Abstract:
A track for in-line tires on a skid steer vehicle, the track includes a continuous loop of links with sidebars and a pin and a barrel, the pin and barrel together forming a hinge between the links and extending between the sidebars. Tire side guides extend upward from the side bars to guide the tires along a pathway over the upward side of the hinges. The opposite side of the hinges engage the ground. The tire side guides can be permanently attached or temporarily fastened to the sidebars at selected positions and moved to other selected positions to convert the track for use with different sized tires, thereby proving a convertible track and a method of converting a track. A system for forming and closing the track as a loop of links is also disclosed.

Description:
BACKGROUND OF INVENTION 
     The present invention relates to tracked vehicles and in particular relates to tracks for skid steer vehicles. 
     Skids steer vehicles are commonly encountered in the construction, landscape, agricultural, or lumber industries. Typically, skid steer vehicles have a pair of in-line tires on each side of the vehicle. To advance, both pairs of the tires are rotated in the same direction; to turn the skid steer vehicle, the tires on one side of the vehicle are rotated in opposition to tires on the opposite side. While such vehicles are quite useful, under some conditions, the tires lack adequate traction with the ground. That is, in mud or upon ice, one or more of these tires lose traction with the ground and dig into the ground or slide sideways. Such performance is unacceptable under work conditions and may even be dangerous. Providing tracks has been an oft considered and sometimes employed alternative. 
     The available track systems for skid steer vehicles, however, also have some considerable drawbacks. One such system is an entirely rubber track. Rubber tracks are extremely expensive and not particularly durable. Another such system is a “grouser” type track. Grouser tracks may be described as plates, with a short connector on either side of the plate, used to provide a track for the tires of the skid steer. The two short links of the grouser track are not in the plane traveled by the tires but rather displaced upward from the plane traveled by the tires. As such, they generate what might be described as a pair of hinge points on each side of the plates in the grouser type track. The distortion resulting from four hinge points allows considerable and undesirable flexibility between adjacent grouser plates. Again, the grouser track suffers from a high price and limited durability. Both forms of tracks also suffer from a performance issue in which the track twists when not directly in contact with a tire. When traversing over a rock or stump or similar obstacle, the track particularly twists in the ground contact segment between the tires and the skid steer vehicle slides unexpectedly sideways. 
     It would be highly desirable to provide a less expensive track with better performance characteristics than those currently available from rubber tracks or grouser style tracks. 
     SUMMARY OF THE INVENTION 
     In an effort to address the expense and undesirable performance characteristics available from rubber or grouser type tracks, this inventor happened upon the serendipitous discovery that existing commercial chains, in extensive use in alternative industries might be modified and adapted for use as skid steer tracks. In particular, this inventor observed that certain chains, known as drag chains, commonly employed to move bulk materials through conveyors in sawmills, pulp and paper mills and similar industries might be employed, with inventive modifications, as tracks for skid steer vehicles. Such chains typically are pulled by a power sprocket adjacent a discharge of a conveyor. An idler sprocket at the beginning of the conveyor trough typically serves to maintain the drag chain in a desired position with the end of the trough. In conveyor use, side adapters are also often employed to maintain the drag chain in the desired position within the trough. Many, but not all, of the attributes desired for a skid steer vehicle track are present in such drag chains. Notably, such chains are relatively durable, having been developed for continuous use dragging bulk materials through a trough to move materials in a specific direction. Further, the chains are produced in substantial quantity, rather than being a high-priced specialty item. Thus, the basic chain, without the tire side guides and modifications of this invention is relatively inexpensive, Moreover, the single hinge formed between each link of a drag chain extends from one side to the other, rather than being two separate smaller hinges on each side of a grouser plate, and therefore would, in theory, allow less “twist” than a grouser style track or a rubber track. 
     In a first embodiment, a track for a skid steer vehicle according to the present invention, includes a plurality of links. Each link has a pin, a first and second sidebar extending radially from the pin, and a barrel attached to the opposite ends of the sidebars. The sidebars also include an inset-jog which narrows the space in-between the sidebars to correspond to the shorter barrel length. The barrel is rigidly attached to the sidebars. The pin is also radially locked with respect to the side bars. Assembled as a chain, the pin is captured or encased within the barrel. The pin and barrel together form a hinge between sequential links. Moreover, the hinge defines a tire support surface for a tire of the skid steer vehicle on a first side and a ground engaging support on the second side. Projecting from the sidebars, on the first side, are a pair of tire side guides. The tire side guides defined the edges or lateral boundaries of a guided pathway for the tire of the skid steer vehicle over the tire support of the barrel-pin hinge. Preferably, at least the basic chain (i.e. sidebars, barrel and pin) is formed of hardened steel, for example, heat tempered steel. 
