Oils Degradation in Agricultural Machinery

KUMBÁR VOJTĚCH, DOSTÁL PETR: Oils degradation in agricultural machinery. Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis, 2013, LXI, No. 5, pp. 1297–1303 Evaluating of oils condition in agricultural machinery is very important. With monitoring and evaluating we can prevent technical and economic losses. In this paper there were monitored the liquid lubricants taken from mobile thresher New Holland CX 860. Chemical and viscosity degradation of the lubricants were evaluated. Temperature dependence dynamic viscosity was observed in the range of temperature from −10 °C to 80 °C (for all oils). Considerable temperature dependence dynamic viscosity was found and demonstrated in case of all samples, which is in accordance with theoretical assumptions and literature data. Mathematical models were developed and tested. Temperature dependence dynamic viscosity was modeled using a polynomial 6th degree. The proposed models can be used for prediction of fl ow behavior of oils. oils, chemical degradation, viscosity degradation, modeling It should be noted that the motor oil is to be understood as one of the structural elements of the engine, transmission oil that must be understood as one of the components of the transmission and hydraulic oil is to be understood as one of the components of hydraulic system. The development of the new systems requires changes in the properties of lubricants. This change is necessary to increase performance and extend the lifetime of lubricants. Extending the lifetime of lubricants is an attractive customer advantage, which contributes to a reduction in vehicle operating costs. And it saves time of service. For large transport companies can be advantages know the lubricants level. Attention is focused mainly on the metal content and the lubricant viscosity and its stability. Many other operators makes analyzes only in cases of suspected abnormal operation. Sometimes it can be too late. In publication (Kumbár et al., 2011) is stated that the most of the friction surface is made of certain metals. It is a refi ned iron addition of other metals. There are the aluminum and copper parts. Or the parts with a surface layer of another metal. It aims to increase the surface hardness, improve sliding characteristics, and improve corrosion protection. We are therefore also interested in other metals than an iron. For example, aluminum, copper, chromium, lead, tin, nickel, silver. Other chemical elements in lubricant are oil additives. There are the detergents, friction modifi ers, viscosity modifi ers, anti-corrosive additives and antioxidants, substances that aff ect the freezing point, anti-abrasion additives, lubrication additives and some others with chemical elements: molybdenum, phosphorus, boron, calcium, zinc, magnesium (Meng and Huang, 2011). MATERIAL AND METHODS