International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Forests tractors are inseparable part of a forest economy. Forests tractors serve for logging of logs in forests. Current forests tractors are usually equipped by hydraulic arms, which allow to expand the utility of a tractor. A tractor with a hydraulic arm is able to handle with wood logs without a need additional forest machine, which helps to reduce costs. On the other hand, it is necessary to analyse tractors abilities, which has such an additional equipment. This article is focused on assessment of stability of a forest tractor, which is equipped by such a hydraulic arm. It is a newly designed forest tractor which smaller dimensions, which is intended to be used in conditions with requirements for lower contact pressure and better manoeuvrability. As the hydraulic arm changes the centre of gravity of an entire tractor, mainly with the load, safe operation of the tractor needs to know limit conditions of stability under the maximal load and in the given slope inclination.

The paper is a continuation of research dealing with the structural design of the manipulator of the bulk material rotary valve based on the specifications of a food company. This issue is currently immensely topical for reasons such as increasing safety, speed, or efficiency of work. In the previous publication, the authors focused on determining the position of the center of gravity of the rotary valve due to the fact that this essential data is not provided by its manufacturer. Accordingly, the present work attends to the design of the steel structure of the trolley and the path along which the trolley in conjunction with rotary valve will move. The structural design is analyzed in the paper by means of analytical functional and dimensional calculations. On the basis of the parameters of the calculated centers of gravity of the individual components of the structure, the reactions from the track on which trolley travels to the weight transmitted by the prismatic wheels of the trolley were determined. The loads were calculated in transverse and longitudinal directions. In addition, reactions from the individual wheels were determined for the case, when the rotor valve is in a position with the rotor retracted (operating position). The achieved results demonstrate that the least favorable case for the stresses on the track travel of trolley occurs in the case with the rotor retracted. Furthermore, the calculation of the loads acting on the track beam in the most unfavorable position of the trolley was performed. Moreover, the resistive forces acting on the trolley were analyzed. The results indicate that the use of this mechanism will be feasible in operation.