Traction Device

This invention relates to a traction device for mounting on the wheels of vehicles to assist the wheels in gaining traction as they are rotated on low traction surfaces such as mud, ice, snow and the like.

Traction devices for application to the drive wheels of vehicles to assist in moving the vehicle when it is otherwise mired are known to the art and many patents exist on them. Some of these devices as depicted in the patents are of a simple wire-like construction as exemplified in U.S. Pat. Nos. 2,625,193 and 2,705,521; others are more complex and disclose special fastening means for securing the devices to the rim or tire of a vehicle such as in U.S. Pat. Nos. 2,664,934 and 2,625,194, which latter includes in addition to a special wheel rim and tire engaging clamp assembly a traction plate having a lug portion overlying the tread surface of a tire with teeth in the opposite surface for biting into the tread surface of the tire.

The present invention provides a novel traction device which is of improved construction so that it is rugged and durable in use while being readily adjustable to fit tires of varying width, which is provided with a unique and highly efficient traction plate structure to grip both tire tread and surface and which has a novel, simple, readily operable and easily managed shoe arrangement for securing or mounting the device on a tire.

The traction device of this invention comprises a pair of spaced apart traction plates adapted to overlie the tread or rolling surface of a vehicle tire joined at their ends by a pair of generally U-shaped radially inwardly extending tire side wall clamping or gripping elements, each having a bight portion and radially outwardly extending legs. To the free ends of the legs of each gripping element are connected the ends of the traction plates in a manner to permit fitting of the device to tires of different widths. Teeth on the plates project radially outwardly and inwardly therefrom for respectively engaging the tire engaging surface and engaging the tread surface of a tire to aid in preventing slippage of the device on the tire; a spring loaded arcuate shoe is swingably mounted on the bight portion of one of the gripping elements to aid mounting the device on a tire and in retaining the device in place on the tire when in use.

The invention is described in more detail in the accompanying drawings wherein:

FIG. 1 is a perspective view of a traction device embodying the invention;

FIG. 2 is a front view, partially in section of the device mounted on a tire;

FIG. 3 is a side view, partially in section of the device mounted on a tire.

FIG. 4 is a top view of one of the plates of the traction device;

FIG. 5 is a cross-sectional view of the plate taken substantially along the plane of section line 5--5 of FIG. 4;

FIG. 6 is a perspective view of a modified form of traction device embodying the invention; and

FIG. 7 is a cross-sectional view through the device of FIG. 6.

Turning now to the drawings in more detail, there is illustrated in FIG. 1 a traction device made in accordance with this invention designated in its entirety by numeral 10. The device comprises a pair of circumferentially spaced axially extending traction plates 12 which are adapted to overlie the tread surface of the tire. The plates are connected to one another by means of axially spaced generally U-shaped tire gripping elements 14 which are adapted to seat against the tire side walls. These elements 14 attach to the traction plates so that they can be moved toward and away from one another in adjusting the device to accommodate the width of the tire on which the device is to be mounted.

Each of the U-shaped gripping elements includes a bight portion 16 and radially outwardly extending diverging legs 18, the free end portions of which are axially inwardly turned to provide projecting arms 20 which are generally parallel to one another and overlie the end portions of the traction plates 12 to which they are firmly but adjustably fastened in a manner which will be hereinafter described. Stiffening bars 21 interconnect the legs 18 of each of the tire side wall gripping elements 14 adjacent the upper ends thereof just below the bend forming the inwardly projecting arms 20 to prevent the plates from spreading apart when in use. The bight portions 16 of the U-shaped gripping elements 14 are equipped with tire side wall engaging facing shoes. Shoe 22 is fixed to the bight of one of the elements 14 and is immobile. The other shoe 24 is fixed to the bight of the other element 14 by journal 25 and swings about the bight. The plates 12 slant away from one another and are not coplanar. The slant of the plates is generally tangential to the tire surface so that they follow the general curvature of the tire on which the device is mounted.

In FIGS. 2 and 3 the positioning of the traction device 10 on a vehicle tire 26 mounted on the rim of a wheel 28 can be readily observed. The U-shaped gripping elements 14 straddle the tire side walls with the facing shoes 22 and 24 tightly gripping the side walls just above the rim of the wheel. In these views, particularly that of FIG. 2, it can be seen that the shoes 22 and 24 are arcuate in shape, each forming a spiraling arc with the short radius at the connection of the shoe to the bight portion 16 extending inwardly toward the tire side wall with a gradually increasing radius curving away from the tire side wall toward the tip of the shoe as the shoe spirals outwardly away from the side wall 30 of the tire. Shoe 24 is spring loaded to bias the shoe toward the tire side wall by means of spring 32 attached at one end to the bight portion 16 of the gripping element 14 and having the other end attached to a suitable connection 34 attached to the inner surface of the shoe 24 somewhat beyond the point thereof where the shoe begins to curve away from the tire side wall; the spring biases the shoe normally axially inwardly from the bight portion 16.

