Page 206 - Machinery Component Maintenance

188 Machinery Component Maintenance and Repair

Now install face and rim setup on the actual machine, and zero the
indicators. With indicators at the top, deflect bracket upward an amount
equal to the appropriate rim sag, reading on the rim indicator, and note
the face indicator reading. The face sag correction with indicators at bot-
tom would be this amount with opposite sign. If zeroing the setup at the
bottom, the face sag correction at the top would be this amount with same
sign (if originally determined at top, as described).

Face Sag Effect-Examples

Example 1

Face and rim indicators are to be used together as shown in Figure 5-3.
Assume you will obtain the following from your sag test:

Rim sag with rim indicator only = .004 in.
Rim sag with two indicators = .007 in.

Mount the setup on the machine in the field, and with indicators at top,
deflect the bracket upward .007 in. as measured on the rim indicator.
When this is done, the face indicator reads plus .002 in. Face sag correc-
tion at the bottom position would therefore be minus .002 in. If you wish
to zero at the bottom for alignment, but otherwise have data as noted, the
face sag correction at the top would be plus .002 in.

Example 2
Face and rim indicators are to be used separately to reduce sag. Both
indicators are the same type and weight. Other basic data are also the
same.
Install face indicator and temporary rim indicator on the machine in the
field, and place in top position. Zero indicators and deflect upward ,004
in. as measured on rim indicator. Face indicator reads plus .0013 in. Face
sag correction at the bottom would therefore be minus .0013 in, If zero-
ing at the bottom for alignment, but otherwise the same as above, face
sag correction at top would be plus .0013 in.

Example 3

This will determine sag for “3-Indicator Face-and-Rim Setup” shown
in Figure 5-4.
Set up the jig to the same geometry as for field installation but with rim
indicator only and roll 180” top to bottom on pipe to get total single indi-
cator rim sag - (Step 1).