More important than ever: Page 4

Due to the high performance density, four new-generation EAS-element clutches are integrated into a rolling mill between the output shafts of the pinion stand gearbox and the cardan shafts which combine the gear with the roll stand. The four shafts lie so close together that it would be impossible to accommodate standard torque limiting clutches due to the large outer diameter.

During the development of torque limiting clutches, the increase in performance density and speed will continue be one of the most important features in the system specifications. Manufacturers who have subjected their clutches to comprehensive long-term trials and who are able to look back on decades of field experience know-how know the performance and strength limits of their products precisely. They are in a position to permit higher torques than those defined today without having to reduce safety. Torque, speed and lifetime are parameters which influence each other. If, for example, the user only demands a short lifetime, because overload cases occur only occasionally, the manufacturer can, after discussion and inspection of all influence variables,
specify a higher permitted torque than that stated in the catalogue. A prerequisite for this, of course, is that all the components involved are capable of withstanding the higher load. In the same way, a higher torque can also be permitted at reduced speeds; in some circumstances even without a reduction in lifetime.

Servomotor suppliers imply that servomotors with power control offer cost-effective protection against overload, thus making torque limiting clutches unnecessary. In fact, this is only the case in a few exceptions. In practice, power regulation can only be seen as a practicable alternative for applications with low dynamics and soft collisions.

This situation will in future continue to develop in favour of mechanical torque limiting clutches due to the technical developments in mechanical engineering. Production speeds are increasing constantly. In addition, higher precision is required. This can only be achieved with extremely rigid machine constructions. High speeds and rigidity, however, lead to hard collisions during system malfunctions. In such cases, only torque limiting clutches with instant separation are able to prevent a large amount of subsequent damage.