6.3. Friction Self-Adjusting Brake In the majority of electromechanical docking devices the main energy absorbing element of the longitudinal shock absorber is the friction brake (see, for example, [20]). This is due not only to its good correspondence to the combined shock absorption-drive scheme, but also due to its high specific characteristics (w , full absorption of energy without “recoil”). Moreover, the brake can absorb most of the “recoil” energy (for example, due to the elasticity of the construction) on the reverse course of the shock absorber. The ball force regulator, which compresses the package of disks (see Figure 6.5) provides stable momentum of the friction (with an accuracy of of the nominal value in the range of temperatures . Due to the different inclination of the channel of the ball regulator it is easy to attain different value of the momentum of the brake during rotation in one direction (in shock absorption) or the other (in retraction). The brake has a substantial energy capacity: in absorbing 1 kJ of energy its disk is heated by only 20*. The mass of the rotating parts of the brake applied to the motion of the rod of the docking mechanism is equal to where is the moment of inertia of the moving parts of the brake; is the transmission ratio of the reducer; s is the pitch of the screw. The momentum of the brake is proportional to the number of disks n for a given specific pressure between them and moment of inertia , also virtually proportional to . Thus, to reduce the size and to reduce the inertia of the brake one should increase the specific pressure to a maximum acceptable value (for the baked material disks used in the brake . To reduce one can increase the number of disks n, increase the momentum of the brake, and decrease the transmission ratio . However, increasing the number of disks worsens the work of the package; experience shows that it is reasonable to have a package of 20
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