Lucretia Popa

An important operational indicator of agricultural machine-tractor units is the smoothness of movement, which significantly affects the traction and dynamic performance of their work, productivity, agronomic qualities of the operation, traffic safety, durability and efficiency. As a rule, it is evaluated by the influence of oscillations (translational vertical, transverse, angular longitudinal, etc.), on these indicators, as well as on the physical condition and health of operators who control these units in real production conditions. This article presents an improved method and results of experimental assessment of the smoothness of the movement of the modular agricultural unit, which moves in the footsteps of a constant technological track. Studies of the smoothness of the modular unit showed that the graphs of normalized correlation functions of vertical oscillations of the modular agricultural tool developed by us in its motion in the wake of a constant techno-logical track is characterized by a function containing along with random components harmonic, which are expressed by attenuating periodic oscillations. The range of frequencies of oscillations of the frame of the agricultural tool is concentrated in the range from 0 tо 20 s−1, which is consistent with the frequency range 0…0.3 s−1 in which the variances of oscillations of inequalities of a profile of traces of a technological track are concentrated. Studies have confirmed the effectiveness of the method of estimating the intensity of vertical oscillations of the agricultural unit measuring and recording system based on a tablet computer with Android operating system with built-in accelerometer sensors and Accelerometer Meter application. The developed technique of mathematical modelling and experimental determination of vertical oscillations of the machine-tractor unit can be used in the study of the dynamics of other agricultural machines and units.

This article presents the results obtained through experimental research carried out with a machine for shredding woody plant residues (twigs, vine ropes), residues obtained from dry or green cuttings, in fruit or wine plantations. The obtained shredding is intended for utilization in the form of compost or biofuel (pellet type). The machine was designed and made by a group of researchers from INMA Bucharest, with the aim of developing the machine system made available to farmers, for mechanized work in small and medium-sized fruit plantations. The sizes of the fractions of the wood fragments resulting from the chopping process, their humidity and volumetric weight were determined. Using as raw material greener or drier branches, with dimensions between 10-45 mm, with an adjustment of the chopping drum at an average speed of 1400 rpm and an average speed of the conveyor chain of 0.425 m/s, wood chips with different sizes between 4 and 16 mm were obtained, the proportions varying from 13% to 16%. The average working capacity of the equipment was approx. 14.2 mc/h. Research will continue to determine the energy indices of the machine designed and made at INMA Bucharest, and the results will be presented in another article.

In a paper previously published by the authors, kinematic analysis of a jack mechanism driven by a motor tetrad was done. For the actual design of the mechanism, the forces and moments acting on the kinematic elements that are part of it must be determined. Also, the driving force in the hydraulic cylinder must be determined, so that the mechanism works in good conditions, for a certain technological task imposed by the design theme. The present paper makes the kinetostatic analysis of the mechanism studied, from the kinematic point of view. Therefore, the reactions in the kinematic couplings of the mechanism, as well as the driving force of the hydraulic cylinder, are determined. In order to determine the reactions of the kinematic couplings, as well as the driving force of the hydraulic cylinder, the masses of the elements, the moments of mechanical inertia, as well as the load force acting on the jack were considered. The results of the calculations were graphically represented, in reaction patterns. In order to verify the correctness of the calculations, the balance force (the hydraulic cylinder motor force) was determined by both the kinetic and the virtual power method, and the results are the same.

Organic fertilization involves working with machines by a special construction, suitable for the material to be spread, machines that have, in most cases, chain conveyors with scrapers attached to the chains. In some cases, the conveyor chain may break, due to the jams, and the need for manual unloading of the bunker (bucket) appears, which requires a great physical effort, the unloading being made by the operator, using a shovel. The construction of the platform using mobile, articulated elements would greatly facilitate the unloading at the bottom of the bunker and would eliminate the physical effort of the operator. This article presents the structural, kinematic and kinetostatic analysis of a mechanism designed for actuating a mobile platform, which is part of a manure spreader, composed of articulated elements driven by hydraulic cylinders.For the kinematic analysis of the mobile element platform’s mechanism, calculation procedures written in the Matlab syntax are used.After the kinematic analysis of the mechanism, the kinetostatic analysis is performed, i.e. the determination of the reactions from the kinematic couplings, as well as the hydraulic force from the hydraulic cylinder. The results can be used for dimensional verification of the mechanism components, thus contributing to the optimization of the mechanism.

The bodies of trucks or trailers are provided with automatic folding shutters to ease the discharge of the transported materials. Typically, these shutters are powered by mechanisms that have active motor groups such as RRTaR or RR-RR-RTaR (i.e. motor dice or triads) and passive motor groups such as RRR, RR-RR-RR etc. If the technological forces are high and the relative speeds between the elements forming the steering coupler are small, the motor groups are formed by rigid bars and hydraulic cylinders. If relatively high gear ratios are required, then pneumatic cylinders may be used. If required relatively high speeds in the driving couplings, then you can use pneumatic cylinders. This paper presents structural and kinematic analysis of a shutter from a trailer used to transport bulk agricultural products, discharge towards the back. For the kinematic analysis of the folding shutter mechanism, computational procedures written in the Matlab syntax are used. The results of the calculations are presented in tabular and diagrams. After the cinematic analysis of the mechanism, it is possible to perform its cinetostatic analysis, i.e. the determination of the reactions from the kinematic couplers, as well as the hydraulic force in the hydraulic cylinder. Results can be used for the dimensional verification of the chosen elements.