Changes in the External Speed Characteristics of Chainsaw Engines with the Use of Mineral and Vegetable Oils

Nacrtak Similarly to many other countries, the use of biologically degradable oils in forestry is also addressed by the Czech law. Several studies point out several technical problems regarding such regulations. It has not been demonstrated so far whether for example biologically degradable engine oils used for chain saw lubrication from mixture may be the cause of an excessive engine wear or deterioration of the combustion process and hence increased contamination of air inhaled by the operator. An experimental laboratory measurement was taken for the purpose of determining the external characteristics of a common chain saw engine at a brake stand, which enabled exact measurement of differences in engine output, fuel consumption and composition of exhaust gases (CO, CO2, and HC), namely in dependence on the type of oil and the blending ratio. The results of the laboratory tests did not reveal any statistically significant differences between the oils in any of the measured criteria. The theory of workers based on practical experience that some oils may cause clogging of the fine fuel filter in the carburettor and that increased carbon sedimentation occurs in the engine exhaust duct was neither displaced by evidence, nor corroborated. Its refutation or confirmation would only be possible on the basis of a longer service test.