Abstract:
A traction stud for an endless snowmobile belt including an elongate rod having a ground engagable end and a threaded end which can be coupled to the track with a threaded fastener. A slot is cut into the threaded portion of the track such that the terminal end threaded portion is separated from the remaining threaded portion by a gap but coupled thereto via a reduced stem which, after installation, can be broken away so that the remaining portion of the stud shank is flush with the fastener. The invention also contemplates the method of making the stud and the method of installing the stud with a transverse slot providing a weakened break away portion which can be severed by the application of transverse force to remove the axially inner terminal end of the stud.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a traction device and more particularly to a snowmobile stud having an inner terminal end portion which is broken away from the remainder of the stud after installation on an endless snowmobile belt. 
     2. Description of the Prior Art and Objects 
     Studs for snowmobile tracks have been provided heretofore such as that illustrated in U.S. Pat. No. 5,234,266 issued to James R. Musselman et al on Aug. 10, 1993, U.S. Pat. No. 5,299,860 issued to Lynn J. Anderson on Apr. 5, 1994, and the U.S. Pat. No. 4,758,055 issued Lynn J. Anderson on or About Jul. 19, 1988. 
     Such snowmobile studs are sometimes referred to as pass-through studs each having a shank which passes through an opening in the track and integrally mounts, at one end, an integral head which bears against the inner surface of the track. A nut is threaded onto the stud on the outer surface of the track. 
     Another type of ice stud is that illustrated in U.S. Pat. No. 3,973,808 issued to Jansen et al on Aug. 10, 1976 and assigned to James R. Musselman. A similar type stud is illustrated in U.S. Pat. No. 3,838,894 issued to Donald G. Reedy on Oct. 1, 1994 and U.S. Pat. No. 5,401,088 issued to Edward R. Rubel on or about Mar. 28, 1995. 
     Each of the three latter mentioned patents discloses a snowmobile stud having an axially outer ice penetrating pointed end and an axially inner end which is received in an aperture provided in a snowmobile belt. An enlarged tool engageable midportion mounts a plate or washer which bears against the outer track surface. A so-called &#34;T-nut&#34; is threaded onto the threaded inner end of the shank to securely fasten the stud to the snowmobile belt. As the stud is threaded into the threaded fastener, the snowmobile belt, which is resilient, will typically compress between the washer and T-nut. After installation, depending upon the thickness of the belt, an axially inner terminal end portion of the ice stud may project axially inwardly of the threaded fastener. If the axially inwardly projecting terminal stud end happens to be aligned with the idler wheels and drive sprocket wheels, undesirable stud breakage and track vibration can result. Accordingly, it is an object of the present invention to provide a new and novel traction stud which will minimize vibration and stud breakage. 
     Sometimes, a backer plate is mounted on the inside of the track with apertures therethrough which receive and pass the axially inner ends of the studs before the nuts are threaded onto the axially inner ends of the studs. These backer plates are of varying thicknesses depending on the material utilized. In the prior art, if the stud is of sufficient length to allow the nut to threadedly engage the terminal end of the stud mounted on a relatively thick backer plate, when mounted on a relatively thinner backer plate, the terminal end of the stud will project axially inwardly beyond the inner face of the nut and track. Accordingly, it is an object of the present invention to provide a stud which will accommodate backer plates on the inside of the track of differing thicknesses and yet, not interfere, after installation, with the idler rollers or idler sprocket wheels. 
     It has been found according to the present invention, that if, after installation, the axially inner terminal end portion of the stud is removed, the remaining portion of the stud will be flush with the threaded fastener to preclude interference of the stud with the idler sprockets and drive sprocket wheels. Accordingly, it is an object of the present invention to provide a new and novel stud having an inner terminal end portion which can be easily and quickly removed from the stud after installation on a snowmobile track. 
     A further object of the present invention is to provide a method of making a stud and method of installing a stud which will include a break away inner end portion that is removed after the stud is installed on the track. 
