Efficient machining using the technology of wire electrical discharge machining (WEDM) is a compromise between cutting speed and surface quality. Typical morphology of WEDM processed surface features plenty of craters caused by electrospark discharges produced during the cutting process. The study deals with the evaluation of S-parameters enabling quantitative evaluation of the surface in all directions which are technically significant. Attention was also paid to surface morphology and its evaluation using 3D colour-filtered and unfiltered images. The experiment included 33 variants of setting machine parameters on samples made of two metallic materials: Al 99.5 and Ti-6Al-4V.

Helexa M., 2014. Monitoring the impact of tyre inflation pressure on tensile properties of forest tractors. Res. Agr. Eng., 60: 127-133.The article discusses monitoring of the impact of tyre inflation pressure on tensile properties of forest tractors. The LKT 81 T forest tractor, manufactured by ZŤS TEES, Martin (Slovak Republic) and widely used in Slovakia, was specifically chosen as the mechanised vehicle to be monitored. Tensile properties were examined using standard tensile tests, with a Tatra freight vehicle serving as the load vehicle. Actual measurements were performed on a concrete surface and on soil characterised as gravelly loam whose average moisture was 38%. The statistical methods used to verify the impact of significance from changes in tyre inflation pressure on selected tensile indicators were multi-factor analysis of variance (ANOVA) and Student's t-test. Even though statistical analysis failed to directly confirm significance in the impact of changes of tyre inflation pressure on selected load indicators for a forest tractor fitted with standard tyres, positive changes can be discerned in measured dependencies. The article concludes with a discussion of the results obtained and their possible application in operational practice.

Mikleš M., Helexa M., Mikleš J. (2017): Research on forest terrain roughness as a source of dynamic action on the vehicle. J. For. Sci., 63: 363-369.The issue of terrain conditions is very complex and its description is approached from different perspectives and with different objectives. Because it consists of the gathering of basic information for a mobile object, a wheeled forestry tractor, the terrain-vehicle approach was taken as the basis. Ground conditions are part of the operating conditions of wheeled forestry tractors. Uneven ground can be regarded as a source of vibration in the vehicle -towing truck. In this respect, given the random shape of the surface roughness, the solution to vibrations leads to a terrain correlation analysis in order to obtain a correlation function and power spectral density of the ground surface. Scanning of the ground micro-profile was performed using a device for quick terrain scanning, which from the mechanical aspect consists of a towing vehicle and a measuring carriage. Correlation function and power spectral density are the evaluation based on ground micro-profile measurements and the results of calculations. Measurements of forest terrain (road) micro-profile were done in the area of Little Fatra and Little Carpathians in Slovakia. In geological terms, the measurements were done in an area with the occurrence of gneiss, granite, limestone and flysch. No measurements were performed in a sandy area.

The article deals with measuring the rolling resistance of two tires Mitas TS04 6.00-16 6PR and Mitas TS05 10.0/75-15.3 10PR on a concrete surface. The measurement was performed in a soil test channel which had to be adjusted for the given purpose. The tires were compared with each other based on the results of the rolling resistance coefficient calculation. The obtained individual values were approximated by linear functions and subsequently subjected to a statistical analysis—a test of the agreement of the regression coefficients of the two basic sets. The results of this analysis showed that there is no statistically significant difference in the values of the achieved rolling resistance coefficients of the monitored tires, although there are differences between them in geometric dimensions and load capacity. The achieved results are basically confirmed by the results of other authors, especially by the fact that on a solid surface the values of the achieved rolling resistances can be reduced by increasing the inflation pressure of the tire. This increase cannot be spontaneous; however, it is always a compromise among the resistances achieved, the life of the tire and its adhesive properties.

The article focuses on the research of tyre rolling resistances in the soil test channel environment. The specific monitored tyre was a Mitas TS05 10.0/75-15.3 10PR diagonal tyre with an arrow tread. The measurement itself was divided into two stages. In the first stage, measurements of rolling resistance were performed on a solid concrete base of the laboratory in order to determine the internal component of rolling resistance of the tyre. In the second stage, rolling resistances were monitored on forest soil deposited in the main body of the soil channel. The mentioned measurements of rolling resistance can be considered key for further evaluation of traction and energy properties of tyres. Despite some complications which occurred during the measurement, the results obtained indicate the conclusions reached by other researchers in the field. The main conclusion of this research is to confirm the justification of using the correct or optimal level of inflation pressures of tyres of mobile energy means depending on the properties of the surfaces on which they move in order to reduce not only their energy intensity but also greater environmental acceptability.