In order to optimize the design and working parameters of agricultural machinery related to harvesting, knowledge about the physical properties and mechanical behaviour of harvest-ready maize is required. Previous studies have been conducted on different maize varieties from different parts of the world in different growing seasons. However, these experiments were usually conducted on dried or deep-frozen samples and therefore the condition of these samples was not related to the harvested material. In order to produce more relevant experimental results, a complex measurement method that involves in-situ observations and laboratorial experiments was established after taking into consideration the process of maize harvesting with a combine harvester and a maize header. The measurement method was successfully conducted over a period of days of harvesting in Hungary. With regard to the physical properties of the stalk, the distribution of the internodal diameter and the length, mass and moisture content of the stalk were determined. The mechanical behaviour of the stalk was analysed through transversal compression, three-point bending and dynamic cutting experiments. The results clearly demonstrate that the physical properties (diameter, length and wet-mass ratio, moisture content) and mechanical properties (force response characteristic and required mechanical work) of different parts of the maize stalk vary significantly. Therefore, different parts of the maize stalk require different considerations during machine development. K e y w o r d s: maize stalk, measurement method, mechanical behaviour, physical properties

One of the most common methods to measure soil strength in-situ is cone penetrometers. In this paper the development of a three dimensional (3D) discrete element model (DEM) for the simulation of the soil-cone penetrometer interaction in a slightly cohesive loamy sand soil is presented. The aim was to investigate the effects of the soil model's geometrical (e.g., soil model cross section shape and size and model's height) changes on variations in the soil penetration resistance. The model area ratio and height ratio values were adopted to analyse the effects of the cross section size and the model's height, respectively. The results of penetration resistance of the DEM simulations were compared with the in-situ measurement with a cone penetrometer of the same geometry. This comparison allowed the derivation of the contact properties between the elements. To simulate the soil material the so-called Parallel Bond and Linear Models were used in the 3D version of the Particle Flow Code (PFC) software. Finally the mechanical properties of the soil, namely the cohesion and internal friction angle were estimated by DEM simulation of direct shear box. Results showed that the penetration process can be simulated very well using the DEM. The model's calculated penetration resistance and the corresponding in-situ measurement were in good agreement, with mean error of 14.74 %. The best performing models were a rectangular model with an area ratio of 72 and a height ratio of 1.33 and a circular model with an area ratio of 32 and a height ratio of 2. The simulation output of soil material properties with direct shear box resulted in representative values of real loamy sand soils, with cohesion values range of 6.61-8.66 kPa and internal friction angle values range of 41.34-41.60°. It can be concluded that the DEM can

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Since late 1995, when the high-powered (194 kW) Fendt Favorit 926 equipped with a "Vario" transmission was launched, power machines with CVT (Continuously Variable Transmission) have appeared on the palette of all major tractor manufacturing companies as well. The CVT unit in the transmission of these power machines is not included directly in the power flow, but in one of the power branches after a split. By modifying the gear ratio of a properly selected CVT unit, the transmission can be geared neutral and the direction of progress of the vehicle can be changed. The transmission structure produced so is called power split IVT (Infinitely Variable Transmission).The paper presents the ways of producing an IVT drive and analyzes the Fendt "Vario" driving mechanism with OC-RSC structure and the same elements but with IC-RSC structure. There is detailed analysis on both structures on power flows (power split, positive/negative power circulating), the Geared Neutral and the backward operational stages, taking into account the significant states from efficiency calculation point of view, together with changes thereof in function of output revolution. Based on these investigations it is highlighted that the entire range of the course of the vehicle can be covered by an output coupled system adjusting the gear of the CVT unit within the high-efficiency range. The task is the same for input coupled systems, to be realized by planetary gears installed after the IVT unit and by the proper control of their engagement. gyetem rkp.3, HungaryPower flows and efficiency analysis of out-and input coupled IVT Per. Pol. Mech. Eng.

This study focuses on the adaptability of discrete element method (DEM) in agricultural machine design.Laboratorial three point bending, compression and dynamic cutting tests were conducted to define the main mechanical parameters and behaviour of corn stalks.For the DEM simulations of the laboratorial tests Timoshenkobeam bonded model was selected. With modifications of the geometry structure and the input parameters of the contact model, during an iteration process, the right assembly was found.The findings of the study clearly demonstrate that DEM capable of simulating the interactions, among the plants, the parts of the machine, and the appeared loads during agricultural processes.