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Vertical Drilling Motor, Type GE752, GEK–91584D
43
FIG. 25. COMMUTATOR TIGHTENING.
E–4270B.
WARNING: During resurfacing operations,
eye protection and a respirator should be
worn to protect personnel from dust and fly-
ing particles.
use slot guides and depth gauges for accurate, uniform
cuts. Make a few practice passes over a scrap commu-
tator to get the “feel” of the tool. Care must be taken to
prevent the power undercutter from jumping out of the
slot and across the commutator surface. The high–
speed operation of the blade will quickly gouge the com-
mutator.
1. After a commutator has been resurfaced, the
mica between the bars should be undercut to a
depth of 0.047 in. Undercutting should be done
with a sharp–edged tool with a cutting width of
0.063 in.
2. Blow loose material off the commutator with dry,
compressed air.
FIG. 26. COMMUTATOR PRESSING
DIAMETER. E–18140
WARNING: When using compressed air for
cleaning purposes, flying debris and particles
may present a hazard to personnel in the im-
mediate area. Personnel should be provided
with, and trained in the use of, personal pro-
tective equipment as specified by applicable
federal or state safety regulations.
Raking
Resurfacing usually leaves particles and slivers of
copper hanging on the bar edges or lodged in the under-
cut slots. These must be removed before the motor is
placed in service, or the particles may bridge the side
mica and cause a flashover.
1. Brush out dirt and copper whiskers attached to
the trailing edge of the bars with a stiff–bristle
brush; preferably one with nylon bristles. A new
paint brush or stencil brush with the bristles cut
short for added stiffness may also be satisfacto-
ry. If stoning and undercutting have produced
considerable dragging of copper from the edges
of the bars, use a raking tool to remove the cop-
per fins and ragged edges. Use the tool to rake
the bar edges with the point inserted in the slot so
that sides of the V rake the trailing edge of the
bar. If the tool is ground with flat sides and used
with moderate pressure as a raking tool, it will re-
move ragged copper fins and break the sharp
1
5
9
3
7
11
2
10
4
8
6
12
FIG. 27. COMMUTATOR BOLT TIGHTENING
SEQUENCE. E–4502.