface and being defined in a transverse direction by a left side surface and a right side surface and in a longitudinal direction by a front surface and a rear surface. A first connecting portion is disposed on the base and protrudes from the front surface, and a second connecting portion is disposed on the base and protrudes from the rear surface, wherein the second connecting portion is configured for connecting to the first connecting portion of another identically formed track shoe. A cavity extending in the transverse direction is formed in at least one of the first connecting portion and the second connecting portion. 
     In another aspect, the present disclosure relates to a track for a track vehicle, in particular, a large hydraulic excavator, comprising a plurality of track shoes according to one of the above aspects connected to form the track. 
     Other features and aspects of the present disclosure will become apparent from the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of a track shoe in accordance with a first exemplary embodiment; 
         FIG. 2  shows a perspective view of two track shoes in accordance with an exemplary embodiment connected to each other; and 
         FIG. 3  shows a side view of the track shoes according to the exemplary embodiment connected to each other. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, a detailed description of exemplary embodiments of the present disclosure will be given. The exemplary embodiments described herein are intended to teach the principles of the present disclosure and enable persons of skill in the arts to implement and use the present disclosure in many different environments and for many different applications. Accordingly, the exemplary embodiments are not intended to limit the scope of protection. Instead, the scope of protection is defined by the appended claims. 
     The present disclosure may be based at least in part on the realization that a track shoe for a track formed as a cast part or a forged part may improve the durability of the track shoe by increasing the strength of the same. Further, the outer portions of the track shoe can be reinforced by providing a plurality of reinforcement ribs to thereby increase the durability in particular in these portions, thereby also increasing the service life of the track shoe. 
     In addition, the present disclosure may be based at least in part on the realization that conventional designs allow for a negative rotation of the track links with respect to each other, resulting in an increased wear of the track shoes and damage to other components of the drive system of the machine, for example, a frame on which the track is mounted. Accordingly, the present disclosure is based on the realization that it may be advantageous to limit such a negative rotation. 
     Finally, the present disclosure is based at least in part on the realization that, due to the high loads during the load transfer between neighboring track shoes, high loads are applied to the running surfaces of the track shoes, which may result in an increased wear or even cracks or deformations. Accordingly, the present disclosure uses running surfaces having a constant width to avoid load concentrations in the track shoes. 
     Referring now to the figures,  FIG. 1  shows a perspective view of a track shoe in accordance with an exemplary embodiment.  FIGS. 2 and 3  show a perspective view and a side view, respectively, of two track shoes of the exemplary embodiment being connected to each other. 
     As shown in  FIG. 1 , a track shoe  10  includes a plate-shaped base  12  having a substantially rectangular base or bottom surface  13  (see  FIG. 3 ). Base  12  is defined in a circumferential direction by a left side surface  15 , a right side surface  17 , a front surface  19 , and a rear surface  21 . Here, base  12  extends in a transverse direction from a first or left end  14  to a second or right end  16 . A first connecting portion  18  and a second connecting portion  20  are disposed on base  12 . Connecting portions  18 ,  20  include several portions, as shown in  FIG. 1 , first connecting portion  18  including three portions  40 ,  42 ,  44  extending from base  12  to the front in a longitudinal direction that is perpendicular to the transverse direction and protruding from front surface  19 . On the opposite side, second connecting portion  20  also includes three portions  46 ,  48 ,  50  extending in the longitudinal direction and protruding from rear surface  21 . It will be appreciated that the terms “left”, “right”, “front”, and “rear” are used herein for the purpose of illustration to designate the respective sides of base  12  or track shoe  10  and are not limiting. 
     As shown in  FIG. 1 , portions  40 ,  42 ,  44 ,  46 ,  48 ,  50  are formed as projections or noses located on the upper side of base  12  and protruding therefrom to opposite sides in the longitudinal direction. It will be readily appreciated by the skilled person that track shoe  10  is configured such that the two opposite sides in the longitudinal direction are complementary to each other. In other words, second connecting portion  20  disposed on the rear side of track shoe  10  is configured such that it is pivotably connectable to a corresponding first connecting portion  18  of another track shoe. Likewise, first connecting portion  18  on the front side of track shoe  10  is configured such that it may be connected to a corresponding second connecting portion  20  of another track shoe. An exemplary connection is shown in  FIG. 2 . As shown in  FIG. 2 , two identical track shoes  10 ,  11  are connected to each other by pins  32  provided in through holes formed in the portions of connecting portions  18 ,  20  ( FIG. 1 ) such that they are rotatable with respect to each other about an axis of rotation A (see  FIG. 3 ) defined by the connecting portions or pins  32 . A projection  56  is provided at the center of base  12  of each track shoe  10 ,  11 , which forms an engagement portion  38  together with another such projection  56  of a neighboring track shoe. A tooth of a drive sprocket may engage with the engagement portion to drive a track  100  formed by track shoes  10 ,  11 . 
