Page 72 - Machinery Component Maintenance

Maintenance Organization und Control for Multi-Plant Corporations 57

turer. Factory field servicemen lead a rough life: 16-20 hour or more
shifts are common, as well as frequently being away from home. Attri-
tion is high. You will find some very good and some very bad ones. Keep
a list of those to invite back, as well as those you would rather not use
again.

The Overhaul

During the course of the overhaul, it is very important to keep track of
the job on an hour-to-hour, shift-to-shift basis. Companies using a shift
log or diary for this purpose have found it to be an invaluable communi-
cations tool. The critical dimension diagram and the alignment diagram
should likewise be kept available for ready reference, as should the turn-
around book or T/A package mentioned earlier.
The use of a good quality camera and a capable photographer to docu-
ment details of the overhaul is strongly recommended. A good T/A pack-
age will include a pictorial sequence of assembly and disassembly steps,
as we will show later. After all, if you do a good job, it will be three to
five years or longer before anyone sees the inside of the machine again.
Consider using both a 60-second instant color picture and 35-mm single
lens reflex camera, and keep in mind the merits of video taping to pro-
vide training films for the maintenance department.
Before the actual shutdown of the machine is the time to take a final set
of hot alignment data, if such a program is currently in use at your plant.
There are, of course, several accepted methods for checking hot align-
ment. One is the use of eddy current probes, either inside the coupling
guard or on the machine cases. A second is the optical method using a
transit and targets on the machine train. A third is the use of a telescoping
measuring rod with reference points on each machine and benchmarks on
the foundation. A fourth method may involve laser optics.
If you don't currently check running hot alignment (as opposed to the
old method requiring a shutdown/alignment check, which has proven to
be both inaccurate and unreliable), we would strongly recommend evalu-
ating the various systems to see which one best fits your needs. As with
reverse dial indicator alignment, a good hot alignment method can be a
real money saver. Several items should be checked after the machine has
stopped turning, but before the actual disassembly begins:

1. The coupling: If it is a gear coupling, is it free to move on the gear
teeth'?
2. Look for broken coupling bolts. Broken bolts can indicate several
problems, the most likely being incorrect bolt torque on installa-
tion, the wrong bolt material, or mismachined coupling flanges.