Juraj Rusnák

Study of tribological properties of chosen types of environmentally friendly oils in combined friction conditions.

This contribution describes the possibilities of using the ecological oils Mogul HEES 46, Hydros 46, Fuchs Plantohyd 46S and Shell Naturelle 46HF-E in a slide assembly. It compares their chosen properties reciprocally. A sliding pair was made up of a shaft from steel 14 220 and of a bearing shell. The bearing shell was fully of bronze, centrifugally moulded, with the trade mark B60 M4. The sliding pair worked during the whole experiment in combined friction conditions.

Influence of Bellows Setting on Its Spring Rate and on Temperature Adjustment of Electromechanical Thermostats

Abstract The precision and stability of adjusted temperatures are critical requirements for electromechanical thermostats. The key element in meeting the requirement is a thermostat bellows. It is a convertor of pressure into force that actuates the mechanical system of the thermostat. Convolutions enabling the axial movement of the bellows cause that the bellows is partly behaving as a spring. Therefore, the bellows has its own spring rate. The setting of the bellows spring rate influences the critical parameters of the thermostat. The aim of the article is to find the difference between the setting done by bellows producer and setting done by thermostat producer and its influence on the thermostat adjustment.

Effect of Selected Ecological Lubricants on the Wear of Defined Sliding Bearing

Abstract The presented contribution deals with the comparison of selected ecological oils of the same viscosity class in terms of wear of the sliding bearing B 60 M4 as part of the matched sliding pair lubricated by ecological lubricant. The wear of the sliding bearing is monitored using the parameters; the change of geometric tolerance cylindricity having the most indicative capability about the size and location of wear. The second parameter is weight loss, and the third parameter is the change of surface roughness at the contact point of friction elements. Results are statistically processed and presented in the form of graphs and tables.

Possibilities of using the ecological oil Arnica S 46 in agricultural engineering.

This paper deals with a possible use of biodegradable oil for lubrication of tribological nodes in hydraulic and transmission systems. They are mainly used in agriculture and forestry. For this reason, the research project was aimed mostly at hydraulic and gear oils, directly or indirectly designated for machinery working in these fields. The oil was tested according to the standard ASTM G77-05(2010). The study of the tribological node included monitoring the friction factor depending on time, and monitoring the temperature of the sliding node depending on time. In the triboelement shaft – bearing, we monitored the weight losses as well as changes in the selected characteristic of contact surface roughness. The monitored characteristic was Ra. A complete picture of geometric changes of the tested triboelement was described by the geometric deviation of cylindricity. The system also includes the study of lubricating medium. We determined the initial and final code of oil purity. The characteristics were statistically evaluated. Two oils were tested: PP 80 (producer: Slovnaft Bratislava) and ARNICA S 46 (producer: Agip). According to the results, both oils are appropriate for using in given conditions. No significant differences in their tribological characteristics were found. In conclusion, the results confirmed that the suggested system for evaluating the suitability of biodegradable lubricants is applicable in given laboratory or operating conditions. The conclusions can be used in practice for choosing the lubricant. The results can also help to create an order of appropriate oils. The conclusions can also be used by producers of lubricants as information about functional characteristics of their products.