     It will be readily appreciated by the skilled person that, during use of track  100 , track shoes  10 ,  11  run on corresponding drive sprockets and idlers while being rotated with respect to each other such that, for example, track shoe  11  in  FIG. 2  is rotated upwards and base  12  of the same moves away from base  12  of track shoe  10 . In the following, this will be referred to as “positive rotation”. 
     Referring again to  FIG. 1 , in the exemplary embodiment, portions  40 ,  42 ,  44  of first connecting portion  18  are arranged spaced apart from each other in the transverse direction. Here, two portions  42 ,  44  are provided on one side (the right side) with respect to the center of track shoe  10 , while third portion  40  is provided on the other (left) side. Portion  42  closest to the center has a greater width when compared to portions  40 ,  44 . A rectangular running surface  54  is formed on the upper side of portion  42 , on which an idler of the track drive rolls during movement of track  100  in a known manner. 
     Portions  46 ,  48 ,  50  of second connecting portion  20  are formed complementary to portions  40 ,  42 ,  44  of first connecting portion  18  as mentioned above. That is to say, portion  48  having a greater width and another portion  46  are provided on the left side, while third portion  50  is provided on the right side. A rectangular running surface  52  is formed on the upper side of portion  48 . Upon connection to other track shoes, one portion  40  is inserted between portions  46 ,  48 , while the associated portion  50  is inserted in portions  42 ,  44 . Next, two pins  32  (see  FIG. 2 ) are inserted from the outside into the through holes of the respective portions and fixed, which will be described in more detail below. In order to allow for a smooth rotation of the track shoes with respect to each other, the ends of portions  40 ,  42 ,  44 ,  46 ,  48 ,  50  are rounded-off, while corresponding recesses are formed in the rear sides of the same. The upper sides of connecting portions  40 ,  44 ,  46 ,  50  are recessed with respect to the upper side of portions  42 ,  48  having running surfaces  52 ,  54  such that, during movement of the track  100 , they do not come into contact with the idlers. 
     As described above, during movement of track  100  around the idlers of the track drive, a positive rotation occurs between the same. In other words, the opposing front surfaces  19  and rear surfaces  21  of adjacent track shoes  10 ,  11  move away from each other. However, a rotation in an opposite direction may occur in regions between the idlers and supporting rollers (herein also referred to as “negative rotation”), during which front surface  19  and rear surface  21  of neighboring track shoes  10 ,  11  approach each other. This is shown, for example, in  FIG. 2 . As outlined above, the abutment of the surfaces of the track shoes  10  may result in an increased wear and damage to a frame member or the like which is disposed above the track shoes. In order to suppress this, front surface  19  and rear surface  21  of track shoe  10  include a front stopper  25  and a rear stopper  24 , respectively, formed such that, upon rotation of track shoe  11  connected to track shoe  10 , for example, rear stopper  24  of track shoe  10  abuts against front stopper  25  of track shoe  11  after rotation by a predetermined angle α (see  FIG. 3 ), which is shown in more detail in  FIG. 3 . 
     In the exemplary embodiment, stoppers  24 ,  25  are each formed on both ends  14 ,  16  of base  12  in the transverse direction, respectively. Here, stoppers  24 ,  25  have predetermined positions with respect to axes of rotation A, B defined by the respective connecting portions  18 ,  20 , which predetermined positions result in abutment of stoppers  24 ,  25  after a negative rotation by the predetermined angle α. 
     For example, front stopper  25  and rear stopper  24  each include a front stopper surface  27  and a rear stopper surface  28 , each disposed at an angle β of less than 90° with respect to base surface  13  (the plane defined by base surface  13 ), as shown in  FIG. 3 . For example, the angle β is selected such that it is equal to 90° minus the amount of one half of the predetermined angle α at which track shoes  10 ,  11  abut against each other. In this manner, it can be assured that, when stoppers  24 ,  25  abut against each other, a plane contact between corresponding stopper surfaces  27 ,  28  is obtained, resulting in reduced wear and reliably limiting the negative rotation. In some embodiments, stoppers  24 ,  25  may be formed such that an imaginary line connecting the axis of rotation A or the axis of rotation B to rear stopper  24  or front stopper  25  and perpendicular to axis of rotation A or B intersects the normal of base surface  13  at an angle of α/2 that is substantially half the predetermined angle to which the negative rotation of the track shoes with respect to each other is to be limited. 
     As described above, stoppers  24 ,  25  are formed on ends  14 ,  16  of base  12 , which may be formed as a widened end portion of base  12  with respect to the longitudinal direction. In order to reinforce these end portions, as shown in  FIG. 1 , reinforcement ribs  58 ,  60  are provided, which reinforcement ribs  58 ,  60  extend spaced apart from each other from the outer connecting portions  40 ,  46  or  44 ,  50  to the left side surface  15  or the right side surface  17  in the transverse direction. As shown in  FIG. 1 , the reinforcement ribs are formed such that they extend upwards from the left side surface  15  and the right side surface  17  and then extend inwards to merge with an upper side of portions  40 ,  46 ,  44 ,  50 . A mounting portion  62  for a fixing bolt  36  for fixing a connecting pin  32  received in first or second connecting portion  18 ,  20  is provided on one of the reinforcement ribs  60  (see  FIGS. 2 and 3 ). 
