difficulties. Moreover, the weight of the construction increases and additional potential failures appear that are linked with the need to open and close the hatches. At present the joint is carefully protected in all stages of preparation for flight; in the final operations before the launch of the rocket booster the protective hatches are removed, and final checking and cleaning of the joint are done, including careful cleaning of the rocket booster cowl. One of the ways which may be used to solve this problem is the use of APDA seals with both contact of resin with resin and resin with metal. For example, on long-term orbital stations, which are subjected to long periods in open space, the docking assemblies are installed without joint seals, and hermeticity is provided by a seal on the joint of the transport ship. Tf two craft must be docked, the seal is provided by the contact of resin with resin. 3.7. Lubricant Materials in Docking Devices The following types of lubricants are used on the many rubbing elements of the docking device: 1) plastic lubricants; 2) liquid oils; 3) solid anti-friction coatings based on molybdenium disulfide (see, for example, [24]). The majority of the bearings, gears, and other moving parts of the mechanisms, including the hermetic ones, are lubricated with synthetic plastic lubricants based on silicon-organic compounds. These materials have a low evaporation rate in vacuum, and provide good protection against atmospheric corrosion. The temperature of congealing is —60*C to —70*C.; however, in minus temperatures their viscosity is substantial, and the break-away torque of the units is increased. Even with measured service the friction increases several times compared with the normal temperature. This increase is acceptable in the start-up of DC drives, including small power electrical engines which have a large momentum ratio /Wn/Afw. However, in elements of the differential connections of peripheral docking devices this increase in friction is unacceptable. Thus, to lubricate the bearings in differential blocks and elements which connect the rods of the APDAs liquid silicon-organic oil is used. A thin layer of this oil does not provide sufficient protective anti-corrosive properties. This required the use in the APDAs of bearings made of corrosion-resistant steels. A11 the gears, as before, are
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