As a result of the analysis of the work process of a safety device mechanism a mathematical model was for mulated. It was a model of a dynamic force F_x protecting a cultivating tool from overload and realized by safety device mechanism. The selected sort of the safety device mechanism was based on a spring-loaded accumulator (with a single screw spring) using kinematics of a four-bar linkage with a second-class lever. It can be used both to protect working elements and for central protection of cultivating tools. On the strength of the model it was found that an overload force F_x – brought to resistance horizontal component appliced at a share point of a cultivating tool – occured as a function of 24 different (specified in the article) parameters of work process of the cultivating tool protected in that way. The parameters can be assigned to two subsets: to constructional parameters (defined – regarding the value – univocally by the construction) and using parameters (whose values follow from using conditions) of the cultivating tool. Some formulae for computer simulation of these parameters’ influence on the value of a force F_x were given.

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