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The main requirements to which the brake system of a vehicle should respond are provision of the standard operation speed and protection features of the control pneumatic drive in case of a malfunction of any of its elements. The article describes a design of modified pneumatic brake drive having improved protection properties in case of damage of a diaphragm of any brake chambers, and methodology of parameter optimization of such drive allowing to create a layout of drive assemblies with the necessary operation speed for MAZ truck-based road trains.

One of major requirements produced to fuel flow transducers installed on mobile agricultural machines with diesel engines is minimum resistance to fuel flow passing through them in order not to exert any influence on operation of the engine. The paper gives a mathematical model of a diaphragm chamber fuel flow transducer, description thereof may be found in SAE paper No. 982048 [1]. Optimization results of the mathematical model of the transducer's design parameters are given.

A perspective design technique of on-board computers for mobile agricultural machines is their creation on the basis of standard modules allowing to reduce the designing period, to improve reliability, quality, and also to make operation and modernization of designed systems cheaper. Because modules are made in different standards, there is a problem of choice of modules for a concrete application. The paper considers various problems of application of a PCI bus in on-board computers of mobile agricultural machines. Recommendations on efficient use of the PCI bus are given.

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.

Distribution of traction forces among driving wheels is one of the main factors governing the performance of a highway truck during acceleration and braking on varying macro and micro road surface conditions. Comprehension of the interaction between wheels and road surface provides a profound systematic way to simulate a truck's motion and design required components for the optimal performance. The development of electronic technologies has created the pre-conditions necessary to develop systems with controlled parameters. However, to realize the pre-conditions, vehicle dynamics problems have to be formulated and solved for both optimization and control. Many different approaches emerged with the aid of electronics to control the circumferential wheel forces (wheel torque) by restricting wheel slip. A part of such systems has been named as Acceleration Slip Regulation (ASR) and Anti Slip Differentials (ASD).

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.