Introduction
The reverse dial indicator method of alignment is probably the most popular method of measurement because the dial indicators are installed to measure the relative position of two shaft centerlines. This presentation will emphasize this method because of the ease of graphically illustrating the shaft's position.
What is Reverse Alignment?
Reverse Alignment is the measurement of the axis or the centerline of one shaft to the relative position of the axis of an opposing shaft centerline. This measurement can be projected the full length of both shafts for proper positioning if you need to allow for thermal movement. The measurement also shows the position of the shaft centerlines at the coupling flex planes, for the purpose of selecting an allowable tolerance. The centerline measurements are taken in both horizontal and vertical planes.
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Learning How to Graph Plot
Graphical alignment is a technique that shows the relative position of the two shaft centerlines on a piece of square grid graph paper.
First, we must view the equipment to be aligned in the same manner that appears on the graph plot. In this example, we view the equipment with the "FIXED" on the left and the "MOVEABLE" on the right. This will remain the same view both vertically and horizontally.
Measure:
A. Distance between indicators
B. Distance between the indicator and the front foot
C. Distance between feet
= 10"
= 5"
=11"
To eliminate confusion the plus and minus signs
should be marked on the graph.
Graph paper layout