Selecting a coupling for a precision drive system requires more than comparing torque ratings and shaft diameters. The way torque is transmitted, the acceptable alignment limits, operating environment and maintenance expectations all influence the decision. A disc coupling and a magnetic coupling can both be used in specialised drive systems, but their operating principles are fundamentally different. Understanding these differences helps engineers avoid applying one design where the other would be more appropriate. How a Disc Coupling Transmits Torque A disc coupling mechanically connects two shafts through flexible metallic disc packs. The discs transmit torque while flexing to accommodate specified amounts of angular, parallel or axial misalignment. Because the flexible elements are metallic, disc couplings do not depend on elastomeric inserts. They are often considered for high-speed or precision applications that require torsional stiffness and low-backlash operation. However, th...