A signal to shut off the drive comes from the docking compatibility sensors. For the drive to couple the frames with maximum force, the drive is turned on several seconds after the sensor fires. The rod is held in a coupled position by the stopper coupling, and by a braking reducer after the electrical engines are switched off. Standard undocking occurs is done with the docking mechanism drive. To prepare for undocking the rod is moved out to the extreme forward position. Using average thrust and a clamp brace, a small screw is initially held immobile; the springs of the shock absorbers are compressed, storing energy for subsequent separation of the spacecraft. Tn the extreme forward position the clamp triggers, the screw is released, and the head moves forward due to the action of the springs. The latches of the head are recessed by the internal thrust. Due to the energy of the springs and additional action of the jet control system of the active spacecraft, the spacecraft separate. Rack-up undocking may be done by the active or the passive spacecraft. On command for back-up undocking, the active docking assembly fires the docking mechanism. On the passive docking assembly the pyrotechnic bolts are fired, releasing the latches of the socket. The docking mechanism (Figure 1.8) is functionally and structurally the most complex part of the active docking assembly. The rod of the docking mechanism is installed on guides, which consist of four cruciform bearings in grooves of the tail part of the hull. The rod is in the form of a screw with a bearing-screw converter. This converter has a number of unique properties, including the ability to convert the rotational motion of the nut in the gradual shifting of the screw. This property made it possible to use the same type of converter in the longitudinal shock absorber; a gear on the nut of the small screw converter is the rod of the shock absorber, which is linked with the rods on the output shafts of the electromechanical brake. These elements are used in all subsequent modifications of the electromechanical type docking device. Control of the docking of the Soyuz spacecraft (Figure 1.9) is possible for manned and unmanned flights. Standard docking is done automatically, as a direct continuation of the approach process. This transition occurs on a signal from contact sensor 1. If in 10 seconds the linkage sensor does not fire, then the
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