     As shown, for example, in  FIG. 3 , a groove  80  extending in the transverse direction is formed in the base surface of base  12 . The groove  80  extends from the left side surface  15  to the right side surface  17 . It should be understood, however, that in other embodiments groove  80  may be omitted. 
     It will be appreciated that numerous modifications and alterations may be made to the disclosed track shoe without departing from the scope of protection. 
     For example, in the embodiments shown in the figures, stoppers  24 ,  25  are provided on the outer ends of base  12  of the track shoe. In other embodiments, however, stoppers  24 ,  25  may be provided at different positions in the transverse direction, for example, at the center or the like. Further, in other embodiments, only a single stopper may be provided on the front side and the rear side, respectively, to limit a negative rotation. In other embodiments, more than two stoppers may be provided on each side. Further, more than two reinforcement ribs  58 ,  60  may be provided on the ends  14 ,  16  of base  12  to reinforce the same. 
     The predetermined angle α at which negative rotation between two track shoes is limited may be appropriately determined in advance depending on the application. For example, the angle α may be less than 25°, for example, between around 5° and around 25°, in particular, between 10° and 20°, for example, 15° or less. 
     Although the present embodiment has been described as a one-piece track shoe, in other embodiments, track shoe  10  may be formed from several parts. For example, connecting portions  18 ,  20  may be connected to base  12  in an appropriate manner. Further, the running surfaces provided on portions  48 ,  42  do not necessarily have to be rectangular, but they also may be Z-shaped or have any other appropriate shape. Further, the number of portions  40 ,  42 ,  44  and  46 ,  48 ,  50 , respectively, of connecting portions  18 ,  20  is not limited to three and may be more or less in other embodiments. Further, track shoe  10  does not necessarily have to be symmetric, i.e., different numbers of portions of connecting portions  18 ,  20  may be provided on the front and the rear. 
     In some embodiments, a cavity  90  may be formed in at least one of first connecting portion  18  and second connecting portion  20 , as shown by a dashed line in  FIG. 3 . Cavity  90  may extend in the transverse direction and may be opened in a side surface of one of portions  40 ,  42 ,  44 ,  46 ,  48 ,  50  of connecting portions  18 ,  20 . For example, a pair of cavities may be formed in portions  40  and  50  (see  FIG. 1 ). It will be readily appreciated that in some embodiments cavity  90  may only be formed in one of portions  40 ,  50 . Likewise, cavity  90  may extend into portions  42 ,  48  of first and second connecting portions  18 ,  20 , if desired. In some embodiments, cavity  90  may even extend into projection  56  and/or penetrate track shoe  10 , i.e., extend from the outer side surface of portion  40  to the outer side surface of portion  50 . It will be readily appreciated that cavity  90  may have any appropriate cross section in the direction perpendicular to the transverse direction, and that the cross section of cavity  90  may not be constant as it extends in the transverse direction. 
     With the provision of cavity  90 , it becomes possible to reduce the weight of track shoe  10 , which is advantageous both during operation of the associated machine and during transport of track shoe  10 . For example, a track shoe for use with a large hydraulic excavator may have a total weight of up to 800 kg, and the provision of cavity  90  may reduce the weight of track shoe  10  by approximately 5%. 
     INDUSTRIAL APPLICABILITY 
     The industrial applicability of the systems and methods disclosed herein will become readily apparent from the above discussion. An exemplary machine that is suitable for the disclosure is a large hydraulic excavator having a track drive. It will be understood, however, that the present disclosure may be applied to a number of different machines having such a track drive. 
     A method for preventing a negative rotation between two track shoes of a track includes providing stoppers on opposite sides of a base of each track shoe, the stoppers being formed such that, upon rotation of the track shoes with respect to each other, a stopper of one plate abuts against an opposing stopper of the neighboring plate at a predetermined angle to limit the negative rotation. The method may further include providing reinforcement ribs that extend outwards on ends of the base of each track shoe to reinforce said ends. Further, the method may include providing widened connecting portions in the vicinity of a center of the base of the track shoe, where a substantially rectangular running surface is formed on the same. 
     It will be readily appreciated that the above description provides examples for the disclosed system and methods. It is also contemplated, however, that other implementations of the disclosure may differ in detail from the above examples. All references to the disclosure or to examples of the same are intended to refer to the particular example discussed at that point and are not intended to limit the scope of the disclosure in general. All methods disclosed herein may be performed in any appropriate order, unless otherwise indicated herein or contradicted by context. 
     Accordingly, this disclosure includes all modifications and equivalents of the subject-matter of the appended claims to the extent allowed by law. Further, any arbitrary combination of the above-described elements in all possible variations is encompassed by the disclosure, unless otherwise indicated herein or contradicted by context. 
     Although preferred embodiments of the disclosure have been described herein, improvements and modifications may be included without departing from the scope of the following claims.