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Efficiency increase of an agricultural tractor may be achieved through installation of a pneumatic track propulsion system to combine the benefits of both pneumatic wheels and rubber tracks. A pneumatic track comprises a power belt and a number of pneumatic elements attached thereto. Serviceability of the pneumatic track is dependent upon the properties of its pneumatic elements. The article gives the methodology and static test results of several types and dimensions of pneumatic elements. The tests were run on a custom-designed testing stand. Geometric parameters, properties of static rigidity rate (normal, lateral, and tangential), and pressure distribution coefficient versus air pressure in the pneumatic elements have been determined. Through mathematical processing of experimental data regressional equations have been obtained. The methodology and the results of the experimental studies are given for a tractor having a pneumatic track propeller.

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).

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.