     In some situations, the ends of the chain may be joined to one another and form a perfect fit, or near perfect fit, for a pair of in-line tire of a skid steer vehicle. This is due to the appropriate track length equaling a multiple of links. In other situations, a spacer link must be employed. In one embodiment of the present invention, the spacer link may be a separable bar with a pin end and a barrel end. The two separable parts of the spacer bars may be joined by a bolt and nut arrangement. In another embodiment of the present invention, the spacer link may include a plurality of apertures or holes so that the correct spacing may be selected from amongst the plurality of apertures. Most preferably, the connector system to close the loop has a short portion of bar at the the barrel and the pin, each of the bars have an aperature, and a connector segments with apertures are used to connect the two bars. A spacer is used to correct for a difference in lateral offset between the pin and barrel. If a plurality of connector segments are available with different lengths, wear can be accommodated. 
     In another embodiment of the present invention, a plurality of tire sizes may be accommodated by a single chain. This is due to the alternative spacings between the sidebar carried tire side guides provided by the offset-jog. That is, tire side guides carried adjacent to the barrel will be spaced to accommodate relatively narrow tires. Tire side guides carried adjacent the pin will be spaced to accommodate relatively wide tires. Tire side guides carried at the offset-jog will accommodate intermediate width tires. 
     In still another embodiment of the present invention, a plurality of tire sizes may be accommodated by a single modified chain in an interchangeable manner, by providing a plurality of attachment points at the earlier identified positions along the side bars. This interchangeability is achieved in combination with removable or separable tire side guides which can be interchangeably attached to a selected one of such positions. Preferably, such tire side guides are bolted for attachment to the side bars at desired positions. Most preferably, the attachment system further includes a means for preventing rotation about the attachment bolts. For example, a second bolt might be provided, an interacting flange, either above or below the side bar, or a supplemental pin arrangement. 
     In yet another embodiment of the present invention, a plurality of tire sizes maybe accommodated by providing tire side guides, with a relatively wide spacing, in combination with a tire side spacer. Alternatively, a variety of tire side spacers may be employed on one or both of the tire side guides to provide many optional tire width spacings. 
     In still another embodiment of the present invention, attachments for ground interacting or ground engaging accessories maybe provided on the links. In such a manner, a variety of the ground engaging accessories may be removably attached. Preferably, such ground engaging accessories are attached to the side bars. In one variation, where the sidebars carry a plurality of attachment apertures for moveable tire side guides, an un-occupied aperture may be used to attach the accessory. Alternatively, the ground engaging accessories in may be reversibly attached to the hinge, formed from the pin and barrel combination. Depending upon whether the exterior of the hinge moves with either the current link or the adjacent link, the accessory may be engaging the ground in a leading or following manner. In contrast, accessories carried on the side bar are always engaged with the remainder of the link. Alternatively, a dedicated attachment point may be provided for ground engaging accessories. If so, it is preferred that the dedicated attachment for accessories be a vertically oriented aperture (relative to the hinge axis.) 
     In other embodiments of the current invention, the present invention is a method of converting to a convertible chain by the steps of: providing a chain formed of links according to the appropriable descriptions and altering the spacing between the tire side guides (or tire side guides which spacers) and the center line as defined by mid points of the hinge formed by the barrel and pin combination of two adjoining links. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 shows a top view of a segment of chain with sidebars of links modified according to the present invention; 
     FIG. 2 shows a skid steer vehicle with a track according to the present invention; 
     FIG. 3 a , shows a spacer bar for joining chain ends and FIG. 3 b  shows a plurality of alternate spacer bars, each of which is separable, for joining chain ends; 
     FIG. 4 shows a top view of a segment of chain with sidebars of links modified for narrow tires; 
     FIG. 5 shows a top view of a segment of chain with sidebars of links modified for intermediate width tires; 
     FIG. 6 shows a top view of a segment of chain with sidebars having a plurality of attachment points; 
     FIG. 6 b  shows a side view of a portion of a sidebar of FIG. 6; 
     FIG. 7 shows a side view of three alternative removable tire side guides; 
     FIG. 8 shows an end view of the embodiment of FIG. 1; and, 
     FIG. 9 shows an end view as in FIG. 8 but including a tire spacer between the sidebars and the tire side guides, thereby altering the spacing between the tire side guides. 
