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2.9 Alignment using a graph (Reverse Alignment)
A
B
CL
CL
F2
F1
FIGURE 1
NOTE
With reverse alignment there are certain points which must always be born in mind.
A)
The pump coupling hub is referred to as A. The motor coupling hub is referred to as B.
The motor is aligned to the pump which is considered to be the datum.
B)
The dial test indicator on hub A is secured to hub B and vice versa and both hubs are
rotated together to obtain readings. For vertical alignment the Dial Test Indicator's are
zeroed on the top and they are read at the bottom - 180 degrees.
For horizontal they are zeroed at the side away from the person doing the alignment and
called far in the text and read on the opposite side and called near in the text.
C)
To plot the graph the above measurements must be recorded, A to B, this is the distance
between the Dial Test Indicator pointers which should be positioned halfway along the hub.
A to F1, this is the distance to the first foot centre or to the centre of the holding down bolt
hole.
A to F2, distance to second foot centre.
D)
Acceptable tolerance for vertical and horizontal alignment is 0.05mm (0.002in). Total
indicator reading.
