Purpose. The article is aimed to carry out a structural analysis of the coupled straight-guiding crank-slide mechanism of variable structure gripping devices with external unilateral constraints. It is also necessary to determine the number of internal and external repeating connections in the contours of the mechanism at different stages of its functioning, to assess their possible perniciousness and to suggest ways to reduce them. Methodology. Achieving this goal is carried out based on the universal structural theory of Ozols mechanisms for analyzing the gripping device as a mechanism with geometric, internal and frictional holonomic external constraints. Ozols internal and external structural formulas are used. Findings. The eleven-link gripping device is built on the basis of coupled central parallelogram crank-slider mechanism with a driving cranks. Synchronous driving cranks act on elongated connecting rods connected to sliders and gripping clamp elements. Gripping clamp elements carry out plane-parallel movement. Structural analysis was performed using structural schemes for two states of the mechanism: before clamping the object and in the state of the clamped object. In the first state of the mechanism with kinematic pairs of class V, the one-movable scheme contains thirteen internal redundant constraints. In the second state of the mechanism, external constraints act and in the scheme another five additional external repeating constraints are formed. Their contour arrangement and possible consequences of their action are shown. Originality. Structural analysis of the coupled crank-slider mechanism of the gripping device as a mechanism of a variable structure with internal and external connections is carried out for the first time. It is performed contour analysis, search and elimination, as well as reduction of pernicious repeated connections in the internal and external contour of the mechanism. Practical value. Practical recommendations have been developed on changing the mobilities of sliding pairs to eliminate all repeated connections in the internal contours of the mechanism. To reduce the number of pernicious repeated connections, the introduction of a self-centering unloading coupling into the external contour of the mechanism is proposed.

Purpose. The main objective of the work is to perform a kinematic analysis and synthesis of the known schemes of guide bearing central slide-crank mechanisms by the criterion of the energy index of motion transmission with the restriction by the allowable pressure angles in the sliding pairs and the smallest deviation of the trajectory from straightness in the approximation area. The article is also aimed to determine the scheme that best suits the synthesis conditions and to propose the gripping device mechanism on its basis. Methodology. This purpose is achieved by means of analytical kinematics of flat mechanisms of the mechanism and machine theory and mathematical modeling of the positions and movement of links. Findings. The design of mechanisms with different gripping devices providing a constant clamping force of objects of various thicknesses with a constant drive power and minimal energy costs can be performed by the criterion energetic motion transfer index (EMTI). On its basis the analysis of the known straight-guiding central crank-slider mechanisms with an extended connecting rod is carried out according to the criterion of the smallest deviation from the EMTI unit. It was found that the practical use of main part of these mechanisms according to this criterion is extremely limited or impossible. Using optimized synthesis of kinematic equations, it was obtained the only values of the relative parameters and the rotation ranges of the driving crank for the guide bearing central slide-crank mechanisms with an extended connecting rod that best meet the optimization criterion and satisfy the restrictions for pressure angles. Based on the optimal parameters of the guide bearing central slide-crank mechanism a paired parallelogram eleven-link mechanism is proposed that provides the rectilinear movement of the gripping elements with a constant speed and constant clamping force which is equal to the nominal driving force of the drive. Originality. For the first time, a qualitative and quantitative analysis of the known schemes of the guide bearing central slide-crank mechanisms according to the criterion of the energetic motion transfer index was carried out and the optimal synthesis of the gripping device according to the results of the analysis was performed. Practical value. Practical recommendations are suggested for choosing a scheme, relative sizes and arrangement of links of the guide bearing central slide-crank mechanism of the gripping mechanism that corresponds to the requirements of the optimization criterion and restriction by the allowable pressure angles.

Purpose. The main purpose of the work is to carry out a kinematic synthesis of a crank-slider gripping device in accordance to the criterion of the constancy of the drive power of the mechanism with restrictions on permissible pressure angles in kinematic pairs. Methodology. Achieving this purpose is carried out by means of the theory of mechanisms and machines using the analytical method of the Ozols triangles of kinematics of plane rod mechanisms and mathematical modeling of the movement of links. Findings. The ten-bar mechanism of the gripping device is built on the basis of a paired parallelogram of a crank-slider mechanism with a leading slider. For gripping device, which is built on the basis of the rod scheme, it is advisable optimal design using the criteria for the transfer of motion or transmission indices. The criterion of optimization is the ratio of the speed of the leading link to the projection of the velocity vector of the driven point on the direction of the clamping force vector (power transmission index). The lowest energy costs can be achieved, provided that this ratio is equal to one. Analytical dependences are obtained for determining the velocity function of the central and de-axial crank-slider gripping device, which are convenient for analysis and modeling. On their basis, an energy synthesis of the geometrical parameters of the mechanism of the gripping device in accordance with the criterion of the smallest deviation from the unit ofpower transmission index is performed. The possibilities of the gripping device are enhanced by using it in a de-axial crank-slider mechanism, and the best results can be obtained in a scheme where the de-axial value is larger than the crank length. It is determined the specific values of the relative parameters of the lengths of the links and the ranges of rotation of the crank of the central and de-axial crank-slider of the grippingdevice, which best meet the optimization criterion and satisfy the pressure angle constraints. Originality. For the first time, a new criterion for the transmission of motion was introduced –power transmission index. According to this criteria, a kinematic synthesis of the gripping device built on the basis of a paired crank slider mechanism was carried out. Practical value. Practical recommendations are proposed on the size and location of the links of the mechanism for the central and de-axial crank-slider mechanism, which satisfy the requirements of the optimization criterion and implement restrictions on permissible pressure angles.