    
    
     DETAILED DESCRIPTION 
     In a first embodiment, the present invention is a track,  20  of FIG. 1, for a skid steer vehicle  22 . The skid steer vehicle  22 , shown in FIG. 2, has fore and aft in-line tires,  24  and  26 , on the left side  28  and fore and aft in-line tires  30  and  32  on the right side  34 . Preferably, each pair of in-line tires  24  and  26 , as well as  30  and  32  respectively, engages a substantially identically arranged track  20 . Alternatively, it is possible to arrange the left hand track  20 L engaging left-hand tire pair,  24  and  26 , in a first orientation, and to arrange the right hand track  20 R engaging the right-hand tire pair,  30  and  32 , in a second orientation, opposite to the first orientation, as will be clear once the invention has been explained in additional detail below. 
     The track  20  may be understood as a chain  40  of numerous repeating links  42   i ,  42   i +1, and so forth, as shown in FIG.  1 . Each link  42  has a pin  44  with a pin axis  46 , a first pin end  48  and a second pin end  50 . A first side bar  52  extents radially outward from adjacent the first pin end  48  of the pin  44 . The first side bar  52  has a connecting end  54 , which is radially locked relative to the pin  44 . A second sidebar  60  extents radially outward from adjacent the second pin end  50  of the pin  44 . The second sidebar  60  is radially locked relative to the pin  44 . The second sidebar  60  has a connecting end  62 . The second sidebar  60 , achieves its radial locked relationship with pin  44  due to a longitudinally extending flat interacting with a cooperatively shaped aperture in connecting end  62 . A similar arrangement is present at connecting end  54 . 
     A barrel  70  is present at barrel end  72  of sidebar  52  and barrel end  74  of sidebar  60  and is located between these ends  72  and  74  of the sidebars  52  and  60 . The barrel  70  has a barrel axis  76 , which, when assembled as a chain  40 , is shared with the pin axis  46  of an adjacent link. The barrel end  72  of sidebar  52  is permanently attached to the end  78  of barrel  70 , as is barrel end  74  of sidebar  60  to other end  80  of barrel  70 . The barrel ends project radially outward from the barrel  70 . The barrel  70  is not as long as the pin  44  but encases or captures the pin  44  of the adjacent link  42   i +1. Between the connecting end  54  and the barrel end  72  of side bar  52  is an inset-jog  82  and a complementary inset-jog  84  is present in the second sidebar  60  between the connecting end  72  and the barrel end  74 . The inset-jogs  82  and  84  narrow the spacing between the sidebars  52  and  60 , such that the barrel  70  is carried spaced apart from and parallel to the pin  44  in an aligned relationship between the first sidebar  52  and the second sidebar  60 . The barrel  70  of the link  42   i  and the pin  44  of the next link  42   i +1 form a hinge  100  between the adjacent links. The chain  40  may be considered as a sequence of links with hinged connections between the links. Each hinge  100  has a midpoint  102 , which is the midpoint of the pin  44  and the barrel  70 . The midpoints  102  define a pathway  104  over the hinges  100 . That is, a first side of the hinge  100  provides a support surface for supporting, sequentially, individual tires of the pair of in-line tires of the skid steer vehicle. The tire support surface of the hinge and the side of the link and chain facing generally in the same direction as the tire supporting surface may best be understood as being directed upward. The downward or opposite side of the hinge  100  engages the ground surface beneath the tires. The barrel has one flat vertical side  71 . The ground surface is also engaged by the sidebars  52  and  60 , and in particular by a lower edge of the sidebar. Other ground engaging devices may also be involved as will be explained in greater detail subsequently. 
     The in-line tires  24  and  26  or  30  and  32  can move along the pathway  104 . However, the tires, for example  24  and  26 , have an undesirable tendency to stray off the pathway  104 . This undesirable tendency is most pronounced when the skid steer vehicle is undergoing a turning operation with one set of in-line tires counter-rotating the other in-line set of tires. To counteract the undesirable tendency to stray off the pathway  104 , a guide system to guide the tires along the pathway has been invented, to guide tires, for example tires  24  and  26 , along the pathway  104 . 