     It has been found according to the present invention, that a slot may be cut into the stud shank to provide a gap between an axially inner terminal end and an axially outer threaded portion, but coupled thereto via a reduced thickness stem that can be broken away by the application of transverse force thereto. Accordingly, it is an object of the present invention to provide a new and novel traction device including an axially inner threaded portion having a slot cut therein to provide a reduced thickness stem coupling an axially outer threaded end portion of the snowmobile stud to the adjacent threaded portion of the shank. 
     It is yet another object of the present invention to provide a snowmobile stud having an axially inner threaded shank provided with an annular slot that provides an annular gap surrounding a stem having a truncated cone. 
     It has been found, according to the present invention, that by shaping the stem such that the smallest diameter portion thereof is axially outermost and immediately adjacent the axially outer threaded portion, that the stem, upon the application transverse force, will break away immediately adjacent to the axially outer threaded portion. Accordingly, it is an object of the present invention to provide a stud for a snowmobile belt or the like for the type described including a stem that has its smallest diameter at the axially outermost portion thereof. 
     It is yet a further object of the present invention to provide a traction stud of the type described including a breakaway coupling stem having a cross sectional area immediately adjacent to the axially outermost threaded portion that is smaller than any of the remaining cross sectional area of the stem. 
     It is another object of the present invention to provide a stud for a snowmobile track or the like including an axially inner threaded portion for fastening to a snowmobile belt and including an annular slot of the type described surrounding a frustoconically shaped stem having a side wall which converges radially inwardly in an axially outer direction. 
     Other objects and advantages of the present invention will become apparent to those of ordinary skill in the art as the description thereof proceeds. 
     SUMMARY OF THE INVENTION 
     A traction stud for mounting on an endless snowmobile drive belt or the like comprising an elongate rod having an elongate axis, an axially outer ground engaging end, and an opposite, axially inner track mounting end having an axially inner terminal end, and a tool engageable portion intermediate the ends; the track mounting end includes an elongate threaded shank of predetermined breadth for threadedly receiving a complementally threaded mounting nut, and a slot is cut into the elongate threaded shank axially outwardly of the terminal end to provide a break away stem having a reduced breadth relative to the predetermined breadth of the threaded shank. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The invention may be more readily understood by referring to the accompanying drawings, in which: 
     FIG. 1 is a side elevational view of a snowmobile incorporating a snowmobile stud constructed according to the present invention, parts of the snowmobile being broken away to more particularly illustrate the snowmobile belt and part of the snowmobile belt being illustrated partly in section to more particularly illustrate the snowmobile stud, constructed according to the present invention, after installation but prior to final assembly; 
     FIG. 2 is a greatly enlarged sectional side view of the portion of the track and stud illustrated in the chain line circle 2--2 of FIG. 1 subsequent to the installation but prior to having the axially inner end being broken away; 
     FIG. 3 is a sectional side view, similar to FIG. 2, illustrating a prior art construction; 
     FIG. 4 is a side elevational view of the stud, turned 90° relative to its position in FIG. 2, prior to installation; 
     FIG. 5 is a perspective view of a hexagonal bar stock illustrating the first step of manufacture; 
     FIG. 6 illustrates a subsequent step in the manufacturing process wherein the hexagonal bar stock, illustrated in FIG. 5, is machined at opposite ends; 
     FIG. 7 illustrates a subsequent step in the manufacture more particularly illustrating an axially inner, shank end being threaded; 
     FIG. 8 is a side elevational view, similar to FIG. 7, illustrating a subsequent manufacturing step wherein an annular slot is cut into the axially inner threaded shank end; 
     FIG. 9 is a further greatly enlarged fragmentary side elevational view of the connecting stem portion encircled in the chain line circle 9--9 of FIG. 8; 
     FIG. 10 is an exploded sectional side view of the ice stud prior to installation on a snowmobile belt and prior to coupling to a T-nut; 
     FIG. 11 is a side elevational view of the ice stud illustrating a subsequent step of the assembly after the stud is installed on a snowmobile belt; and 
     FIG. 12 is a side elevational view of the ice stud in a final step of assembly, illustrating the axially inner portion being broken away by a pair of pliers or the like. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     A traction stud, generally designated 10, is particularly adapted for use on a snowmobile, generally designated 12, which includes a forward rotatable drive wheel sprocket wheel 14, a rearward, rotatable idler wheel 16 and a plurality of smaller diameter idler wheels 17. An endless, resilient snowmobile track, generally designated 18, is trained around the wheels 14, 16 and 17 for movement in an endless path of travel, illustrated by the arrow 20. The track 18 may include a plurality of integral cleats 19 spaced along the outer track surface 21. 
