disengagement, each pair of latches is released by an electrical drive which is turned by an eccentric mechanism. For redundancy in disengagement, all three pairs of latches may be fired with pyrotechnics. The casings of the latches, which are held back by the turning of the pyrotechnic bolts, are turned and leave the latch with its supports. The redundant disengagement mechanism acts independently of the main one. For disengagement, in principle, it is sufficient to release two pairs of latches of the three. For disengagement from A PDAs in the passive position the catches of the latches are equipped with mechanisms to release them. Fach catch contains an electrical drive to rotate the eccentric mechanism, which releases the catch for rotation and releases the connection with the latches of the Apollo. Docking mechanism of the Apollo APDA. The ring with guide protrusions of this docking mechanism is installed on six independent spring-hydraulic shock absorbers [40]. When hydraulic shock absorbers are used, the use of hydraulic or pneumatic drives is required to move the ring. Actually this scheme was examined in the initial stage of planning. The hydraulic-pneumatic drive is supplied from two (for redundancy) tanks of highly-pressurized nitrogen. The development of this scheme was very technically difficult, and required the use of a large number of elements . Thus, this variant of the device was not further developed. Tn the scheme that was adopted, with independent shock absorbers, the required mobility of the ring was provided by the presence of an initial “soft” stage of shock absorber characteristics (see Chapter 6). However, the initial force of the springs should be sufficient to advance the ring into the initial position, considering friction in the seals and other resistances. All of the shock absorbers work only on compression, thus, for any movements, the ring approaches the docking frame. A great deal of energy is absorbed in the second stage of the stroke of the shock absorbers, and the force of the hydraulic dampers and their springs are significantly larger than the initial stroke. The force of the springs in the second stage should be sufficient to maintain the ring in the equalized position in the final portion of coupling as the guide rods enter the sockets. Coupling is done by one electrical drive with three cables wound around one drum (Figure 1.29). For uniform retraction to the frame the cables are attached to the ring through a set of springs which compensate for the different lengths and rigidities of the cables, and for their extension during use. The accuracy of the position of the ring in its
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