To mount the device it is simply slipped over the tire with the traction plates spanning the tire tread surface and pressed radially inwardly until the traction plates 12 seat firmly against the tread or ground engaging surface 36 of the tire. As the device is pressed home, the shoe 24 is biased by its spring into engagement with the side wall of the tire, thereby holding the device firmly in place. Once in place, by virtue of its arcuate shape, the more radially outward force exerted in attempting to remove the device, the harder the shoe grips the tire side wall. However, to remove the device, the shoe 24 is simply swung axially outwardly against the spring bias away from the tire side wall and the device lifts easily off the tire.

The plates 12 by virtue of their angled relation to one another seat generally firmly against the peripheral tread surface 36 of the tire through the major portion of their width. As can be seen in any one of FIGS. 1, 2, 3 and 5, each of the plates 12 is generally T-shaped in cross section to provide a relatively long stem 36 with a cross-head 38 at one end thereof. The upper portion of the cross-head 38 comprises a toothed traction bar 40 projecting radially outwardly from the tread surface 36 of the tire to engage the surface of the mud, ice, slippery ground or the like against which the tire is pressed so as to bite into such surface to enable the tire to lower on the surface instead of simply rotationally slipping. The radially inwardly projecting portion of the cross-head 38 provides a toothed bar 42 for engaging the tread surface of the tire to prevent slipping of the device along the tire as the tire is rotated. The stem 36 of the T comprises a relatively broad plate of substantial thickness as it approaches the cross-head 38 but of gradually diminishing thickness as it approaches the outer edge or tip of the stem of the T. This shape aids in preventing gravel or the like from penetrating underneath the plate; it also enables wedging of the plate between the tire tread and the tread engaging surface to cause the toothed bar 40 of the plate to be in intimate engagement with the surface before applying power to the wheel.

Turning specifically to FIGS. 4 and 5 where the adjustability of the device to fit tires of differing widths is most clearly seen, it will be noted that the plate 12 is provided with a groove 44 in the upper surface thereof extending the length of the plate. In this groove the projecting arms 20 of the gripping elements 14 slide and are prevented by the side walls of the plate forming the groove from being laterally displaced. As is most readily observable in FIG. 4 the projecting arms 20 have elongated slots 46 therein so that these arms may slide toward and away from one another along plates 12 to adjust the width of the device 10 to fit tires of different widths. When the desired width is achieved, fastening means 48 connecting the arms of the gripping element 14 to the plates 12 are tightened down and the device is ready to be secured to a tire.

A somewhat different version of a traction device made in accordance with this invention is illustrated in FIGS. 6 and 7, the device being designated generally by the numeral 50 and comprising an adjustable traction plate construction rather than an adjustable gripping element construction as shown in the previously described version. In this version each traction plate 52 comprises a two-piece construction of lapping plates including an upper plate part 52A and a lower plate part 52B. The parts 52A and 52B are adjustable toward and away from one another to vary the length of the plate to adapt it to tread surfaces of different widths. This has the advantage of providing toothed plate coverage for substantially the entire tread width even on large width tires. However, the construction is somewhat more complex and not quite so easy to operate.

Toward its inner edge each plate part is provided with an elongated slot 54 and in that slot at regularly spaced intervals are teeth 56 part of which project radially outwardly to engage the surface on which the tire rides and part of which project radially inwardly to engage the tread surface of the tire. Each plate part likewise is provided with four holes 58. Adjustment is provided by placing one plate part over the other so that the teeth 56 of each plate part interdigitate with the teeth 56 of the other plate by projecting through the slot of the other plate part. By properly aligning the holes 58 with one another the plates can be moved relative to one another to span various tire widths. Upon proper placement the fastening means 60 are fastened into place to rigidify the two-part plate structure.

In the traction device 50 another variation is provided in that the reinforcing or stiffening bars 62 extend directly between the traction plates and attach at their ends to the plates rather than to the legs of the U-shaped gripping elements.

From the foregoing description it will be apparent that the invention is not confined to the specific constructions described and it is to be understood that the invention comprehends such changes in construction as may be permitted within the scope of the appended claims.