     The front drive sprocket wheel 14 is mounted on a shaft 22 which is coupled to a gasoline engine (not shown) mounted on the snowmobile hull 24, as usual. The snowmobile includes a suspension system, generally designated 26, including wear strips 28 which glide along the inner surface 30 of the lower run 32 of the track 18. Such weather strips may suitably comprise nylon or other suitable plastic material. 
     The stud 10 may be machined from an elongate bar 34 (FIG. 5) of stainless steel stock. The stud 10 includes an enlarged, intermediate flange portion 36 having a plurality of wrench receiving flats 38 defining a multi-sided head which can be accommodated in a socket wrench or the like used to turn the stud 28 about its longitudinal axis 40 (FIG. 4). The bar 34 is machined at an axially outer end, generally designated 42, to provide a tapering or conically shaped ground engaging portion 44 which has a diameter that gradually decreases towards the tip 46. 
     The ground engaging portion 44 of the stud axially outward of the intermediate wrench receiving section 36 has a gradually reduced diameter in an axially outward direction and includes an axially extending, axially aligned, cylindrical recess or receptacle 48 receiving a hardened wear member or rod 49 fabricated from wear resisted material, such as tungsten, carbide, or the like. The insert 49 is detachably held in the recess 48 via a press fit and/or solder (not shown). The terminal portion of the carbide wear rod 49 has outwardly converging side faces 50 defining a conical point 51 (FIG. 4). 
     The opposite, axially inner track engaging end 54 of the bar 34 is threaded along its length with a uniform thread 56 (FIG. 7) for receiving the internally threaded cylindrical collar portion 58 (FIGS. 2 and 10) of a so-called T-nut, generally designated 60, having an enlarged diameter track engaging head 62 provided with two or more circumferentially spaced apart tangs 64 which penetrate into the upper inside track surface 30 of the track 18. The tangs 64 dig into the inside track surface 30 to inhibit rotation of the T-nut 60 as the stud 10 is being threaded thereon. 
     An annular slot 66 is cut into the track engaging threaded portion 56 to provide a narrow gap 68 which divides the thread 56 into an axially inner threaded portion 70 and an axially outer portion 72. The axial length of the slot 66 is substantially less than the axial length of the T-nut threaded collar 58 so that the collar 58 can bridge the slot 66 and simultaneously threadedly engage axially inner and outer portions 70 and 72 as the stud is being threaded into the nut 60. The axially outer portion 74 (FIG. 9), immediately adjacent the axially outer threaded section 72, of the slot 66 is cut to a deeper depth than is the axially inner slot portion 76 immediately adjacent the axially inner threaded portion 70 to provide a frusto-conically shaped stem 78 having an annular side wall 79 which converges radially inwardly in an axially outer direction. The stem 78 is integrally coupled to the axially inner threaded section 70 via an axially inner stem portion 84 of a predetermined breadth or diameter B which, as illustrated, is substantially less than one-half the breadth or diameter D of the threaded sections 70 and 72. The stem 78 is integrally coupled to the axially outer threaded section 72 via an axially outer stem portion 82 of a substantially lesser breadth or diameter b than the breadth B of coupling stem portion 84. 
