When transmitting torque from a drive shaft to a driven shaft, flexible couplings:
- absorb and dampen irregularities in the torque,
- distribute peak loads,
- allow misalignments and offsets between the shafts,
- permit some distortions in the mounting beds,
- avoid the unwelcome constraints that may occur if a rigid coupling were fitted in the same conditions,
- allow a lighter construction, with wider tolerances, and lower cost. In particular, a flexible coupling is absolutely essential if the machines that are coupled are on flexible mountings. Moreover, there is no play in a flexible coupling, and it therefore runs silently, without friction and does not need to be greased.