SHAFT COUPLINGS

Couplings are used to connect the shaft of a driver,such as a turbine or a motor,to the shaft of a driven machine,such as a pump or generator.There are basically two types of couplings;rigid and flexible.
Rigid couplings require precise alignment and most commonly are used in vertical units where the entire weight is supported by thrust bearings in the motor or generator.Flanged couplings are used on large,vertical units and consist of precisely machined flanges on each shaft connected by a series of coupling bolts around the perimeter of the flanges.
Flexible couplings are designed to accommodate slight misalignment between shafts and to some extent,dampen vibration.If properly aligned,most couplings should require very little maintenance outside of periodic inspection and in some cases lubrication.Over time,the alignment between the pump and its driver can deteriorate,increasing stress on the coupling which can lead to a shorter life.