The design feature of these discs is an increase in the contact surface of the springs with the stop disc. The specific pressure of the support coils of the springs on the disk parts has been reduced.
Operation of these discs provides:
increase in the disc motor resource by 2 times without taking into account the change of friction linings;
protection of the surfaces of the flywheel and pressure plate from damage in the event of a breakage of the spring, which is a difference from the design with open springs;