vibrate noticeably and will cause a chattering noise.
HAND TOOLS
Larger armatures, which do not fit in an external
The hand tools used in rewinding armatures are
growler, may be checked by moving an internal growler
relatively few and simple. In fact, they are usually
over the outside surface of the armature. Internal
handmade by Electrician's Mates engaged in this work.
growlers are used primarily to check stator windings,
Figure 7-44 shows the following tools:
which will be covered later in this chapter under
three-phase stator repair.
1. A fiber from, which is used for shaping the coil
ends after the coils are placed in the slots
You should use a dial indicator for armature com-
mutator radius checks (fig. 7-43). Ensure commutators
2. A steel slot drift, or tamping tool, which is used
are not out-of-round more than 1 mil (0.001 inch).
for driving the coils to the bottom of partly
closed slots
REWINDING PROCEDURES
3. A lead lifter, which is used for lifting the coil
leads from the commutator risers
When tests or observations show that a piece of
rotating electrical machinery needs replacing and no
4. A hacksaw blade, which is used for removing
replacement is available, rewinding is necessary. The
the fiber wedges that hold the coils in the slots
process for rewinding a piece of rotating electrical gear
5. A handsaw, which is used for undercutting the
is basically the same for all types of machines. The
commutator mica between the segments
process can be divided into 9 key steps:
6. A wedge driver, which is used for driving the
1. Disassembly
fiber wedges out of the slots
2. Burning/stripping
7. A lead drift, which is used for cutting off the
3. Recording data
leads at the risers
4. Cleaning
8. A rotation indicator, which is used as an aid to
determine the proper connections of the
5. Insulating
windings
6. Winding
9. A wire scraper, which is used for removing the
7. Electrical testing
insulation from the ends of the coil leads
8. Varnishing
10. A wedge inserter, which is used for driving the
wedges into partly closed slots
9. Assembly
Figure 7-43.--Measuring commutator out-of-round with a
dial indicator.
Figure 7-44.--Armature rewinding hand tools.
7-30
