The KD4 Coupling is designed for medium and heavy duty applications. It only requires angular misalignment capacity as in the case of a three bearing installation of floating shaft arrangements. For complete floating shaft assemblies, consider a KD41. A KD41 uses two single KD4 flex halves in conjunction with a solid center shaft. KD42 designed as a drop-in replacement to gear coupling floating shafts. For lighter weight or higher stiffness, a tubular floating shaft is available.
With floating shafting for gear couplings, an unsupported floating shaft is used to span the gap between the driving and driven shafts. This is when the shafts are widely separated. The two couplings required at each end of that shaft consist of one half of a standard coupling bolted to a rigid hub. Each unit is called a Flex-Rigid Coupling. Usually the rigid hubs are mounted on the driving and driven shafts. This is so that the flex halves on the floating shaft may be replaced without disturbing the connected equipment.