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The article presents a universal multimicroprocessor on-board diagnostic system (UBDS) for on-road and off-road equipment. The UBDS allows to troubleshoot both auxiliary equipment, and control units of mobile machines. The structure of the hardware and the software, main characteristics of the system are given.

Modern hydromechanical transmissions are equipped with electronic-hydraulic (mechatronic) control systems having much more functional capabilities compared to classic hydraulic systems. However, automatic hydraulic systems are widely used not only as the basic transmissions' control device and a mechanical part of mechatronic systems but also as an important facility providing reliability and safety of such systems. At the same time such an application has quite a number of restrictions, especially for transmissions with a great number of gearstages. One of the main reasons is the inability to control more than 3 or 4 stages of gears while using the vehicle's speed as a control parameter. It deals with the parabolic characteristic of the output pressure of centrifugal governor used as the vehicle speed sensor. This restriction can be eliminated by using a hydraulic detector of torque converter's turbine (i.e. input shaft of gearbox) speed.

Comparative test have been run of rice-harvesters with wheel, metal-track and pneumatic-track propulsion systems. The pneumatic track was made in two versions: with air-filled elements (tracks), and with foam-filled ones. Tests were held on the concrete testing ground track and on the tilled field. Resistance to harvester's motion, resistance to turning round, pressure of propulsion systems on soil, soil deformation, and soil hardness in the rut (trace) were determined after harvester's pass. The investigations showed that soil deformation and hardness in the rut were minimum when the pneumatic propulsion system was used, and maximum when using the wheel propulsion system. Resistance to motion, on the other hand, was maximum with the pneumatic-track propulsion system, and minimum with the wheel one.

Speed measurement accuracy of computers installed on wheeled tractors, not equipped with radar velocity transducers depends on the following: the rolling radius of the wheel to which the speed sensor is connected; the number of sensor's pulses per revolution; and algorithms used for processing the data that arrives from the speed sensor. The work deals with the effect of static tire characteristics and other factors influencing the speed measurement accuracy of wheeled tractors by means of on-board computers. Recommendations are given aimed at accuracy improvement when measuring tractor speed.

Among important dynamic problems of the tractor-trailer unit are transverse vibrations of the trailer. The problem is so important because it concerns not only trailers of tractors, but also other units which can move quicker, and therefore, the vibrations can be very dangerous. The important task of this analysis was the estimation of the effects of parameter variations. This investigation showed that stability of the system is determined mostly by the damping of the coupling. The roots lines of the equations for many various dampings and velocities were therefore plotted. The optimum damping was found. At the end of this paper, as a result of investigation, the active control system was introduced. In the solution of this problem, the damping was changing according to the traveling speed. The block diagram of this follow-up control was presented.

Modern vehicles have a number of safety systems, main of which are basic control systems - steering and braking systems. Requirements to these systems, defined by the vehicles design safety, are regulated by the system of the international and national standards and rules. Mechatronic control systems of the hydromechanical transmissions pertain to the “yongest” automotive systems, and questions dealing with their safety don't have yet the complete theoretical and normative base. The connection between these mechatronic systems safety and their structure is investigated in this paper. The method of the safety analysis with help of the “refusal graphs” is proposed, which permits to bring out and to eliminate the possibility of the dangerous refusals capable to create the crash situations during automobile motion.

The problem of fuel consumption decrease in agricultural machinery may be addressed in several ways. One is to equip mobile agricultural machines (tractors, harvesters, sprayers, fertilizer spreaders, etc.) with on-board computers (BC) capable to measure the fuel flow rate, in particular, which will allow to decrease fuel consumption by these machines due to timely control of the technical conditions of the engine and optimization of the machine operation modes from the point of view of fuel consumption. The article describes a family of diaphragm chamber fuel flow transducers (FFT) for on-board computers of mobile agricultural machines, gives their technical characteristics and laboratory and field test results, and recommendations on connecting them to engines of various power specifications.

Traction systems for agricultural vehicles compact soil much more than the optimal density for crop yield. For this reason crop yields decrease both in the season in which compaction occurs and in subsequent years. That is why the soil compaction problem may be considered an ecological one. Among the well-known traction systems used to decrease soil compaction are; decrease of air pressure in tires, dual wheels, multi-axle wheel and crawler traction systems, improvement of tire deformation properties, etc. However, the analysis performed revealed contradictory results of using the above ways under varying operating conditions. Thus, it is not clear at what soil conditions it is appropriate to apply dual wheels, multi-axle wheel traction systems, or special appliances to increase the propulsion system's contact surface and thereby decrease its compaction. Different traction systems have varying effects on compaction for arable and sub-arable soil layers.

The effect agricultural machinery traffic on soil is minimized in various ways. Some of these techniques are very effective. By creating various designs of traction systems and by using rational parameters, it is possible to attain substantial improvement of operational properties with agricultural machinery. It is possible to increase the mobility and tractive efficiency, to decrease the soil compaction, fuel consumption, etc. This paper will show the operating conditions of tractors and agricultural machinery in Belarus and the requirements for traction systems at various periods of operation. It will also show the experience of creating and developing designs of track and half-track (rubber belted) propulsion systems for tractors and other agricultural vehicles. Such designs have been created for 60 kW tractors, harvesters and other machines. Quickly removable designs of wheel-track systems are proposed.

According to the tractor theory, the operating mass of a tractor is calculated from its traction force required to overcome the resistance of soil-cultivating implements and provisional incidental overloads. Implements' resistance changes are estimated by the coefficient of possible overload -- the ratio of maximum possible resistance to its average value, i. e. the maximum resistance value of the implement is used for calculations One of the regulating agricultural operations in the choice of tractor's operating mass is plowing. Besides, the implement's resistance change with the speed increase of the tractor's aggregate is not taken into account. The operating tractor's mass calculated by this method is by 10…20% different from the optimum operating mass.