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Gear drives are widely used in various fields and applications due to their properties and capacity. Their versatility, durability, and ability to transmit high torques as well as precision and reliability make them extremely useful in many fields of technology. They are widely used in industrial and energy machinery, vehicle drive systems, aerospace, medical devices, and many other areas. Gears can be manufactured using many technologies. This work focuses mainly on machining with particular emphasis on high-performance new technologies. The process of mathematical modeling of the gear and the machined profile is strongly related to CNC machining technologies. A robust correlation of systems supporting the design and modeling of sliding gears needed for the manufacturing process is presented in the article. It is very important to properly assess gears with correct manufacturing in accordance with a specific standard. The article presents an analysis of available methods for controlling gears using coordinate measurement techniques. Gear machining methods were assessed in terms of the technologies used as well as their productivity and manufacturing tolerance. [ABSTRACT FROM AUTHOR]

Understanding the soil-plant relationship is important to determine critical limits of soil properties that influence crop growth and yield. The objectives were to quantify the influence of soil compaction levels on physical properties and crop growth and yield in a clayey Oxisol. An experiment was performed having in the main plots, levels of soil compaction (NT: no-tillage during six years, NTC: NT + four passes of a 10 Mg machine in the agricultural year 2003/2004, and Chisel: NT + chiseling and harrowing in the agricultural year 2003/2004), and in the sub-plots, the summer crops soybean and corn, and wheat in the winter season. We measured soil physical and mechanical properties, along with yield of corn, soybean and wheat, and root growth of that last two crops. After four passes of a 10 Mg machine, the soil resistance to penetration increased to a 0.12 m depth, while Chisel disrupted the 0–0.20 m soil layer, with the effects persisting for at least nine months. Soil compaction in no-tillage concentrated in the 0.05–0.15 m layer. Corn yield was similar among the treatments, soybean yield was highest in NT, and the highest yield of wheat was in the sequence with soybean under NT. [ABSTRACT FROM AUTHOR]

Soil compaction is a worldwide problem in agricultural areas, and it is important to define soil properties and reference values that allow knowledge of the compaction level for decision making. The objective of this study was to define the critical values of physical properties associated with the compaction of soils. Three Ultisols and two Oxisols, under different management systems, were collected at different depths for an evaluation of particle size, volumetric moisture, bulk density, and porosity. In the field, soil resistance to penetration and the root length of the soybean and edible black bean crop were measured. The soil profiles presented horizontal layers with similar resistance, but in some cases, there is discontinuity of these layers, which allows the roots to use the zones of lower resistance to deepen in the profile. The values of bulk density and resistance to penetration critical to soybean and edible black bean (only in sandy loam soil) root growth, according to soil textural class, are: sandy loam = 1.66 Mg m−3 and 1.5 to 2 MPa; loam and clay loam = 1.52 Mg m−3 and 1 to 1.5 MPa; silty clay loam and silty clay = 1.32 Mg m−3 and 1.5 to 2 MPa; and clay = 1.33 to 1.36 Mg m−3 and 2 to 3.5 MPa. [ABSTRACT FROM AUTHOR]