Because work machines often operate in harsh environments and are continuously cycling through no load and relatively heavy loads, work machine tires must be durable and not susceptible to flats. In fact, it has been found that although conventional pneumatic tires provide a smooth ride, pneumatic tires often are less durable than solid tires. However solid tires are known to provide a less than smooth ride.
In order to provide sufficient durability, work machine tires can be non-pneumatic, and thus, are comprised of solid or semi-solid products. Although the non-pneumatic work machine tires are more durable than pneumatic tires, the non-pneumatic tires are often too stiff to provide a smooth ride and lack the contact area with the ground to provide relatively good traction. In order to improve the ride of the work machine, some non-pneumatic tires include a radial band of unpressurized cavities, or recesses. The radial band lessens the stiffness and increases the deformation of the tire so it will ride better than a solid tire. Such a tire is sold by MITL under a trademark that suggests flexibility, but it still provides a stiff ride more similar to a solid tire than a pneumatic tire.
In another example, the non-pneumatic tire described in U.S. Pat. No. 5,042,544, issued to Dehasse, on Aug. 27, 1991, defined a radial band of recesses that enable the tire to deform due to a load and provides an area of contact with the road that is supposedly similar to that provided by a pneumatic tire. Further, in order to better control the deformability of the tire and to limit the collapse of the recesses, the recesses of the Dehasse non-pneumatic tire are taught as being intrinsically dissymmetrical to any radial direction and overlap one another. Although the Dehasse non-pneumatic tire uses recesses in order to control the tire performance and road handling, the Dehasse tire is intended to have a weight and bulk similar to that of pneumatic tires. Thus, the Dehasse tire would not possess the durability required for high load, low speed work machine applications.
Work machine tires are also subjected to tangential forces, such as braking and traction forces, and widely varying radial forces associated with payload. A single radial band of cavities, especially those that are angled, would exhibit unequal clockwise and counterclockwise torsional stiffness. In addition, they would have the tendency to rotate the outer portion of the tire relative to the hub as radial load is varied. This torsional stiffness bias could result in undesirable and unpredictable work machine motion.
The present disclosure is directed at overcoming one or more of the problems set forth above.