Agricultural and transport equipment is ideally suited to use hydraulic oils. After engine oils, hydraulic fluids are the second most important group of lubricants. More than 85 % of these materials are currently mineral oil-based. In view of their high ecotoxicity and low biodegradability, mineral oil-based lubricants constitute a considerable threat to the environment. In contrast, most hydraulic fluids based on plant oils have a low environmental impact and are completely biodegradable. Moreover, lubricants based on plant oils display excellent tribological properties and generally have very high viscosity indices and flash points. For this reason, therefore, particularly soybean, sunflower and rapeseed seem to possess the relevant properties as a potential hydraulic fluid. There are several tribotechnical methods how to assess the current technical state of used lubricants (viscosity, water content, flash point, acidity). One of the modern methods how to detect wear particles is LaserNet Fines, which is a suitable technique for machine condition monitoring. The ageing of test oils is analysed by the Fourier transform infrared spectroscopy (FT-IR); for determining anti-wear properties of hydraulic oils, the standard STN EN ISO 20623:2004 indicates 1 hour under an applied load of 150 N. The objective of the paper is to show the description and examples of modern tribotechnical methods used for determination of the technical state of used biolubricants utilized in agriculture and transport machinery.

Article citation info: Introduction and literature surveyMany maintenance strategies, policies and methods have been developed, which are aimed at making maintenance cheaper and more effective. Such programs have the minimization of costs, downtime and losses due to failure of critical objects of the equipment as their main objective. Cost minimization improves the effectiveness and profitability of the organization [1,2,9,12,13,20].For creation of the maintenance policies, well described data mining input is very important. [4].In recent years, useful models of preventive and predictive maintenance optimization with different complexity and applicability have been further developed.In the paper, [5] the authors proposed a quasi-periodic imperfect preventive maintenance policy. Finally, a real case study of preventive maintenance on Chinese diesel locomotives is examined to illustrate the proposed maintenance policy.The paper [6] proposes an approach in which preventive and failure replacement costs as well as inspection cost are taken into account to determine the optimal replacement policy and an age-based inspection scheme, such that the total average costs of replacements and inspections is minimized.Determination of the preventive effect of optimal replacement policies in the paper [8] is based on aging intensity and the cost ratio of failure and preventive replacements. One of its conclusions is that not every preventive maintenance is fully effective and a policy of, "run to failure" can be more effective (note: in some cases).The proposed model in the paper [10] takes into consideration the stochastic nature of equipment failures. The output from the model is a cost distribution against the time from which the minimum cost may be found for a particular period and this period is defined as the optimum lifespan of the machine part.The paper [11] considers periodic preventive maintenance policies for a deteriorating repairable system. On each failure, the system is repaired and, at the planned times, it is periodically maintained to improve its performance reliability. Most periodic preventive maintenance (PM) models for repairable systems have been studied assuming that the failure process between two PMs follows the nonhomogeneous Poisson process (NHPP), implying the minimal repair on each failure.The paper [14] regarding warranty policy considering three maintenance options for products with multiple failure modes also showed the broad usability of the Weibull distribution. This fact supports the decision of the authors to also use the Weibull function.The paper [15] presents a new mathematical function to model an improvement based on the ratio of maintenance and repair costs, and demonstrate how it outperforms fixed improvement factor models by analyzing the effectiveness in terms of cost and reliability of a system. Legát V, MošnA F, ALeš Z, JurčA V. Preventive maintenance models -higher operational reliability. eksploatacja i niezawodnosc - Maintenance and reliability 2017; 19 (1): 134-141, http://dx...

The aim of the study was the examination of the morphological and compositional attributes of wear particles of tested universal tractor transmission oil (UTTO) samples by means of automatic particle counter and classifier LaserNetFines TM -C, which is an ideal tool to establish the dynamic equilibrium concentration and hence to set the alarm limits for any type of machine. Such limits can be based on wear type and particle size ranges. The samples of two UTTO (mineral oil and biodegradable fully synthetic oil) were taken from the rear gearboxes of the wheel tractor during a long-term experiment. The measurement results showed that there was faster increase in the particle wear of mineral oil in comparison to biodegradable transmission oil. Considering the increase in the percentage of particles over 20 μm, the biodegradable oil seems to be more favourable for usage. Regardless of this, it can be concluded that the biodegradable oil is equivalent to petroleum-based oils.

Methodology of overall equipMent effectiveness calculation in the context of industry 4.0 environMent Metodologia obliczania ogólnej efektywności sprzętu w kontekście środowiska industry 4.0 Industry 4.0 and related Maintenance 4.0 demand higher requirement for productivity and maintenance effectiveness. Nakajim's OEE indicator still plays an important role in measuring effectiveness of production and maintenance. In connection with the current Industry 4.0 challenge, the issue of Industrial Internet of Things (IIoT) is highly accentuated. This topic includes the matter of autonomous management and communication of individual machines and equipment within higher and more complex production units. Authors propose original calculations OEE for the whole production line from OEE knowledge and individual machines, including knowledge of their nominal and actual performance. The presented solution allows a greater depth of analysis of machine efficiency and overall effectiveness calculation of different assembled production lines based on knowledge of individual machines efficiencies.

The global concentration of greenhouse gasses in the atmosphere is increasing as well as the emissions of harmful pollutants. Utilization of liquid biofuels in combustion engines helps to reduce these negative effects. For diesel engines, the most common alternative fuels are based on vegetable oils. Blending neat vegetable oils with diesel and/or alcohol fuels is a simple way to make them suitable for diesel engines. In this study, coconut oil was used in ternary fuel blends with diesel and butanol. Coconut oil is a potentially usable source of renewable energy, especially in the Pacific, where it is a local product. Diesel fuel-coconut oil-butanol fuel blends were used in concentrations of 70%/20%/10% and 60%/20%/20%, and 100% diesel fuel was used as a reference. The effect of the fuel blends on the production of harmful emissions, engine smoke, performance parameters, fuel consumption and solid particles production was monitored during the measurement. The engine was kept at a constant speed during the measurement and the load was selected at 50%, 75% and 100%. From the results, it can be stated that in comparison with diesel fuel, specific fuel consumption increased with a positive effect on the reduction of engine smoke.