Some mechanical seals are designed to very fine tolerance. Some of the damages to mechanical seals and bearings can sometimes be a result of misalignment of pump shaft with the motor shaft. Whenever these machineries are dismantled or probably the machine is not working as expected, prop shaft alignment is required.
One of the reasons for prop shaft alignment is to ensure that the center line of the motor rotor shaft coincides exactly with the centerline of the driven machinery. In essence, if you want smooth running of your machinery then you should consider prop shaft alignment. Alignment plays a vital role in ensuring that the machine works in a perfect and efficient manner with minimum vibration.
So long as both shafts are not crooked, the two alignments that need to be checked for any adjustment include angular alignment and offset alignment.
To check whether or not the shafts have any angular displacement between them you need to insert a feeler gauge between coupling faces and rotate both coupling halves at the same time. The feeler gauge readings are checked at four points on the shaft coupling. In order to correct the misalignment, shift the machinery.
One of the tools used in checking the radial alignment is a straight edge ruler. First, place the ruler across the coupling halves at the top, bottom and both sides any gaps between both coupling halves will indicate the shaft is offset slightly. In order to correct the misalignment, you can either shift the motor or put shims to lift the motor or machinery itself.
Make sure you bolt tightly the motor and driven machine to the base once the alignment position of the machinery has been completed. Shaft alignment is a prerequisite to running machines, the misalignment of which can cause malfunctions, accidents and injuries. Prop shaft alignment can be a real pain in both time and money aspects. Some people think of prop shaft alignment as rocket science. However, correcting misalignment is simple and easy only if you consult a professional.