Page 238 - Machinery Component Maintenance

220 Machinery Component Maintenance and Repair

(Text continued from page 21 6)
13. Look at drawing and decide whether north, south, east or west at
S, and mark 7th line of interpretation.
14. Ditto for A, and mark 9th line.
15. Get out plotting board and overlay.
16. Erase overlay.
17. Mark “up” arrow and directional arrow.
18. Move overlay horizontal red line to bottom border, with vertical
red line coinciding with right border.
19. Add up linear machine dimensions, and choose bottom horizontal
scale, A, B, C, or D.
20. Lay out and mark planes S and A, and IB and OB feet. May re-
quire two IB and OB marks if different positions for shim centers
and horizontal foot indicators. Use narrow marks.
21. Move overlay to horizontal zero-zero line, and mark coupling
measurement diameter above and below zero, using same scale as
used at bottom.
22. Move overlay to represent vertical IS condition. Read and record
required foot moves to get to zero-zero alignment. Also read and
record face gap difference.
23. Ditto for horizontal. The basic problem has now been solved, to
get the alignment to “zero-zero.” If thermal growth is not to be
considered, all of the “versus-desired” spaces may be filled with
zeros, and subsequent check interpreted data should be compared
to zero. If growth is to be considered, continue with step 24.
24. Refer to given desired offsets at feet, coupling faces, or rim mea-
surement planes. If any two offsets are given for vertical, the other
three can be solved. Likewise for horizontal. To do so, lay the
marked overlay into the desired offset position on the plotting
board, and read off the remaining quantities. For example, if foot
offsets are given, use these to position the overlay, and then read
off the corresponding offsets at coupling face and planes A and S.
If offsets are given in terms of desired face gap and centerline off-
set at plane A, position the overlay accordingly and read the values
at plane S and both feet. Care must be used to keep the overlay red
line intersection on the right-hand border of the grid.
25. Once the “versus-desired” values have been filled in, the next step
is to combine the foot offsets with the foot moves calculated for
zero-zero alignment, to get the net foot movements.
26. After making the moves and tightening hold-down bolts, a new set
of alignment readings should be taken and interpreted. These
check-interpreted values can then be compared to the desired val-
ues to see whether the alignment is within tolerance or if further
corrections must be made.