Flexible couplings

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.