Graphic analytical optimization of design and operating parameters of tires for drive wheels of agricultural machinery

Abstract

Historically, machinery with wheels and tires has dominated the agricultural machinery market, despite the rapidly growing popularity of rubber tracks. However, notwithstanding the rather long development history of wheels, unresolved problems remain. Most of these are associated with a reduction in the harmful effects on the soil. The aim of this study was to reduce the levels of load on agricultural soils by the drive wheels of agricultural machinery through optimization of the geometric dimensions of the flat and deformed soil surface contact areas of an elastic wheeled vehicle. The tire used for agricultural machinery was modeled mathematically, principally using the properties of Cassinian curves. Some tire dimensions and materials do not satisfy the folding condition, which specifies that the ratio of distances used in specifying Cassinian ovals, a/c, should not exceed 1.41. Based on the geometric definition of a Cassinian oval, the shape of the contact profile surface of an elastic tire–soil interaction is determined by the ratio a/c. Different a/c ratios correspond to different tire shapes. When a/c = 1.2, the profile shape of the undertread of the tire does not satisfy the folding condition. Using the geometric properties of a common circle and Cassinian ovals, it was possible to determine a value of angle α≈48°. This angle is optimal for the tire–soil contact surface and, also satisfies the without folding condition. The presented method may be applicable to bias-ply and radial-ply tires, so it is not specifically applicable for one of these over the other.