     In one embodiment, a first tire side guide  120  projects upwardly, i.e. in the tire support direction and away from the ground engaging direction, from the first sidebar  52 . A second tire side guide  130  projects upwardly from the second side bar  60 . These two tire side guides form a lateral boundary on each side of the pathway  104  over the tire support surfaces of the hinges  100 . At the greatest extent of the tire side guides,  120  and  130 , is an axial flare  122  and  132 , respectively. These axial flares  122  and  132  serve to further guide an approaching tire into alignment between the tire side guides  120  and  130  and on the pathway  104 . The axial flares  122  and  132  might be understood as broadening the entrance into the space between the tire side guides  120  and  130  and further protecting the tires and particularly the sidewalls of the tires from puncture or excessive abrasion by the tire side guides  120  and  130 . As a tire rolls away from the region under control of the tire side guides  120  and  130 , the axial flares  122  and  132  ease the exit of the tire and again protect the tire from tearing or snagging. As the tire passes by, it first rolls into a situation of being temporarily captured between the tire side guides  120  and  130  and upon the pathway  104  and then continues to roll out of control of the tire side guides  120  and  130 . However, the adjoining link, which is next encountered by the tire moving along the pathway  104 , also has an set of tire side guides  120  and  130 , each with an axial flare  122  and  132  and thus control of the tire is handed off to the next link. As the tire continues along the pathway  104 , support and guidance is repeatedly provided by the links of the track. Reversal of direction of tire rotation similarly reverses the control back to the earlier encountered tire side guides. 
     Having thus described the interaction of the tires with the tire support provided by the hinges  100  and the tire side guides  120  and  130 , another feature will be explained. Because the sidebars  52  and  60  have a first spaced apart relationship adjacent the pin and a narrower spaced apart adjacent the barrel, two spacings from the center line of the pathway are available for the tire side guides  120  and  130  of this embodiment. An additional intermediate attachment spacing is available at the offset jog of each of the sidebars  52  and  60 . While it is preferred that the tire side guides  120  and  130  are laterally opposed to each other, i.e. equally spaced from hinge  100 , it is also possible to have one tire sidebar adjacent the pin  44  and the other adjacent the barrel  70 . 
     The tire side guides  120  and  130 , in a first embodiment, are welded to the respective side bars  52  and  60 . In an alternative embodiment, the tire side guides  120  are removably attached to the sidebars  52  and  60 , for example by bolts. In a preferred embodiment, the sidebars  52  and  60  have a plurality of apertures or bolt accepting holes so that the tire sides bars may be selectively attached at a spacing which will allow the skid steer tire size to be coordinated with the track. If the track is later to be used with a different tire size, the spacing between the tire side guides  120  and  130  then may be altered by shifting one or both of these guides to a different attachment aperture. 
     In yet another embodiment, the tire side guides  120  and  130  are modified by the addition of a spacer  140 . The spacer  140 , if on the inside edge of the sidebar, narrows the distance across the track to accommodate narrower tires or alternatively, broadens the spacing if placed on the outside of the sidebar. 
     To install the track of the present invention on a skid steer vehicle, it is preferred that a track be installed on each side of the skid steer (i.e., the track of the present invention is intended to be used as one of a pair of tracks.) The preferred installation may be accomplished by the following steps. First, the pair of tracks,  20 R and  20 L, are deployed on the ground in a parallel and spaced arrangement with the tire contacting portion of the hinges  100  directed upward. At this point, each track has a beginning and an ending link and the length of each track is roughly equal to or slightly exceeding the circumference of one of the side tires plus double the distance between the axels supporting the tires. The spacing between the tracks should be approximately the same as the spacing of the tires from one side to the other side of the skid steer. Next, the skid steer  22  is maneuvered onto the deployed tracks  20 R &amp;  20 L by driving onto the tracks from an end of the tracks. Preferably, the tracks of the pair are arranged such that the flat side of barrels of both tracks are directed in the same direction. In performing this step in the installation, the orientation of the barrel flat sides  71  may be selected by the orientation of the skid steer direction relative to the flat sides  71  of the barrels. For example, in an anticipated use of the skid steer where maximum ground engagement is required when the skid steer will be backing up, the barrel flat sides  71  should be directed forward where they engage the ground. In contrast, in an anticipated use of the skid steer where maximum ground engagement is required when the skid steer is pulling forward, the flat sides of the barrels should be directed rearward where they engage the ground. The skid steer, after traversing the ends in the desired direction, continues to roughly a mid-point of the tracks. Next, the leading and trailing ends of each track are lifted over the tires such that the two ends approach being adjacent and aligned with each other. Due to the weight of tracks, it may be helpful and or necessary to provide a compression mechanism to pull the ends closer. A hand winch, pliers, a windlass or similar mechanism may be used to accomplish this pulling step step. Next the ends are joined to form an endless loop of track on each side of the skid steer. 
