of collisions, the docking mechanism has an extended buffer element which is retracted after linkage to connect the docking frames. Thus, the buffer is displaced in two cases: in shock absorption and in coupling (advancement). In the beginning or in the process of coupling the assemblies may be equalized, that is, coaxial. As a result the elements of the docking mechanism which are absorbing the shock, coupling and equalizing, are closely linked and interact. Tn collision one should provide for shock absorption for relative displacements of the spacecraft in any direction. Thus, the docking mechanism has, as a rule, several shock absorbers, and the buffer is displaced in all directions. This is true of various devices, “rod and cone” and peripheral. Three basic schemes of construction are possible for shock absorption-drive systems: 1) sequential, in which the shock absorbers deform relatively mobile elements of the drive (Soyuz docking device); 2) parallel, in which the drive, during coupling, deforms the shock absorbers (Gemini, Apollo docking devices, Apollo APDA); 3) combined, in which the buffer is linked to the drive through a slipping element, that is, the brake-coupling, which rotates with a certain force during shock absorption, and is used as a protective, limiting force for elements during coupling (Soyuz-Salyut docking device, Soyuz APDA). There are two basic types of latches: 1) independently guided latches; 2) latches controlled mechanically or by command. The second type of latch is more complex and its analysis must consider delay in closure and additional potential failures in the control elements. Their lower reliability is confirmed by the results of flight testing. Of great use is the experience acquired in the flight testing of the Apollo spacecraft. Several failures occurred in the operation of the docking mechanism, three latches of which were closed automatically when mechanical triggers were activated. Tn the redocking of Apollo-15 linkage did not occur in five attempts. On the sixth attempt, after contact, commander A. Shepard left the “longitudinal” engines of the jet control system switched on for —10 seconds, maintaining the command module and lunar module in contact, and turning on the drive of the docking mechanism, completely coupled the spacecraft until the locks of the docking frame were activated. However, after opening the hatches the astronauts observed that in the last attempt the latches worked, that is, the defect corrected itself. After analysis done on board and on Farth, the decision was made to continue the
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