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Installation
Alternate method of alignment
An approved method for putting the coupling halves in final accurate alignment is by the use of
a dial indicator. Check alignment by straight edge, taper gauge or feelers as accurately as
possible by the procedure indicated above.
Bolt the indicator to the pump half of the coupling, with the indicator button resting on the other
half coupling periphery, set the dial to zero, and chalk mark the coupling half at the point where
the button rests. For any check, top, bottom, or sides, rotate both shafts by the same amount;
i.e., all readings on the dial must be made with button on the chalk mark.
The readings will indicate whether the driver has to be raised or lowered or moved to either
side. After each movement, check to see that coupling faces remain parallel to one another.
With this method, accurate alignment of shaft centers can be obtained even where faces or
outside diameters of the coupling halves are not square or concentric with the bores, provided
all measurements for angular alignment are made between the same two points on the faces,
and all measurements for parallel alignment are made between the same two points on the
outside diameters. Gross deviations in squareness or concentricity, however, may cause
problems due to coupling unbalance or abnormal coupling wear and may need to be corrected
for reasons other than accomplishment of shaft alignment.
Alignment of gear type couplings
Gear type couplings are aligned in the same manner as outlined above. However, the coupling
covers must be moved back out of the way and measurements made on the coupling hubs as
shown Gear coupling alignment.
Figure 8: Gear coupling alignment
Factors that may disturb alignment
The unit should be checked periodically for alignment. If the unit does not stay in line after
being properly installed, the following are possible causes:
• Settling, seasoning or spring of the foundation.
• Wear of the bearings.
• Pipe strains distorting or shifting the machine.
• Springing of the baseplate by heat from an adjacent steam pipe or from a steam turbine.
• Shifting of the building structure due to variable loading or other causes.
• Loose nuts or bolts on the pump or driver assembly.
10
Model JC Installation, Operation and Maintenance Instructions
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