The rod of the docking mechanism is a screw with a ball-screw converter which converts forward motion into rotational motion of the nut, and reverse conversion. Tn principle, the nut of the converter may serve as the forward support of the screw; however, when there are substantial lateral forces on the support, friction in the nut increases. When there is a shock on the cone, a force acts on the head, and there is a reaction in the forward support Wedging of the rod occurs for a significant ratio , which occurs in the extended position of the rod and small angles a, without consideration of the friction in the rear support, the reaction in which is substantially less, with a friction coefficient in the forward support For example, for , the condition of wedging . Thus, an additional forward contact support is installed (see Figure 3.6). To decrease the size, roller bearings are used without internal housings, and these have a large support capacity. Bearings in each pair of supports are displaced in the axial direction, which facilitates the work of the supports when there are screw grooves. Complete protection of the ball-screw converter, the heads, and other elements of the rod from foreign particles and contaminants is virtually impossible. In addition to constructive measures (redundancy, etc.) there must be careful preparation and monitoring during Earth-based preparation of the spacecraft up to final operations at the cosmodrome. The lining of the nut of the converter is installed in one four-groove ball bearing with a connecting internal or external ring. This bearing absorbs significant axial and radial forces, momenta relative to the transverse axes, and makes it possible to obtain a satisfactory force schematic for a small size and inertia of the rotating parts. The lateral forces are caused by bending of the switch, which may disrupt operation of the ball-screw converter. To avoid this, one must insure angular and radial displacements of the nut during screw deformations. It is very important to provide minimal inertia of the moving elements of the docking mechanism which move during shock absorption. This requires minimization
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