Impact of the Chisel Edge on the Tillage Depth and the Plow Drawbar Resistance
The operation of a plow is associated with intensive wear of its working parts contacting with the soil mass featuring high wear capacity. Wearing and breaking down are typical for plowshares - parts undercutting soil layers. Plowshares are currently produced mainly with a face-mounted chisel. The authors have developed a new share of this type. (Research purpose) Determination of the influence of a chisel edge on the plowing depth and the plow drawbar resistance and making recommendations on the values of an optimal chisel edge for soil types of a loamy texture. (Materials and methods) Chisels have been designed to the share of plows with different edges relative to the frame blade. It has been proved that an edge interval between the chisel and the frame ranging from 15 to 70 millimeters is sufficient for field tests. On loamy soils, the depth of plowing increases as the chisel edge increases. It has been found that an increase in the chisel edge leads to an increase in the drawbar resistance of a plow. In the process of wearing, the penetration capacity of the plowshare decreases and the drawbar resistance decreases too. (Results and discussion) The authors have observed that when the chisel edge exceeds 70 mm on loamy soils, uncontrolled plow penetration occurs until the plowing unit deepens too much and stops due to the prevalence of the penetration force over the vertical component of drawbar resistance offered by the reaction of a support wheel. It has been noted that when the chisel edge (the distance between the chisel and the plowshare frame) increases to 35-45 mm, the drawbar resistance of the plow is reduced due to improved loosening of a soil layer by the chisel and decreased forces that cause soil pressure on the frame blade. The subsequent increase in the chisel edge contributes to an increase in drawbar due to increased dynamic loads caused by increased lumpiness, ridging and other factors. (Conclusions) It has been noted that for soil types of a loamy texture, an optimal chisel edge ranges between 35 and 45 millimeters with a cutting angle of 30-40 degrees.