     PRIOR ART 
     A prior art construction of the type illustrated in the Reedy U.S. Pat. No. 3,838,894 is illustrated in FIG. 3 and includes a stud 10A having an axially inner threaded section 56A threadedly received by a T-nut 60A having an enlarged head 62A flush with the inner track surface 30A of a track 18A. Depending on the axial thickness of a washer or grouser bar 40A, mounted atop a wrench receiving, intermediate flange 36A, the axially inner threaded end 70A of the threaded shank 56A extends inwardly of the inner track surface 30A. This projection 70A will sometimes strike the sprocket wheels 40 causing the stud 10A to fracture and/or create vibration which is disadvantageous. 
     THE METHOD OF MANUFACTURE 
     The stud 10 is manufactured from a piece of hexagonal, stainless steel bar stock 34, illustrated in FIG. 5. The axially outer end 42 of the bar is machined to provide the tapered, shaped ground engaging end 44. The opposite end is machined to provide the reduced diameter shank 54 (FIG. 6). The thread 56 is then cut into the reduced diameter shank 54 as illustrated in FIG. 7. The axially extending cylindrical slot 48 is also drilled into the ground engaging end 44 along the stud axis 40 for receiving the carbide rod 49. 
     The slot 66 is then cut into the threaded shank 54 to provide the tapering break-away stem 78 which is in the shape a truncated cone. The axially outer end 82 of stem 80 has a predetermined diameter or breadth b which is substantially less than the diameter or breadth B of the axially inner stem end 84 such that when side-wise or transverse force is exerted on the axially inner threaded end 70, in the direction of the arrow 81 (FIG. 11), the axially outer break away stem portion 82 will fracture or fail adjacent the axially outer threaded portion 72. 
     A solder drop is deposited into the end slot 48 and the hardened carbide wear member 49 is then inserted into slot 48 to the position illustrated in FIGS. 4 and 11. 
     THE METHOD OF INSTALLATION AND ASSEMBLY 
     To assemble the stud, a plurality of apertures O (FIG. 10) are cut or punched into the belt 18 so that the openings O are neither longitudinally nor transversely aligned. A threaded collar portion 58 of the T-nut 60 is inserted into each opening O from the inside 30 of the track 18. A stabilizing washer or plate 40 is then placed over the threaded stud end 54 in abutting relation with the wrench engaging flange 36 in the position illustrated in FIG. 10. The washer bearing threaded stud end 56 is then inserted into the track opening O from the outside 21 of the track 18. Instead of inserting the threaded stud end 56 into a washer 40, the threaded stud end 56 may be inserted through an opening provided in an inverted U-shaped cleat or grouser bar (not shown) conventionally found on having a snowmobile track. The thicknesses of the grouser bars or washers 40 can vary depending on the type of material. 
     The threaded shank portion 56 is then threadedly engaged with the T-nut sleeve 58 by means of a wrench engaging the wrench engaging flats 38 until the tangs 64 are embedded in the inside surface 30 of the belt 18 and the outer surface 61 of the T-nut head 60 is flush with the inside track surface 30 as illustrated in FIG. 11. A pair of pliers 96 is then used to grip the axially inner threaded shank portion 70 to apply side-wise force, in the direction of the direction of the arrow 81, which causes the axially inner threaded portion 70 and axially inner stem end 84 to transversely, radially outwardly bend, relative to the axially outer threaded portion 72 and relative to the axially outer stem end 82. The bending causes the radially outermost portion of the axially inner threaded section 70 to axially move toward the confronting portion of the axially outer threaded section 72 to close a portion of the gap 66 remote from the stem 78. This transverse force causes the truncated cone shaped break-away stem 78 to break, fail, or fracture along its axially outer end 82 adjacent the axially outer threaded portion 72. The resulting construction is as illustrated in FIG. 12 wherein the objectionable, axially inner projecting portion 68, 72 is removed so as not to interfere with the idler and sprocket wheels 14, 16 and 17. 
     It is to be understood that the drawings and descriptive matter are in all cases to be interpreted as merely illustrative of the principles of the invention, rather than as limiting the same in any way, since it is contemplated that various changes may be made in various elements to achieve like results without departing from the spirit of the invention or the scope of the appended claims.