     In joining the ends, two distinct approaches are available, depending upon the relationship of the length of track and the size of the skid steer upon which they are being mounted. In a first approach, the length of track and the skid steer are in a nearly ideal relationship. In this approach, a modified pin  45  is used to join the ends. The modified pin  45  has a threaded end which is held in place by a nut  47 . The modified pin  45  nearly perfectly substitutes for the original pin  44 . The modified pin  45  has a flat which retains it relationship to the sidebar  52  or  60 , such that wear between the interior of the barrel  70  and the modified pin  45  occurs across the entire interior of the barrel  70 , rather than wear occurring between the much narrower engagement of a pin  45  (or  44 ) and the side bar ( 52  or  60 .) It will be recognized, however, that eventually wear of the tires and the track will cause the nearly ideal relationship to be lost. In such circumstances, the second approach to joining the ends is encountered. 
     In the second approach to joining the ends of the tracks, the nearly ideal relationship either is not present to begin with or has occurred as a result of wear. In this situation, a joiner link system  160  is employed. The joiner link system  160  maybe understood as an appropriate substitute for the sidebars,  52  and  60 , providing a more appropriate length. Preferably, a plurality  164  of joiners  162  may be supplied to allow selection of a plurality of lengths, and the most appropriate length selected. A joiner-spacer  166  is also supplied to provide lateral spacing. The connectors  168  for the joiners  162  are preferably a square stock or shank  170 , with a rounded head  172  on one end and a threaded portion  174  on the other end. In one embodiment, the rounded heads are directed to the outside of the track on each side and nuts are employed on the inside of each track. Alternatively, as shown in ghost outline, the heads may also be situated on the inside and the nuts employed on the outside of the track. Apertures are also provided to accommodate and key to the square stock of the connectors. Preferably, the square stock or shanks of the connectors are ¾ inch steel and the apertures are just slightly greater square holes. Alternatively, a ⅝ inch hole might be used. One of ordinary skill will recognize that the connectors serve to prevent pivoting between the pin and barrel hinge  100  on one side of a joiner  162  and the pin and barrel hinge  70  on the other side of the joiner  162 , and thus other known systems to prevent pivoting are within the scope of the joiner link system  160  of the present invention, while providing a plurality of lengths from which to select. Further, one of ordinary skill will recognize that track and tire wear may need to be accommodated more than once over the long life of such systems. It should be further pointed out that operational and manufacturing efficiency results from each link of the track being originally provided with such square apertures in the side bars  52  and  60  as well as joiner  162 , and joiner-spacer  166 . Should a link break or otherwise require repair or modification or alteration of track length, merely cutting sidebars  52  and  60  allows an expeditious repair, even in the field if so required. Moreover, the provision of such apertures  176  in the sidebars  52  and  60  allows for tire side guides  120  and  130  to mounted or modified in spacing as needed. Further, the apertures  176  not employed for tire side guides or joining remain available for mounting ground engaging accessories. 
     As shown in FIG. 6 b , sidebar  52  has an inset-jog  82 , and may have square apertures  176  on either side of the inset-jog  82 , such that tire side guides may be selectively attached with square shank bolts. 
     To remove the tracks, the process is generally reversed, removing a pair of connectors  168  from each track and driving off of the track with the skid steer vehicle. To modify the tracks for a different tire size, in this apertured embodiment, the tire side guides  120  and/or  130  or both are moved to different locations on the sidebars  52  and  60 , generally relative to the inset jog  82  or a spacer, such as joiner-spacer  166  is inserted or removed, as appropriate. Optionally, the ground engaging accessories utilize unused apertures. Ground engaging accessories include spikes, flotation plates, vertical plates, cleats, etc. Absent any accessories, the present track is remarkably capable of dislodging any mud through the relatively large openings of the links. As such it is less prone to damaging a skid steer with a track than a comparable grouser-type or rubber track. 
     Those of ordinary skill will recognized that skid steer vehicles have well known safety concerns associated with them that are oft times associated with guards and interlock mechanisms, and such safety concerns and precautions, although not the subject of this application, should not be disregarded nor disabled in practicing the present invention. Various modifications can be made to the present invention without departing from the spirit of the invention.